Howdy folks, my 2002 VFR800 ain't running up to normal temps.
She's currently just shy of 37,000mi and I've had the "pleasure" of replacing 2 thermostats for being stuck open.
The last time she stuck open was a few months ago, and since that replacement, "normal" temp has been about 166F. She will on occasion reach higher temps, for example last night at 90F air temp and running in stop/go traffic it was over 200F.
assuming the t-stat was stuck open again, in under 3k mi, or simply the wrong temp, I replaced it a couple weeks ago. Only to discover that the t-stat was NOT stuck open, the t-stat was marked the correct 82C. I went ahead and replaced it but I'm still having the same issue.
Fuel mileage is down to about 31-33mpg.
no mods have been done to the engine or exhaust.
I have verified that the on-board temp gauge is within a few deg F of actual. Close enough to trust it.
Which temp gauge did you verify? The air temp, or the coolant?
Is your fan stuck on / coming on early?
If the thermostat is functioning normally, the temp sensor is correct, and your fan is staying off until the 102C limit, and your bike is still running cold... What coolant are you using? There's not much else envolved... It's a pretty simple system...
[image: View Post]magicman, on May 13 2009, 11:48 AM, said:
Which temp gauge did you verify? The air temp, or the coolant?
Is your fan stuck on / coming on early?
If the thermostat is functioning normally, the temp sensor is correct, and your fan is staying off until the 102C limit, and your bike is still running cold... What coolant are you using? There's not much else envolved... It's a pretty simple system...
ECT sensor is the one I checked. Air temp is approx and I ain't worried about it.
The fan is not stuck on and wasn't on when it reached 200F yesterday so I'm assuming it is functioning correctly.
I replaced the coolant using automotive coolant that meets all the OEM required spec mixed 50/50 with distilled water. I suppose its possible this is the issue, but I can't figure out why a coolant that meets all the specs, wouldn't work. :blink:
Your fan won't kick on until 221 F. Then it turns off at 209 F. So if the hottest your bike got was 200 F then the fan wouldn't have turned on.
And some how I doubt it is your coolant based on what you have said.
[image: View Post]tx_vfr, on May 13 2009, 12:12 PM, said:
[image: View Post]magicman, on May 13 2009, 11:48 AM, said:
Which temp gauge did you verify? The air temp, or the coolant?
Is your fan stuck on / coming on early?
If the thermostat is functioning normally, the temp sensor is correct, and your fan is staying off until the 102C limit, and your bike is still running cold... What coolant are you using? There's not much else envolved... It's a pretty simple system...
ECT sensor is the one I checked. Air temp is approx and I ain't worried about it.
The fan is not stuck on and wasn't on when it reached 200F yesterday so I'm assuming it is functioning correctly.
I replaced the coolant using automotive coolant that meets all the OEM required spec mixed 50/50 with distilled water. I suppose its possible this is the issue, but I can't figure out why a coolant that meets all the specs, wouldn't work. :blink:
That's what I have been running for a year (knocks on head) and it has been running about right temps, 100F or so above ambient.
Are you running a PCII, III, etc?
Others, could bad o2 sensors cause this? Is running overly rich enough to keep it from getting completely up to temp?
I wonder if a lazy oxygen sensor is causing it to run rich and therefore cooler.That happens to some of the cars I work on and it doesn't turn on the check engine light.
Is it running a little sluggish or anything like that?
This is the second bike I 've heard of with the same symptoms.
Running at 166 F is the low end of normal and does not necessarily indicate a stuck thermostat. Mine ran at 140 F when air was at 40 F, that is stuck open. 31-33 mpg does indicate a problem though. I don't know what that would be. Something causing a rich mixture could be a possibility. There are a lot of hoses and wires to connect to the right place when getting to the thermostat. Did something get misplaced?
[image: View Post]vanion2, on May 13 2009, 12:20 PM, said:
Your fan won't kick on until 221 F. Then it turns off at 209 F. So if the hottest your bike got was 200 F then the fan wouldn't have turned on.
And some how I doubt it is your coolant based on what you have said.
Thats what I was thinking, so didn't worry about the fan.
[image: View Post]thereisnospoon, on May 13 2009, 12:26 PM, said:
[image: View Post]tx_vfr, on May 13 2009, 12:12 PM, said:
[image: View Post]magicman, on May 13 2009, 11:48 AM, said:
Which temp gauge did you verify? The air temp, or the coolant?
Is your fan stuck on / coming on early?
If the thermostat is functioning normally, the temp sensor is correct, and your fan is staying off until the 102C limit, and your bike is still running cold... What coolant are you using? There's not much else envolved... It's a pretty simple system...
ECT sensor is the one I checked. Air temp is approx and I ain't worried about it.
The fan is not stuck on and wasn't on when it reached 200F yesterday so I'm assuming it is functioning correctly.
I replaced the coolant using automotive coolant that meets all the OEM required spec mixed 50/50 with distilled water. I suppose its possible this is the issue, but I can't figure out why a coolant that meets all the specs, wouldn't work. :blink:
That's what I have been running for a year (knocks on head) and it has been running about right temps, 100F or so above ambient.
Are you running a PCII, III, etc?
Others, could bad o2 sensors cause this? Is running overly rich enough to keep it from getting completely up to temp?
I don't have an PC's on it. Other then disconnecting the flapper, and removing the snorkle, its 100% stock on the engine/drivetrain.
[image: View Post]ronimalvfr, on May 13 2009, 12:31 PM, said:
I wonder if a lazy oxygen sensor is causing it to run rich and therefore cooler.That happens to some of the cars I work on and it doesn't turn on the check engine light.
Is it running a little sluggish or anything like that?
This is the second bike I 've heard of with the same symptoms.
Haven't noticed it running any better or worse then it ever has. I don't ride it very hard.
[image: View Post]Bad Boy, on May 13 2009, 01:38 PM, said:
Running at 166 F is the low end of normal and does not necessarily indicate a stuck thermostat. Mine ran at 140 F when air was at 40 F, that is stuck open. 31-33 mpg does indicate a problem though. I don't know what that would be. Something causing a rich mixture could be a possibility. There are a lot of hoses and wires to connect to the right place when getting to the thermostat. Did something get misplaced?
I pulled out the Service Manual this morning and I'm almost proof positive that I have all the hoses connected correctly. As many hoses as there are, its gonna be hard to swap them around. Electrically, I know its connected correctly.
[image: View Post]tx_vfr, on May 13 2009, 01:12 PM, said:
I replaced the coolant using automotive coolant that meets all the OEM required spec mixed 50/50 with distilled water. I suppose its possible this is the issue, but I can't figure out why a coolant that meets all the specs, wouldn't work. :blink:
The problem doesn't seem to be it not working, but working too well.
Maybe you discovered the Uber coolant. :fing02:
My money is on the overrichness if the whole cooling system is in check.
I know this may sound like a contradiction but I would recommend doing the O2 sensor mod to see if this changes your symptoms or if they remain the same. This will eliminate the O2 sensors as being defective if your symptoms stay the same. If they change it is simple to pull the 330 Ohm resistors, reconnect your harness and consider replacing the O2 sensors or leave them in place for a "cheap" fix.
[image: View Post]vanion2, on May 14 2009, 08:25 AM, said:
I know this may sound like a contradiction but I would recommend doing the O2 sensor mod to see if this changes your symptoms or if they remain the same. This will eliminate the O2 sensors as being defective if your symptoms stay the same. If they change it is simple to pull the 330 Ohm resistors, reconnect your harness and consider replacing the O2 sensors or leave them in place for a "cheap" fix.
Just a thought.
As I understand the O2 system, removing them is going to make the ECU run rich. Which, I suspect, is already the problem I'm having. So I'm not sure how this is going to help :+1:
[image: View Post]ronimalvfr, on May 13 2009, 12:31 PM, said:
I wonder if a lazy oxygen sensor is causing it to run rich and therefore cooler.That happens to some of the cars I work on and it doesn't turn on the check engine light.
Is it running a little sluggish or anything like that?
This is the second bike I 've heard of with the same symptoms.
Unless mine is the second bike, make that 3 bikes you have heard of. I have much the same symptoms...only gets to 220 if I sit in traffic, normally runs 200 or less, and I get 30 mpg almost consistently. How can you test the O2 sensor?
[image: View Post]tx_vfr, on May 14 2009, 08:28 AM, said:
[image: View Post]vanion2, on May 14 2009, 08:25 AM, said:
I know this may sound like a contradiction but I would recommend doing the O2 sensor mod to see if this changes your symptoms or if they remain the same. This will eliminate the O2 sensors as being defective if your symptoms stay the same. If they change it is simple to pull the 330 Ohm resistors, reconnect your harness and consider replacing the O2 sensors or leave them in place for a "cheap" fix.
Just a thought.
As I understand the O2 system, removing them is going to make the ECU run rich. Which, I suspect, is already the problem I'm having. So I'm not sure how this is going to help :+1:
It's a simple test to verify if the problem are the O2 sensors. My bike came with the O2 mod and I don't have a PCIII but even running rich my bike still gets 38-42 mpg. If your O2 sensors are defective and causing you to run really rich the O2 mod may help you isolate the problem. Again, it's a cheap and easy way to check it out. Your bike so your call. I'm just giving some ideas I would try if it were my problem. :goofy:
[image: View Post]vanion2, on May 14 2009, 11:03 AM, said:
[image: View Post]tx_vfr, on May 14 2009, 08:28 AM, said:
[image: View Post]vanion2, on May 14 2009, 08:25 AM, said:
I know this may sound like a contradiction but I would recommend doing the O2 sensor mod to see if this changes your symptoms or if they remain the same. This will eliminate the O2 sensors as being defective if your symptoms stay the same. If they change it is simple to pull the 330 Ohm resistors, reconnect your harness and consider replacing the O2 sensors or leave them in place for a "cheap" fix.
Just a thought.
As I understand the O2 system, removing them is going to make the ECU run rich. Which, I suspect, is already the problem I'm having. So I'm not sure how this is going to help :+1:
It's a simple test to verify if the problem are the O2 sensors. My bike came with the O2 mod and I don't have a PCIII but even running rich my bike still gets 38-42 mpg. If your O2 sensors are defective and causing you to run really rich the O2 mod may help you isolate the problem. Again, it's a cheap and easy way to check it out. Your bike so your call. I'm just giving some ideas I would try if it were my problem. :beer:
Thanks for the extra explanation, just trying to understand how it was gonna work :goofy:
[image: View Post]vanion2, on May 14 2009, 11:03 AM, said:
[image: View Post]tx_vfr, on May 14 2009, 08:28 AM, said:
[image: View Post]vanion2, on May 14 2009, 08:25 AM, said:
I know this may sound like a contradiction but I would recommend doing the O2 sensor mod to see if this changes your symptoms or if they remain the same. This will eliminate the O2 sensors as being defective if your symptoms stay the same. If they change it is simple to pull the 330 Ohm resistors, reconnect your harness and consider replacing the O2 sensors or leave them in place for a "cheap" fix.
Just a thought.
As I understand the O2 system, removing them is going to make the ECU run rich. Which, I suspect, is already the problem I'm having. So I'm not sure how this is going to help :+1:
It's a simple test to verify if the problem are the O2 sensors. My bike came with the O2 mod and I don't have a PCIII but even running rich my bike still gets 38-42 mpg. If your O2 sensors are defective and causing you to run really rich the O2 mod may help you isolate the problem. Again, it's a cheap and easy way to check it out. Your bike so your call. I'm just giving some ideas I would try if it were my problem. :goofy:
I will give it a shot personally, as it's time to fill up so I can easily tell if the mileage changes.
First, I agree, doing a O2 sensor elim couldn't hurt. However, I doubt that is your problem. The ECU only looks at the O2 sensors at 4-5K when the throttle is steady. Any throttle movement should send it back to a open loop map. All the resistors do is cause the ECU to see a null when it is in that 4-5K range and wants to lean the mixture out further. When my thermostat went bad it would still open but would only close part of the way. It was similar to your condition. It would heat up in traffic but would tend to run cold on the open road. If its not your tstat or fan staying on, then I think you were on the right track with the ECT sensor. There are some troubleshooting checks in the fuel section where you can ohm it out. The other sensor would be the MAP sensor in the air box. If it�s bad it could affect your fuel mixture. Your air filter is clean right?
One last thought, your poor fuel mileage and the temp may not be 100% related to each other. If its cool out and I�m just cursing along mine runs right around 170F. I�ll see the temp go up to 180 and then go back down at the tstat opens. Now if you�re still running 166F when its 80 out something�s defiantly wrong. Good luck getting it figured out and post up if you find out the cause(s).
I installed another thermostat in the bike and its still running cold.
Sitting in the drive way, it works perfectly. But start driving down the road and within a mile, of <45mph, its down to the 167F that it seems to prefer.
I'm about 97% sure that I didn't, cause I can't, get the hoses mixed up on the thermostat housing.
Beyond that, I'm bumfuddled.
Nobody has mentioned the wax unit that controls warm-up. Could it be connected wrong or gone bad? You didn't say whether you bike was idling fast when warmed up.
I tried the O2 sensor mod, but removed it. I saw no change in mileage. I did notice on my trip to Colorado that my mileage was pretty good...I attribute my 33 MPG to city stop-n-go driving. Temps seem low, but why complain that it works to well? The answer to raising the temps might be to block the right side Rad with some cardboard...easy to remove if not needed.
[image: View Post]VFR-SPORT, on 29 October 2009 - 12:02 PM, said:
Nobody has mentioned the wax unit that controls warm-up. Could it be connected wrong or gone bad? You didn't say whether you bike was idling fast when warmed up.
Stan
Bike runs perfectly in all accounts except the low temp. Idle is spot on both cold and warm.
[image: View Post]Tightwad, on 29 October 2009 - 03:18 PM, said:
I tried the O2 sensor mod, but removed it. I saw no change in mileage. I did notice on my trip to Colorado that my mileage was pretty good...I attribute my 33 MPG to city stop-n-go driving. Temps seem low, but why complain that it works to well? The answer to raising the temps might be to block the right side Rad with some cardboard...easy to remove if not needed.
If this was how it was when I got the bike, I wouldn't think anything of it, but since I know its changed, I know it can do better. Normal mileage for her before she quite running warm enough was 40 around town and 44-48 highway.
[image: View Post]tx_vfr, on 30 October 2009 - 11:08 AM, said:
[image: View Post]VFR-SPORT, on 29 October 2009 - 12:02 PM, said:
Nobody has mentioned the wax unit that controls warm-up. Could it be connected wrong or gone bad? You didn't say whether you bike was idling fast when warmed up.
Stan
Bike runs perfectly in all accounts except the low temp. Idle is spot on both cold and warm.
[image: View Post]Tightwad, on 29 October 2009 - 03:18 PM, said:
I tried the O2 sensor mod, but removed it. I saw no change in mileage. I did notice on my trip to Colorado that my mileage was pretty good...I attribute my 33 MPG to city stop-n-go driving. Temps seem low, but why complain that it works to well? The answer to raising the temps might be to block the right side Rad with some cardboard...easy to remove if not needed.
If this was how it was when I got the bike, I wouldn't think anything of it, but since I know its changed, I know it can do better. Normal mileage for her before she quite running warm enough was 40 around town and 44-48 highway.
i am watching this thread closely. i am having similar probs... just did my t-stat, no change. i mileage seems to have dropped around 15%, and my temps won't get above
165 on the highway if it is any cooler than around 50deg f. when i am riding slower it stays down around 150-155deg.
i have experiemented with unplugging my pc, with no change. at idle or in traffic, it will run up to normal temps.
on a side note, you can change your t-stat without removing the throttle bodies. bit of a pita, but i figured i saved some time by just removing the injector rail and tps bracket.
A bad T-stat that causes any lower running temps will cause worse mileage most of the time because the ECU adds extra fuel when it see cooler engine temps.
BUT,
One factor that I haven't seen mentioned here yet that may or may not be an issue depending on where you live is "Winter Fuel Blends" or "Oxygenated Fuels"!
I know when I lived in Denver they brought out this crap called Oxygenated Fuel that was suppose to run cleaner, the problem was that it was about 20-30% less efficient than regular gas so my fuel mileage dropped and avg. of 25% on every vehicle I was forced to run it in.
Don't know if your State forces this crap on you, but it could be a factor if they do! :warranty:
[image: View Post]Baileyrock, on 30 October 2009 - 11:51 AM, said:
A bad T-stat that causes any lower running temps will cause worse mileage most of the time because the ECU adds extra fuel when it see cooler engine temps.
BUT,
One factor that I haven't seen mentioned here yet that may or may not be an issue depending on where you live is "Winter Fuel Blends" or "Oxygenated Fuels"!
I know when I lived in Denver they brought out this crap called Oxygenated Fuel that was suppose to run cleaner, the problem was that it was about 20-30% less efficient than regular gas so my fuel mileage dropped and avg. of 25% on every vehicle I was forced to run it in.
Don't know if your State forces this crap on you, but it could be a factor if they do! :warranty:
BR
excellent point, and one i haven't considered. i am going to look into this...
[image: View Post]Baileyrock, on 30 October 2009 - 11:51 AM, said:
A bad T-stat that causes any lower running temps will cause worse mileage most of the time because the ECU adds extra fuel when it see cooler engine temps.
BUT,
One factor that I haven't seen mentioned here yet that may or may not be an issue depending on where you live is "Winter Fuel Blends" or "Oxygenated Fuels"!
I know when I lived in Denver they brought out this crap called Oxygenated Fuel that was suppose to run cleaner, the problem was that it was about 20-30% less efficient than regular gas so my fuel mileage dropped and avg. of 25% on every vehicle I was forced to run it in.
Don't know if your State forces this crap on you, but it could be a factor if they do! :warranty:
BR
I live just a bit south of the DFW TX metroplex. I'm not sure if we get the winter mix fuel or not. I do know that this problem has been pretty consistent since summer '08 to present.
Any time the air temp is below ~90F and the bike is moving, she's not up to temp.
so i figured i would sync my starter valves because not only am i running cold, but it is fueling terribly, especially when i am rolling on the throttle.
so i can't get the #3 cyl. to match... vacuum is way low, and the valve is basically closed to get it the vacuum to match. at this point, it is a dead cylinder and the header is cold. so a vacuum leak.
the rubber vacuum hose from the body to the 5 way tee had a freaking crack in it! so i snip the end off, set my starter valves(the adjustments all make sense now...) and put it all back together.
bottom line:
mileage-33mpg to 40mpg
coolant temp at 40f ambient-140f to 160f
my plugs were pretty black, so yes, it was running rich(duh).
and yes,it took me a very long time to find the cracked hose. :biggrin: thank god i wasn't paying shop rate.
the hoses are pretty dried up, so maybe new hoses is my next project.
I just swapped the t-stat. again.
I took one of the t-stats I'd removed on a prior change, and tested it in a pot of water. Watching a candy thermometer, it opened at ~180F and was full open by 205F.
As an experiment, I put some JB weld on the weep hole beside the main valve. I know when I tried a t-stat from a ST1300, its extra weep hole, allowed too much water to pass through and not keep its temp up.
Started her up and ran her, and ... I don't believe it helped at all. I'll give her a proper test run tomorrow.
While I was in there, I triple checked all the hose routes, and they're all correct according to the FSM.
On the bright side, I can now do a full t-stat swap in under 2hrs. :fing02:
Thanks for the update tx_vfr. I've got a t-stat coming next week as I've got all the signs of a stuck t-stat but, as you are proving, there is potential for that not to be the problem.
My mpg is not horrible - last couple of tanks ~45mpg (that's not too far off from what I would expect from winter gas, its my first winter with the vfr) but if the temps are less than about 45F ambient it will never reach 150 degrees on my way to work.
[image: View Post]swimmer, on 27 November 2009 - 08:56 PM, said:
Thanks for the update tx_vfr. I've got a t-stat coming next week as I've got all the signs of a stuck t-stat but, as you are proving, there is potential for that not to be the problem.
My mpg is not horrible - last couple of tanks ~45mpg (that's not too far off from what I would expect from winter gas, its my first winter with the vfr) but if the temps are less than about 45F ambient it will never reach 150 degrees on my way to work.
Sounds like a stuck t-stat to me. Make sure you've got a long philips screw driver and you should be set. Its not all that complicated of a change.
I haven't checked the plugs in a few thousand miles. I checked them around 30k and they looked brand new. The PO put in high-dollar platinum plugs so they haven't needed replaced yet.
Took her for a 100mi spin yesterday and the temps hovered around 171F instead of 166F. Not that much in my mind, but it did seem to turn vastly better fuel mileage. I'll see how she does on the commute, which is quite a bit different then the ride I did yesterday and see how that goes.
I noticed that the left radiator was starting to feel quite warm when the bike was only running at 145F before I put the plastic back on. I thought that radiator wouldn't come into play till the t-stat opened.
I'm not sure what you blokes are all worried about. 167F = 76C = what the bike should run at on the open road in moderate or cold weather.
The engine will only ever get above 180F if the weather is warmer or if you're riding the tits off it. I did a track day at Phillip Island on the 1st of November on a 71 degree day, and even when wringing it's neck, my VTEC never went above 185F.
Now on hot days, she will easily sit at 228F in traffic, and never go below 194F even at speed.
I agree with kaldec. I live and ride all year long in south Alabama. My commute 1 way is 23 miles. When the weather is in the low 40's to high 30's the bike never reaches 150 operating temp due to the cold air keeping the engine below temps where the t-stat would open. There is only 1 problem associated with this....the V-tech will never come on for passing situations! you either have to hold the throttle open at stops to increase temps and dwaste gas...or let the bike warm up stationary prior to pulling out for your ride. CRASH
[image: View Post]CrasshYobo, on 29 November 2009 - 06:29 PM, said:
I agree with kaldec. I live and ride all year long in south Alabama. My commute 1 way is 23 miles. When the weather is in the low 40's to high 30's the bike never reaches 150 operating temp due to the cold air keeping the engine below temps where the t-stat would open. There is only 1 problem associated with this....the V-tech will never come on for passing situations! you either have to hold the throttle open at stops to increase temps and dwaste gas...or let the bike warm up stationary prior to pulling out for your ride. CRASH
I don't really understand what you are saying. If the t-stat is being kept closed that would allow the engine to heat up to "normal" operating temps. I think you've got your thinking backwards. By what you are saying, Honda made the motorcycle knowing that if you rode in temps around 40 degrees you would not have VTEC. Sounds to me like you have a stuck t-stat like I believe I have. I've got a new one coming next week so I'll not for sure then.
For those of that are pretty new to the VFR, will someone please chime in a verify that even at temps below 40 at steady speeds (no stop/go) the water temp should be above 150 degrees.
[image: View Post]swimmer, on 29 November 2009 - 06:57 PM, said:
[image: View Post]CrasshYobo, on 29 November 2009 - 06:29 PM, said:
I agree with kaldec. I live and ride all year long in south Alabama. My commute 1 way is 23 miles. When the weather is in the low 40's to high 30's the bike never reaches 150 operating temp due to the cold air keeping the engine below temps where the t-stat would open. There is only 1 problem associated with this....the V-tech will never come on for passing situations! you either have to hold the throttle open at stops to increase temps and dwaste gas...or let the bike warm up stationary prior to pulling out for your ride. CRASH
I don't really understand what you are saying. If the t-stat is being kept closed that would allow the engine to heat up to "normal" operating temps. I think you've got your thinking backwards. By what you are saying, Honda made the motorcycle knowing that if you rode in temps around 40 degrees you would not have VTEC. Sounds to me like you have a stuck t-stat like I believe I have. I've got a new one coming next week so I'll not for sure then.
For those of that are pretty new to the VFR, will someone please chime in a verify that even at temps below 40 at steady speeds (no stop/go) the water temp should be above 150 degrees.
yes 150 dgree should never be seen after bike is at full temp 1 mile after intitial temp read . even in sub freesing it should hold mid to high 160's worst case
[image: View Post]swimmer, on 29 November 2009 - 06:57 PM, said:
[image: View Post]CrasshYobo, on 29 November 2009 - 06:29 PM, said:
I agree with kaldec. I live and ride all year long in south Alabama. My commute 1 way is 23 miles. When the weather is in the low 40's to high 30's the bike never reaches 150 operating temp due to the cold air keeping the engine below temps where the t-stat would open. There is only 1 problem associated with this....the V-tech will never come on for passing situations! you either have to hold the throttle open at stops to increase temps and dwaste gas...or let the bike warm up stationary prior to pulling out for your ride. CRASH
I don't really understand what you are saying. If the t-stat is being kept closed that would allow the engine to heat up to "normal" operating temps. I think you've got your thinking backwards. By what you are saying, Honda made the motorcycle knowing that if you rode in temps around 40 degrees you would not have VTEC. Sounds to me like you have a stuck t-stat like I believe I have. I've got a new one coming next week so I'll not for sure then.
For those of that are pretty new to the VFR, will someone please chime in a verify that even at temps below 40 at steady speeds (no stop/go) the water temp should be above 150 degrees.
The point of a thermostat is to keep the engine in its ideal operating temp range.
When the engine reaches the t-stat's open point, and at the same time, ideal operating temp, the coolant circulates through the radiators to disipate any excess heat and keep the engine in that ideal range.
When the temp drops below that ideal range, the t-stat closes to keep the engine heat in the coolant.
I replaced the antifreeze in the bike over the holidays. I put in the Prestone gold antifreeze. the stuff that'll mix with any color anti-freeze. I mixed it 50/50 with distilled water.
Starting it up and running it at home, it didn't seem to help at all. Haven't had a chance to take the bike for a proper ride since I swapped it.
I didn't really expect this to solve anything, but it was a cheap check.
I rode for an hour on Saturday, temps in the 45 range, and the engine temp never got passed 165...most of the time it was around 150. Weather and cruising speed makes a big difference, because in the garage it heated up to 230 no problem.
Once this freezing Texas weather is gone do this (although this test works great in weather under 60 degrees - in the summer hot weather you probably would not even know you had a T-stat stuck open). Start the bike up and let it run for 15 minutes (setting). Then rev it up several times so the temp eventually gets above 190. Then go for a ride, one that gets up to speed out in the open. The wind going through the rads should bring the temp down gradually to somewhere between 165 and 175. This is when the T-stat should start closing to keep the temp in that range. If the temp drops below, say 165, you T-stat is sticking slightly open (it is not being allowed to close all the way). This will cause the bike to run rich and MPG will suffer.
[image: View Post]Tightwad, on 07 January 2010 - 04:57 PM, said:
I rode for an hour on Saturday, temps in the 45 range, and the engine temp never got passed 165...most of the time it was around 150. Weather and cruising speed makes a big difference, because in the garage it heated up to 230 no problem.
Sounds like your t-stat is stuck. Even in the 30's my never drops below 168. Which certainly wasn't the case before I replaced my t-stat a few weeks ago.
[image: View Post]ki-speed, on 07 January 2010 - 04:59 PM, said:
Once this freezing Texas weather is gone do this (although this test works great in weather under 60 degrees - in the summer hot weather you probably would not even know you had a T-stat stuck open). Start the bike up and let it run for 15 minutes (setting). Then rev it up several times so the temp eventually gets above 190. Then go for a ride, one that gets up to speed out in the open. The wind going through the rads should bring the temp down gradually to somewhere between 165 and 175. This is when the T-stat should start closing to keep the temp in that range. If the temp drops below, say 165, you T-stat is sticking slightly open (it is not being allowed to close all the way). This will cause the bike to run rich and MPG will suffer.
Good luck.
ki-speed (Mark)
This is correct , should really hold right at 170 minimum, no matter how cold the temp , 150 is way low
Corrosion is the problem with these thermos , just slightly seems to be all it takes. Too many model years have the issue, for this to be a bad batch.
I say Hondas own coolant , I've never had the trouble, but I dumped the Honda stuff when bike was new.
[image: View Post]ki-speed, on 07 January 2010 - 04:59 PM, said:
Once this freezing Texas weather is gone do this (although this test works great in weather under 60 degrees - in the summer hot weather you probably would not even know you had a T-stat stuck open). Start the bike up and let it run for 15 minutes (setting). Then rev it up several times so the temp eventually gets above 190. Then go for a ride, one that gets up to speed out in the open. The wind going through the rads should bring the temp down gradually to somewhere between 165 and 175. This is when the T-stat should start closing to keep the temp in that range. If the temp drops below, say 165, you T-stat is sticking slightly open (it is not being allowed to close all the way). This will cause the bike to run rich and MPG will suffer.
Good luck.
ki-speed (Mark)
The thermostat specs are begin open ~185F and full open by 210F. Inversely, the t-stat should be closed again at 185F. I'll give it a few degrees of cooling with the air moving over the engine, but it should not be down in the 160s.
Before this all began, even in low 40's for air temps, the bike ran at an even 180F when cruising down the road.
I started and ran the bike last night. Air temp about 50F. No wind, and no movement of the bike. She was sitting on the center stand in the driveway.
Within 8-10min engine temp was 160F. At one point, the temp climbed to 170 then almost instantly dropped back into the mid 160s.
This behavior continued for the full 20min I had it running.
[image: View Post]Jlewis50, on 08 January 2010 - 06:08 PM, said:
I was reading this thread and maybe you just have a bad temp sensor. Change the thermostat also.
I've checked the temp sensor and it is reading correctly.
Thermostat has been changed. 6x at this point.
[image: View Post]CrasshYobo, on 29 November 2009 - 06:29 PM, said:
I agree with kaldec. I live and ride all year long in south Alabama. My commute 1 way is 23 miles. When the weather is in the low 40's to high 30's the bike never reaches 150 operating temp due to the cold air keeping the engine below temps where the t-stat would open. There is only 1 problem associated with this....the V-tech will never come on for passing situations! you either have to hold the throttle open at stops to increase temps and dwaste gas...or let the bike warm up stationary prior to pulling out for your ride. CRASH
you have a stuck open thermostat , once the bike is at 170 it should not drop below no matter how cold it gets even 0 degrees, thats the job of the thermo not to allow that.
The problem you are stuck open and its simply not working at all
[image: View Post]spud786, on 13 January 2010 - 07:32 PM, said:
[image: View Post]CrasshYobo, on 29 November 2009 - 06:29 PM, said:
I agree with kaldec. I live and ride all year long in south Alabama. My commute 1 way is 23 miles. When the weather is in the low 40's to high 30's the bike never reaches 150 operating temp due to the cold air keeping the engine below temps where the t-stat would open. There is only 1 problem associated with this....the V-tech will never come on for passing situations! you either have to hold the throttle open at stops to increase temps and dwaste gas...or let the bike warm up stationary prior to pulling out for your ride. CRASH
you have a stuck open thermostat , once the bike is at 170 it should not drop below no matter how cold it gets even 0 degrees, thats the job of the thermo not to allow that.
The problem you are stuck open and its simply not working at all
the t-stat that is in it is not sticking open.
I put that t-stat in a couple months ago, with the same symptoms as before, pulled it out and inspected it, verified that its not stuck open and is opening at correct temps, and put it back in.
[image: View Post]tx_vfr, on 13 January 2010 - 09:07 PM, said:
[image: View Post]spud786, on 13 January 2010 - 07:32 PM, said:
[image: View Post]CrasshYobo, on 29 November 2009 - 06:29 PM, said:
I agree with kaldec. I live and ride all year long in south Alabama. My commute 1 way is 23 miles. When the weather is in the low 40's to high 30's the bike never reaches 150 operating temp due to the cold air keeping the engine below temps where the t-stat would open. There is only 1 problem associated with this....the V-tech will never come on for passing situations! you either have to hold the throttle open at stops to increase temps and dwaste gas...or let the bike warm up stationary prior to pulling out for your ride. CRASH
you have a stuck open thermostat , once the bike is at 170 it should not drop below no matter how cold it gets even 0 degrees, thats the job of the thermo not to allow that.
The problem you are stuck open and its simply not working at all
the t-stat that is in it is not sticking open.
I put that t-stat in a couple months ago, with the same symptoms as before, pulled it out and inspected it, verified that its not stuck open and is opening at correct temps, and put it back in.
I dont know, even mid 20's , I'm 170 degree within 2 mile of leaving the house like clockwork (at 95 degree first read), and never drops back below. Normally hovers between 170 to 180 in that weather.
Im completely stock, have you decatted or anything?
The cat needs heat to work, vtech shut off is 149 degree.
tx, I wonder if you've got a problem on the gauge itself. Not the sensor but the display. Its possible that if the gauge is getting low supply voltages or something it may not be reading correctly. If the sensor reads like a standard thermocouple (and without looking at it closer I am not sure) the meter/display will have some sort of source voltage as well as a signal voltage. Something wrong with one of these could cause a low or non-linear reading.
I don't have time to look through the wiring schematics right now but if there was a way to check that out it might be worthwhile. Just for my curiosity I'll try to take a look a the schematics tomorrow.
If you have a thermocouple perhaps you could run the motorcycle with the radiator cap off and compare water temps?
[image: View Post]spud786, on 13 January 2010 - 09:15 PM, said:
[image: View Post]tx_vfr, on 13 January 2010 - 09:07 PM, said:
[image: View Post]spud786, on 13 January 2010 - 07:32 PM, said:
[image: View Post]CrasshYobo, on 29 November 2009 - 06:29 PM, said:
I agree with kaldec. I live and ride all year long in south Alabama. My commute 1 way is 23 miles. When the weather is in the low 40's to high 30's the bike never reaches 150 operating temp due to the cold air keeping the engine below temps where the t-stat would open. There is only 1 problem associated with this....the V-tech will never come on for passing situations! you either have to hold the throttle open at stops to increase temps and dwaste gas...or let the bike warm up stationary prior to pulling out for your ride. CRASH
you have a stuck open thermostat , once the bike is at 170 it should not drop below no matter how cold it gets even 0 degrees, thats the job of the thermo not to allow that.
The problem you are stuck open and its simply not working at all
the t-stat that is in it is not sticking open.
I put that t-stat in a couple months ago, with the same symptoms as before, pulled it out and inspected it, verified that its not stuck open and is opening at correct temps, and put it back in.
I dont know, even mid 20's , I'm 170 degree within 2 mile of leaving the house like clockwork (at 95 degree first read), and never drops back below. Normally hovers between 170 to 180 in that weather.
Im completely stock, have you decatted or anything?
The cat needs heat to work, vtech shut off is 149 degree.
I'm sure its not meant to run that cold
The drive train is stock. No O2-elims, no pipes, no de-catting, nothing.
I would 100% agree with you except this problem has been happening over the span of 5 different t-stats.
[image: View Post]swimmer, on 13 January 2010 - 09:27 PM, said:
tx, I wonder if you've got a problem on the gauge itself. Not the sensor but the display. Its possible that if the gauge is getting low supply voltages or something it may not be reading correctly. If the sensor reads like a standard thermocouple (and without looking at it closer I am not sure) the meter/display will have some sort of source voltage as well as a signal voltage. Something wrong with one of these could cause a low or non-linear reading.
I don't have time to look through the wiring schematics right now but if there was a way to check that out it might be worthwhile. Just for my curiosity I'll try to take a look a the schematics tomorrow.
If you have a thermocouple perhaps you could run the motorcycle with the radiator cap off and compare water temps?
I checked the temp of the tanks on the radiators, using a IR/LASER temp gauge, and that temp was 2*F warmer then what the gauge was reading.
have you tried syncing your starter valves? it might point to other causes. it seems at low throttle opening is where you are experiencing cool conditions and poor mileage. i had the same issues and it was vacuum related.
[image: View Post]dirtbag, on 27 January 2010 - 10:14 AM, said:
have you tried syncing your starter valves? it might point to other causes. it seems at low throttle opening is where you are experiencing cool conditions and poor mileage. i had the same issues and it was vacuum related.
is there any drivability issues?
good luck.
I sync'd starter valves when I did the valve check at ~20k mi. Haven't messed with them since. You have point. I'll see about checking that.
Its not really at low throttle or at high throttle, just over all. I just put 300mi on the bike, mostly highway, running an indicated 90mph and the warmest it ever got was 172F
Nope, she runs like a top. No noticeable power decrease, no rough running, nothing.
[image: View Post]tx_vfr, on 29 November 2009 - 02:35 PM, said:
I noticed that the left radiator was starting to feel quite warm when the bike was only running at 145F before I put the plastic back on. I thought that radiator wouldn't come into play till the t-stat opened.
If your left radiator is getting hot before the thermostat is supposed to open then something is letting coolant flow through the system before its supposed to. If you've replaced the thermostat 6 times could you have hooked the coolant lines up wrong? You should be able to start at the radiator(s) and work your way backwards to see where your flow is coming from.
I've gone over the routes for the hoses multiple times and I'm 99% sure that the hoses are correctly connected. Most of the hoses simply can't be crossed up.
The route diagram in the FSM is rather small and very hard to read.
[image: View Post]tx_vfr, on 27 January 2010 - 05:18 PM, said:
I've gone over the routes for the hoses multiple times and I'm 99% sure that the hoses are correctly connected. Most of the hoses simply can't be crossed up.
The route diagram in the FSM is rather small and very hard to read.
Any updates on this? I'm curious to find out of the issue has been resolved.
Hey Tx_vfr I just read through this whole topic and your first post fits my symptoms exactly. The bike runs great, no power loss, smooth as can be, but the terrible fuel mileage (30-33) and low operating temps (167 about or less), ambient temps here 38-58 degrees lately. 27,000 mi on a 2004 with only an exhaust mod by previous owner.
As a note, I just bought this bike not long ago and had the shop replace all fluids, so my coolant is fresh and he said the plugs looked "brand new". I would think with us getting the poor fuel mileage, if it was due to running rich all the time, then the plugs would be fouled?
Have you made any progress at all? I admire your persistence and documentation of your problem. I wonder if we need a thermostat that is designed to open at a higher temp? Are there any available that fit?
Hey y'all, unfortunatly I haven't made any useful headway. I took the bike apart a bit over a week ago and pulled the t-stat housing out of the bike to inspect. I discovered the t-stat that was in there was letting water by in the closed position. So I put in one that I'd pulled out before.
Once that was in, I found that water was getting past the t-stat.
I checked this by pouring water into one of the inlets and watching it pour out the other side.
I have pics and video of this that I'll put up sometime.
I've plugged the weep hole in my t-stat, so there shouldn't be any water getting by. In a un-modded t-stat, some water would be able to get by it.
With the 'new' t-stat in it, the symptoms are still the same. *maybe* slightly improved, but that could just be the air temps warming up.
Damn, this sucks! Posted Image I'm going to print off this topic and show it to the Honda mechanic at my dealer and see what he says. Maybe wasted time, but he is trianed by Honda after all...
[image: View Post]2thdr, on 31 March 2010 - 05:05 PM, said:
Damn, this sucks! Posted Image I'm going to print off this topic and show it to the Honda mechanic at my dealer and see what he says. Maybe wasted time, but he is trianed by Honda after all...
I'll let you know if anything good...
Have you changed your t-stat yet? Many people including myself have been in a similar position as tx_vfr (cold running/crappy mpg)and that fixes the problem. Of course, that solution has not worked for tx_vfr unfortunately but he is in the minority with regards to solving the cold running problem.
[image: View Post]swimmer, on 31 March 2010 - 05:46 PM, said:
[image: View Post]2thdr, on 31 March 2010 - 05:05 PM, said:
Damn, this sucks! Posted Image I'm going to print off this topic and show it to the Honda mechanic at my dealer and see what he says. Maybe wasted time, but he is trianed by Honda after all...
I'll let you know if anything good...
Have you changed your t-stat yet? Many people including myself have been in a similar position as tx_vfr (cold running/crappy mpg)and that fixes the problem. Of course, that solution has not worked for tx_vfr unfortunately but he is in the minority with regards to solving the cold running problem.
I will second that motion as well. Swap the t-stat first, if that doesn't work, join me in our head-banging against this here wall...
Haven't done it yet...I'm not very handy with a wrench. Added after market pipes to my cruiser and change my oil, but that's about the extent of my expertise. Of course the shop wants about $400 to change a t-stat. I've looked at the excellent write up on changing it, but I don't want to eff it up...
[image: View Post]2thdr, on 31 March 2010 - 06:14 PM, said:
Haven't done it yet...I'm not very handy with a wrench. Added after market pipes to my cruiser and change my oil, but that's about the extent of my expertise. Of course the shop wants about $400 to change a t-stat. I've looked at the excellent write up on changing it, but I don't want to eff it up...
Its really not that complex. Follow the write-up, and you'll be fine.
I'd offer to help, but WA is a bit of a commute away from TX! :rolleyes: I'd be willing to race any Honda tech doing it! :cheerleader:
I'm using a modified honda civic t-stat and my 5th gen holds at 168F when its cold outside and on the highway. I block the oil cooler and it'll hold at 172F. I know the t-stat isn't stuck open cause it doesnt take forever for the bike to warm up like it did when the stock t-stat was stuck open. It hits 220F no problem with stopped traffic and I never see it go over 225F.
Warms up fine, it just can't hold temp when on the highway and its cold outside.
I have the same problem on my 06'. This is the second winter I have owned the bike and I know for a fact that the temp used to stay around 170 deg on cold days. Now I am lucky to hit 160. On freezing and below freezing days I am lucky to see 140 deg on the gauge. I ride the bike everyday to work (25mi each way) and I have noticed a drop in fuel mileage as well. I have a new t-stat waiting to be installed, but it's location is a problem. I am an auto mechanic and fixing my own vehicles is a severe inconvenience. My VFR has needed constant repairs, very unreliable. Makes me wonder if tx_vfr has a crack or something that is causing the coolant to bypass the thermostat. We'll see what happens after the t-stat replacement, if I ever get to it. :cheerleader:
[image: View Post]sunbugone, on 03 April 2010 - 11:40 PM, said:
I have the same problem on my 06'. This is the second winter I have owned the bike and I know for a fact that the temp used to stay around 170 deg on cold days. Now I am lucky to hit 160. On freezing and below freezing days I am lucky to see 140 deg on the gauge. I ride the bike everyday to work (25mi each way) and I have noticed a drop in fuel mileage as well. I have a new t-stat waiting to be installed, but it's location is a problem. I am an auto mechanic and fixing my own vehicles is a severe inconvenience. My VFR has needed constant repairs, very unreliable. Makes me wonder if tx_vfr has a crack or something that is causing the coolant to bypass the thermostat. We'll see what happens after the t-stat replacement, if I ever get to it. Posted Image
Justin
I'd ditch the Honda coolant. Too many models years have the t stat issue, for it to be a bad batch of tstats. I'm of the opinion Honda's own coolant is causing a chemical issue. I dumped the honda coolant when the bike was brand new for prestone mixes with anything. 70,000 mile no issue.
I pulled the right fairing off this morning and thought that I could get the thermostat out the side of the frame. I was right! I didn't have to remove the gas tank or anything else. I have some special tools that I use on cars that worked well. You can get both bolts out and sneak the thermostat out the side. All told it took about 1 1/2 hrs. All you really need is a snap-on 8mm swivel socket and a Wurth 6mm flexible hoseclamp driver. When I got the thermostat out, it was no surprise, stuck wide open and corroded. I had to grind off 6mm on the rear bolt, it was plenty long enough and mad installation easier. I changed out the factory coolant with prestone 50/50. Everything seems to work fine now
[image: View Post]chris2992, on 01 November 2010 - 03:54 PM, said:
Could there be something wrong with the T-Stat housing not sealing proper to the the T-Stat allowing coolant to circulate through the rads unwantedly.
I can't see anything wrong with the housing.
If the bike keeps acting up, which I really hope its resolved itself, I'll see about replacing the housing.
The rads are fine, and the hoses are all fine, and the t-stat works, so the only thing left is the housing.
Saw that this thread was resurrected from the spring. My problems basically resolved when the ambient air temps went up this summer. Bike would get up to operating temp faster and higher than when it was cool in the spring. Mileage improved as well. I think it's just the ECU putting in more gas when the air temps/engine temp is lower. As we all know these bikes tend to run hot in the summer, but in cooler weather not so much. my 2 cents...
[image: View Post]2thdr, on 01 November 2010 - 04:04 PM, said:
Saw that this thread was resurrected from the spring. My problems basically resolved when the ambient air temps went up this summer. Bike would get up to operating temp faster and higher than when it was cool in the spring. Mileage improved as well. I think it's just the ECU putting in more gas when the air temps/engine temp is lower. As we all know these bikes tend to run hot in the summer, but in cooler weather not so much. my 2 cents...
I was hoping that was the case with mine as well. Sadly, while the temps were better during the summer, the mileage didn't improve at all.
Last tank the morning runs were about 55F and the runs home in the afternoon were ~75F which returned a avg fuel consumption of 42mpg. All while maintaining the same engine temps its been running. Mid 170Fs.
I cant believe i missed this and im the only seeing it. TX you said twice that you are using 50/50 coolant "AND" distilled water. If this is true then you've thrown off the 50/50's mixture. You just use whats in the coolants jug. You dont add more water unless you want a different ratio of coolant to water. You have more cooling with a high water ratio to coolant.
[image: View Post]rangerscott69, on 01 November 2010 - 04:52 PM, said:
I cant believe i missed this and im the only seeing it. TX you said twice that you are using 50/50 coolant "AND" distilled water. If this is true then you've thrown off the 50/50's mixture. You just use whats in the coolants jug. You dont add more water unless you want a different ratio of coolant to water. You have more cooling with a high water ratio to coolant.
Doh! its a good thing I didn't take to writing as a profession!
I'm running a 50/50 mix. That's 50% antifreeze, and 50% distilled water. NOT a 50/50 mix PLUS distilled water.
What an aggravatin situation...Well here's something to try that might be quicker than a 2 hour t-stat swap, and we all used to do this when racing back in 125gp--put strips of duct tape on the front of the radiator starting at the bottom, add full or half pieces to adjust as necessary to reach the target temperature, easy on and easy off...
Whenever you go to a different track you have to compernsate for the elevation/altitude in both the fuel mixture and the operating temperature. Kept records in a notebook so next time knew which main jets to use and how many strips of tape, e.g. road atlanta, ambient 92F, 142 main, 1-1/2 tape, etc...
[image: View Post]rangerscott69, on 01 November 2010 - 08:38 PM, said:
Duct tape leaves it's stickyness behind.
Here's my thread I'm doing on fixing mine.
http://www.vfrdiscus...-fix-adventure/
I'll see your thread, and raise ya too.
Any sort of thin spray lubricant or mineral oil will remove the stickyness of duct tape , e.g. wd40, 3in1, MPL, etc...
After reading all this thermostat changing insanity (doing the same thing over and over and expecting different results), it occurred to me that maybe we are focusing on the symptoms (cold engine and poor mileage) and not the root cause (rich fuel mixture).
On fuel-injectionated engines the mixture is regulated by a computater in either an open- or closed-loop depending upon whether or not the lambda sensor is used. Typically during initial start and warm-up and at WOT the lambda is not used.
The basic mixture is calculationed with memory table look-ups from the input
factors: engine speed, throttle position, engine temperature sensor, and ambient air temperature sensor.
The counter-intuitive part of fuel-injection is that the computer will do the opposite of what you think it should be doing, especially in closed-loop mode.
If the temperature sensors are not working properly, (due to either an open circuit or high resistance) then the mixture will be enrichened to bring the engine temperature down, even though the instrument panel temperature gage (uses a different sensor) tells you that the motor is cold. This is a fail-safe mode for the sensors--if it is failed or reading wrong, the computer adds more fuel to the calculated mixture.
So i'm thinking that you should put a multi-meter on the temp sensors and measure their resistance when cold and hot and compare to the specs in the manual. For negative temperature coefficient sensors the resistance reading should go lower as the temp goes up.
The other thing to check is for a vacuum leak. Extra air from a leak will lean out the exhaust gases--but the lambda senses that condition, and the computer will enrichen the mixture to try to get the exhaust back to the stoicheometrical lambda value.
And it would be worth checking the throttle position indication switch or sensor as i've seen these go bad too, but my money is on a vacuum leak or one of the temp sensors as the culprit for root cause, and to make it sportin' i'll betcha $50 on it.
[image: View Post]kennybobby, on 02 November 2010 - 10:16 AM, said:
[image: View Post]rangerscott69, on 01 November 2010 - 08:38 PM, said:
Duct tape leaves it's stickyness behind.
Here's my thread I'm doing on fixing mine.
http://www.vfrdiscus...-fix-adventure/
I'll see your thread, and raise ya too.
Any sort of thin spray lubricant or mineral oil will remove the stickyness of duct tape , e.g. wd40, 3in1, MPL, etc...
After reading all this thermostat changing insanity (doing the same thing over and over and expecting different results), it occurred to me that maybe we are focusing on the symptoms (cold engine and poor mileage) and not the root cause (rich fuel mixture).
On fuel-injectionated engines the mixture is regulated by a computater in either an open- or closed-loop depending upon whether or not the lambda sensor is used. Typically during initial start and warm-up and at WOT the lambda is not used.
The basic mixture is calculationed with memory table look-ups from the input
factors: engine speed, throttle position, engine temperature sensor, and ambient air temperature sensor.
The counter-intuitive part of fuel-injection is that the computer will do the opposite of what you think it should be doing, especially in closed-loop mode.
If the temperature sensors are not working properly, (due to either an open circuit or high resistance) then the mixture will be enrichened to bring the engine temperature down, even though the instrument panel temperature gage (uses a different sensor) tells you that the motor is cold. This is a fail-safe mode for the sensors--if it is failed or reading wrong, the computer adds more fuel to the calculated mixture.
So i'm thinking that you should put a multi-meter on the temp sensors and measure their resistance when cold and hot and compare to the specs in the manual. For negative temperature coefficient sensors the resistance reading should go lower as the temp goes up.
The other thing to check is for a vacuum leak. Extra air from a leak will lean out the exhaust gases--but the lambda senses that condition, and the computer will enrichen the mixture to try to get the exhaust back to the stoicheometrical lambda value.
And it would be worth checking the throttle position indication switch or sensor as i've seen these go bad too, but my money is on a vacuum leak or one of the temp sensors as the culprit for root cause, and to make it sportin' i'll betcha $50 on it.
I don't have my SM with me, but I don't recall there being multiple engine temp sensors on my '02. I have not physically checked the temp sensor with a multi-meter, but I have confirmed that the temp showing on the dash, is the temp of the water in the radiators, using a laser temp gauge.
the bike is running flawlessly, save for the engine temp, so I hesitate to suspect any of the other sensors.
The next thing I'll check will be the thermostat housing itself for cracks/leaks/etc
Pull one of your O2 sensors and check it against mine in my 5th gen thread. I'm going to go get an O2 socket tomorrow cause the second one I cant get a wrench to. Gonna replace them with some universal Bosch O2's.
[image: View Post]tx_vfr, on 03 December 2010 - 11:46 AM, said:
I dug through the FSM and there is only one Engine Coolant Temp sensor.
I'm beginning to wonder if I should fault the MAP or IAT sensors.
Any luck with this mpg issue?
I have a similar situation, but I'm hopign it's just the plugs. I was at 23mpg on my '02, swapped thermostats and got up to 29mpg with the temp running correctly. I'm hoping the open t-stat fouled the plugs which I'm in the process of replacing now, I just have to get the bike back togethetr now. good info on here as to other possible causes of bad mpg other than tstat. If fouled plugs aren't my issue I'll have to give the vaccum hoses a run through and check the wax unit.
End of thread · 83 posts recoveredWayback Machine snapshot 8 Oct 2012