Gas Mileage In The Cold

I have an 04. I am new to the world of v-tec, so I am still learning. It seems v-tec only works after reaching an engine temp of 140 degrees. I have noticed that my gas mileage has dropped to about 32-34mpg since the Georgia cold has set in. I ride everyday. I rode in to work and the outside temp read 14 degrees on the bike. At the creek, it went blank and soon came back to read 14, then 15 until work. I watch my engine temp never get over 120 degrees. I know that I need a new thermo, but is that what is killing my mpg's. I use to get 42-45mpg. Can anyone tell me what temp thermo I need or just buy from Honda?

Id just do it right and buy it from Honda...then there's no guesswork.

And yes, a poorly functioning thermostat and just the cold air will zap your fuel economy.

I notice on the bike and in the car. Fuel mileage in the cold seems to be about 10% less than in the summer. I think it has alot to do with the crap they put in the gas more than anything else. Thoughts? :joystick:

Vtech starts at 149.

Bad thermo will toast your mileage.

Winter gas is for the birds. Literally.

yup, check your temps, you should be able to maintain a minimum of 166F all the time once warmed up. i just went through all of this... Buy the thermostat online and you'll get it much cheaper than from the dealer. Also, it you haven't replaced your air filter within the past 15k miles, might as well get one of those, too (they cost more than the thermostat...)

T-stat.

Buy lots of bandaids for your knuckles. You'll need them.

[image: View Post]cowboy, on Mar 14 2008, 01:49 PM, said:

I have an 04. I am new to the world of v-tec, so I am still learning. It seems v-tec only works after reaching an engine temp of 140 degrees. I have noticed that my gas mileage has dropped to about 32-34mpg since the Georgia cold has set in. I ride everyday. I rode in to work and the outside temp read 14 degrees on the bike. At the creek, it went blank and soon came back to read 14, then 15 until work. I watch my engine temp never get over 120 degrees. I know that I need a new thermo, but is that what is killing my mpg's. I use to get 42-45mpg. Can anyone tell me what temp thermo I need or just buy from Honda?


fix the thermo an that should get your mpg back, the difference between winter and summer should ony be a couple mpgs at the most, if the bike was functioning correctly.

the seasonally variable amount of ethanol in fuel has a large effect, and more alcohol content gives worse mileage.

Thanks everybody! I use to read another forum but they treat you like dirt when you post. Thanks again!

[image: View Post]cowboy, on Mar 16 2008, 07:43 AM, said:

Thanks everybody! I use to read another forum but they treat you like dirt when you post. Thanks again!

Is it an off-road forum? :goofy:

Bill

I've posted several times on this issue with no positive outcome...

My '02 gets REALLY BAD gas mileage as soon as it starts to get moderately cool outside... I'm talking down to about 25 mpg with outside temps of 40-60 F. I do ride a little more aggressively, which will have something to do with it, but I think the VFR FI system is really crappy. Normally, for highway riding in warm to hot weather, my bike gets mpg in the upper 30's (I think I even got near 40 once after a long day of highway miles). For city riding in hot weather, where the engine temp is consistently above 200, I get mpg in the low 30's. Then as soon as it starts to get cool outside, like below 70, my mileage quickly drops down to 30 mpg or below.

For example: this morning, it was 57 F outside, I let my bike warm up in the garage to about 160, then took off. During the 2-3 minutes of neighborhood riding, the temp got up to about 180. Then as soon as I got up to highway speed, the temp came down to 171.

I had a t-stat replacement done this summer by Pasadena Honda in Houston (money poorly spent) because it seemed like my bike was running colder than normal during the summer and the radiators would start to get hot before the bike was up at operating temp, as well as getting lower mpg. Well, the t-stat they took out looks brand new and well seated. They couldn't explain why I was getting bad mileage and even tried to tell me that 30 mpg and colder engine temps were normal???

Well, after $240 for the t-stat replacement, they wanted $140 more to do a complete diagnostic to see if they could find another problem, but after spending that much money and dealing with their lack of helpful knowledge, I said "no" and took my bike home.

The FI is obviously dumping lots of fuel into the engine, presumably to account for the colder temps (i.e. choking the engine because it's cold). The exhaust even smells very rich. But I don't know if it's running rich because the engine is too cold, or if there is a problem with the FI closed loop system (bad O2 sensor or something) that is causing it to run rich.

Any ideas on how to improve the VFR's mpg to that of other bikes, other than the standard stuff like tire pressure, clean air filter, well lubed chain, etc, when I'm being told that it's running at the correct temperature?

A few things i have figured out over time about these bikes and the cold.
- The things run rich on cold starts (really rich with my PC on it, too) and on really cold days, they can take quite a while to warm up, that entire warm-up time you are getting some seriously crappy mileage. I have found it most beneficial to try to just treat the bike like a car. I get all my gear on, get ready to go, but don't start the thing until i am backing it out of the garage. The whole time you are letting the thing sit there and idle up to temp, you are getting 0 miles per gallon, and it's dumping fuel in because it isn't going to warm up too fast at idle. Remember, it is also programed to heat up that catalytic converter down there. Quickest way to do that is with a really rich mixture. Same thing happens to your car if you start it up then let it idle on a cold day until it comes to temperature, you'll have a sharp decrease in gas mileage.
- Make a cover for one (or both of the radiators), especially you guys with bad thermostats. This is what i did when my thermostat was bad, it helped. I just made them out of cardboard, but on the inside of the right radiator, one on the outside of the left radiator (fan is in the way). This'll help keep the cold wind off of them, helping maintain slightly higher temps. Even though my thermostat is now good, i'm thinking of putting one on my right radiator again to see if it can help the bike warm a little quicker. My engine temp no longer dips below 165ish on the highway on 30F days, but if this could keep it around 170-180F, all the better. If the bike starts getting warm in stop and go or otherwise, just reach down and pull off the left cover.
-and of course, check your tire pressure. We just started dipping into the 30s a week or so ago. Checked my tires yesterday (last time i checked them was last week), both were 2-3 psi low.

I pretty much always average 39-41mpg to a tank. This last tank (refilled last night) i got about 37.5mpg. I was getting upper 20s or so when my thermostat was bad.

EDIT: Found the link from me doing my thermostat. Don't rely on dealers....
Link

The T-stat for the VFR is the same as for the ST1300. Go over to Turbo City Tom's and pick up their thermostat. That'll fix the problem. OR you could take your t-stat to a auto parts store and match it up. Just be sure to get the 180*F one.

link to the Turbo Tom t-stat: http://www.turbocity...products_id=588

I've already replaced my t-stat once, but its needing it again. I'll be doing that early next week.

[image: View Post]tpierce(MP), on Oct 23 2008, 10:22 AM, said:

A few things i have figured out over time about these bikes and the cold.
- The things run rich on cold starts (really rich with my PC on it, too) and on really cold days, they can take quite a while to warm up, that entire warm-up time you are getting some seriously crappy mileage. I have found it most beneficial to try to just treat the bike like a car. I get all my gear on, get ready to go, but don't start the thing until i am backing it out of the garage. The whole time you are letting the thing sit there and idle up to temp, you are getting 0 miles per gallon, and it's dumping fuel in because it isn't going to warm up too fast at idle. Remember, it is also programed to heat up that catalytic converter down there. Quickest way to do that is with a really rich mixture. Same thing happens to your car if you start it up then let it idle on a cold day until it comes to temperature, you'll have a sharp decrease in gas mileage.
Whenever I did the start-up-n-go method during the cold, I really noticed the bad gas mileage (25mpg). I figured it was better to actually let the bike warm up at idle for 5 minutes when I'm not pushing a bunch of gas through at 5k RPM.... warm up, then hit the road and quickly get up to 170+ F coolant temp and leaner mixture, versus cold engine, cold air flowing over it, and thus more fuel-rich mixture and more gas consumption.

Please correct me if I'm wrong...

[image: View Post]angst, on Oct 23 2008, 07:48 AM, said:

I've posted several times on this issue with no positive outcome...

My '02 gets REALLY BAD gas mileage as soon as it starts to get moderately cool outside... I'm talking down to about 25 mpg with outside temps of 40-60 F. I do ride a little more aggressively, which will have something to do with it, but I think the VFR FI system is really crappy. Normally, for highway riding in warm to hot weather, my bike gets mpg in the upper 30's (I think I even got near 40 once after a long day of highway miles). For city riding in hot weather, where the engine temp is consistently above 200, I get mpg in the low 30's. Then as soon as it starts to get cool outside, like below 70, my mileage quickly drops down to 30 mpg or below.

For example: this morning, it was 57 F outside, I let my bike warm up in the garage to about 160, then took off. During the 2-3 minutes of neighborhood riding, the temp got up to about 180. Then as soon as I got up to highway speed, the temp came down to 171.

I had a t-stat replacement done this summer by Pasadena Honda in Houston (money poorly spent) because it seemed like my bike was running colder than normal during the summer and the radiators would start to get hot before the bike was up at operating temp, as well as getting lower mpg. Well, the t-stat they took out looks brand new and well seated. They couldn't explain why I was getting bad mileage and even tried to tell me that 30 mpg and colder engine temps were normal???

Well, after $240 for the t-stat replacement, they wanted $140 more to do a complete diagnostic to see if they could find another problem, but after spending that much money and dealing with their lack of helpful knowledge, I said "no" and took my bike home.

The FI is obviously dumping lots of fuel into the engine, presumably to account for the colder temps (i.e. choking the engine because it's cold). The exhaust even smells very rich. But I don't know if it's running rich because the engine is too cold, or if there is a problem with the FI closed loop system (bad O2 sensor or something) that is causing it to run rich.

Any ideas on how to improve the VFR's mpg to that of other bikes, other than the standard stuff like tire pressure, clean air filter, well lubed chain, etc, when I'm being told that it's running at the correct temperature?


It sounds like you have something wrong that is keeping the bike in warm up mode. The VFR runs well when everything is working right. This is a complicated bike, it could be any number of things not working. I don't think you have a common problem that would be easy to diagnose on line. The most common causes would be stuck thermostat or clogged air filter, you tried that so you are in uncommon territory.

[image: View Post]Bad Boy, on Oct 23 2008, 11:45 AM, said:

It sounds like you have something wrong that is keeping the bike in warm up mode. The VFR runs well when everything is working right. This is a complicated bike, it could be any number of things not working. I don't think you have a common problem that would be easy to diagnose on line. The most common causes would be stuck thermostat or clogged air filter, you tried that so you are in uncommon territory.
Thanks for the input.

I HAD seriously considered having the stealership do the full $140 diag on the bike, but they stated that the Honda diagnostic procedure is a 2-hour job that tests everything from tip to tail... I said "um, can't you just test out the FI system and forgo all the unnecessary light-bulb-test stuff?" They said "the Honda diagnostic procedure is a 2-hour job that ...." at which point I declined.

Can anyone recommend a reputable Houston-area Honda service center?

[image: View Post]cowboy, on Mar 14 2008, 01:49 PM, said:

I have an 04. I am new to the world of v-tec, so I am still learning. It seems v-tec only works after reaching an engine temp of 140 degrees. I have noticed that my gas mileage has dropped to about 32-34mpg since the Georgia cold has set in. I ride everyday. I rode in to work and the outside temp read 14 degrees on the bike. At the creek, it went blank and soon came back to read 14, then 15 until work. I watch my engine temp never get over 120 degrees. I know that I need a new thermo, but is that what is killing my mpg's. I use to get 42-45mpg. Can anyone tell me what temp thermo I need or just buy from Honda?


bike should be over 170 degree within 2 mile and not fall below, I agree you have a stuck open thermostat

Before you guys dive into your throttle bodies to replace the thermostat, try running water wetter in your system. Getting to the thermostat is a big job, my thermo was stuck open last year, temperature wouldn't hold on highway (let alone raising when under the treshhold which seems to be 78 Celcius), I pumped out about half a liter of coolant and replaced with water wetter, then drained the whole system 2 weeks later. Engine now heats up faster, I've recently taken the bike out at sub-freezing and engine temperature was still increasing to its optimum level on the highway, it never drops below 75C no matter how cold it is.

It's worth a try.

Regards,
Bruckner

[image: View Post]Bruckner, on Oct 23 2008, 09:13 PM, said:

Before you guys dive into your throttle bodies to replace the thermostat, try running water wetter in your system. Getting to the thermostat is a big job, my thermo was stuck open last year, temperature wouldn't hold on highway (let alone raising when under the treshhold which seems to be 78 Celcius), I pumped out about half a liter of coolant and replaced with water wetter, then drained the whole system 2 weeks later. Engine now heats up faster, I've recently taken the bike out at sub-freezing and engine temperature was still increasing to its optimum level on the highway, it never drops below 75C no matter how cold it is.

It's worth a try.

Regards,
Bruckner

Well I just ordered a bottle of Water Wetter online, along with some FI cleaner. My bike seems to hold around 166-180 temps in the cold, but I just filled up again at 105 miles, and the bike took 4.5 gallons. 23MPG, which is horrible. I just went out and started the bike up, (temp read 65F outside) and within in a few min both radiators become hot. I think this is a good test to see if the thermo is stuck open??? I�ve been using the bike as a commuter to work (short 10 min ride) but from what I�ve read, should be up in the mid 30s for MPG. Tires and air filter are fine. Any other things to check? Any other ideas?

My stuck-wide open thermo reads almost exactly 100* more than the air temperature when cruising. If you're holding minimum 166 in cold weather (40 or less) your thermostat sounds like it's working.

[image: View Post]watcher82, on Nov 19 2008, 05:24 PM, said:

[image: View Post]Bruckner, on Oct 23 2008, 09:13 PM, said:

Before you guys dive into your throttle bodies to replace the thermostat, try running water wetter in your system. Getting to the thermostat is a big job, my thermo was stuck open last year, temperature wouldn't hold on highway (let alone raising when under the treshhold which seems to be 78 Celcius), I pumped out about half a liter of coolant and replaced with water wetter, then drained the whole system 2 weeks later. Engine now heats up faster, I've recently taken the bike out at sub-freezing and engine temperature was still increasing to its optimum level on the highway, it never drops below 75C no matter how cold it is.

It's worth a try.

Regards,
Bruckner

Well I just ordered a bottle of Water Wetter online, along with some FI cleaner. My bike seems to hold around 166-180 temps in the cold, but I just filled up again at 105 miles, and the bike took 4.5 gallons. 23MPG, which is horrible. I just went out and started the bike up, (temp read 65F outside) and within in a few min both radiators become hot. I think this is a good test to see if the thermo is stuck open??? I've been using the bike as a commuter to work (short 10 min ride) but from what I've read, should be up in the mid 30s for MPG. Tires and air filter are fine. Any other things to check? Any other ideas?

I have been buying WaterWetter� at the stealership. Was in Pepboys the other day and they carry it for about $5.00 cheaper, along with other Red Line products.

[image: View Post]Ryanme17, on Nov 20 2008, 08:22 PM, said:

My stuck-wide open thermo reads almost exactly 100* more than the air temperature when cruising. If you're holding minimum 166 in cold weather (40 or less) your thermostat sounds like it's working.

[image: View Post]watcher82, on Nov 19 2008, 05:24 PM, said:

[image: View Post]Bruckner, on Oct 23 2008, 09:13 PM, said:

Before you guys dive into your throttle bodies to replace the thermostat, try running water wetter in your system. Getting to the thermostat is a big job, my thermo was stuck open last year, temperature wouldn't hold on highway (let alone raising when under the treshhold which seems to be 78 Celcius), I pumped out about half a liter of coolant and replaced with water wetter, then drained the whole system 2 weeks later. Engine now heats up faster, I've recently taken the bike out at sub-freezing and engine temperature was still increasing to its optimum level on the highway, it never drops below 75C no matter how cold it is.

It's worth a try.

Regards,
Bruckner

Well I just ordered a bottle of Water Wetter online, along with some FI cleaner. My bike seems to hold around 166-180 temps in the cold, but I just filled up again at 105 miles, and the bike took 4.5 gallons. 23MPG, which is horrible. I just went out and started the bike up, (temp read 65F outside) and within in a few min both radiators become hot. I think this is a good test to see if the thermo is stuck open??? I've been using the bike as a commuter to work (short 10 min ride) but from what I've read, should be up in the mid 30s for MPG. Tires and air filter are fine. Any other things to check? Any other ideas?


Even with both radiators hot to the touch before the bike even warms up? Even with the horrible MPG? Any other suggestions or things to check before I dive in a rip out a possible working thermo?

[image: View Post]JayWalker, on Nov 20 2008, 08:42 PM, said:

I have been buying WaterWetter� at the stealership. Was in Pepboys the other day and they carry it for about $5.00 cheaper, along with other Red Line products.

I checked autozone and walmart (local stores where I'm at) and no luck. So I goggled it online and found it for $7.85 + shipping. I try not to go to the stealership here for anything.

[image: View Post]tx_vfr, on Oct 23 2008, 10:00 AM, said:

The T-stat for the VFR is the same as for the ST1300. Go over to Turbo City Tom's and pick up their thermostat. That'll fix the problem. OR you could take your t-stat to a auto parts store and match it up. Just be sure to get the 180*F one.

link to the Turbo Tom t-stat: http://www.turbocity...products_id=588

I've already replaced my t-stat once, but its needing it again. I'll be doing that early next week.

A bit of an addendum to the above post.

I put in the ST1300 t-stat in VFR and it fit just fine. But once running, it wouldn't hold operating temp. On taking it back apart, I noticed that there's a bypass hole in the side of the t-stat that apparently allows more water through then will work to keep the bike at operating temp. So I replaced it with one from Bike-Bandit specifically for the VFR and its good now.