Evening all. My '02 has recently started to run really rough on a cold start. It's not hard to start, and it doesn't die, but for the first couple of minutes the idle speed hangs around 1000rpm and and just sounds rough. Trying to open the throttle during this time won't increase the RPMs - it just sounds like it's gaging. I assume this means it's really lean. I've checked my service manual and googled the heck out of it, and I'm starting to lean towards a WAX unit problem. Hopefully you all can fill in a couple of blanks for me.
First, what is the cold start idle speed on a 6th gen supposed to be? I don't ever remember mine jumping up to a high idle speed and then coming back down as it warmed. I do remember it idling smoothly on start-up though.
Second, Has anyone else had these symptoms? Most of the posts I found talked about high idle problems, not low.
Last, has anyone seen any WAX unit testing/adjustment information beyond what's in the service manual - which isn't much?
I'll start digging in to it this weekend, but hope to go in educated - or at least with a couple of ideas. Barring any other ideas, I'm planning to do a visual inspection of the WAX unit - to try and understand how it is supposed to work, and a starter valve sync.
Oh ya - 2002, 30k miles(24k of those in the last three years). Stock except for o2 eliminators. Runs fine once warmed and idles at 12-14k.
Thanks!
Dave
bump your idle speed to 1300 RPM. That should help.
bump your idle speed to 1300 RPM. That should help.
Thanks for the response. Already in that range when warmed, and turning it up doesn't seem to help the cold start problem.
I don't think the wax unit has much effect in the summer. I only experience a fast idle (2000-2500 rpm) when starting on cool mornings, below 60 degrees or so, ie. in late fall and winter. In the summer when its 80 degrees in the morning my startup idle is very low, around 1000 rpm. But it responds fine to throttle, so it sounds like your problem might not be the wax unit. When warm my idle is 1400-1500, indicated.
I had spare time last night so I dug in to find out how the WAX unit and Idle control works. I really wish the manual had functional descriptions of these systems - it would make troubleshooting much easier.
The WAX unit is a small linear actuator located between the throttle bodies. It is thermally operated and is heated by engine coolant passing through two fittings on it's base. When cold, less than about 100 degrees F, it is fully retracted. As the coolant warms, starting at about 130 degrees, the shaft extends, reaching full extension at about 160 degrees. :unsure: Is the WAX unit full of wax as is often stated? I have no idea. The actual internal mechanism could be hydraulic (wax, oil or other fluid that would expand when heated) or possibly thermal/mechanical - like a spring that extends when heated. Either way, it doesn't matter much since it's not serviceable. :fing02: Built into the WAX unit housing is the boss for the Idle Speed Adjustment screw. The Idle speed adjustment screw and the shaft of the shaft of the WAX actuator both interact with the starter valve plate to control idle speed as follows.
Warm engine idle is set with the Idle adjusting screw. This screw, operated by the cable and knob just above the clutch housing, pushes against the starter valve plate and sets a minimum depth for the starter valves. Turn the knob clockwise, the idle screw pushes the starter valve plate pulling the starter valves farther out thus increasing idle speed. Turn the knob counter clockwise and the starter valves retract into the throttle bodies lowering idle speed. When the engine is warm, and providing the WAX unit is working correctly, the WAX shaft is extended and the nut on the shaft does not contact the starter valve plate plate - no effect on idle speed. By my observation, when warm, the nut on the end of the WAX unit shaft should extend about 5 - 7mm beyond it's starter plate bearing - a round piece of black plastic that hooks into the starter valve plate - see the bad hand sketches below.
When the engine is cold, the shaft of the WAX unit is fully retracted, and the nut on the shaft is contacting it's bearing on the starter valve plate. In this position the starter valve plate should be pulled back such that it is not contacting the idle screw causing the starter valves to be slightly further out than the warm idle position. This is what sets cold start fast idle. This can be adjusted by turning the nut on the end of the WAX unit shaft.
When I inspected my bike last night I found that the WAX unit was not pulling the starter valve plate off of the idle stop screw. In fact, the WAX shaft nut may not have been contacting the bearing at all - difficult to tell. Also not sure if this is the result of the WAX unit nut loosening over time, some change in the WAX unit's stroke due to wear, or that to maintain a 1400 rpm idle I've had to turn the idle screw in a little further to compensate for engine wear/tune. In any event, I had no fast idle. To correct the problem I turned the WAX shaft nut in one full turn. This pulled the starter valve plate off of the idle stop screw about 1mm. By the way, this nut is one of those marked with white paint, and according to the manual should never be adjusted. Proceed at your own risk. This morning when I started the bike the Idle rose to about 1700rpm and by the first stop sign the engine temp was at 165 and the idle was back down to 1400.
I do have one final concern based on checksix's comments - The temp in my shop last night was about 75deg, and based on my observation of no shaft movement until the engine temp was about 130, I am assuming the shaft was fully retracted. However, if additional retraction can occour at cold temperatures, I'll be watching for abnormally high idle speeds this fall.
Sorry for the long post, but it really bugs me when I don't understand exactly how something works.
Sorry for the bad hand drawing :cool:
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I have (had) more or less the same problem on a �06 VFR. When it starts cold, not freezing cold, idles at 900rpm and then as temp rises, idle rises also at 1200+rpm.
I thought that it was a idle WAX unit fault. It was not.
I have changed it and checked both new and old. From ice cold temp to boiling water temp expands 6mm. The Idle WAX unit is useful only in really cold situations. If you try to adjust WAX to work in the summer then in the Winder it will idle at 3000 rpm.
Then I checked MAP sensor and IAT sensor. They were working fine. Extra attention paid to the tubes from the MAP sensor to intake hoses for cracks.
I also had a Starting Valve synch and changed the spark plugs. This helped a bit.
I also cleaned every contact in the relevant connectors.
What really made a difference, so far, was the fuel filter. After 38k miles it filtered, more or less, about 900 gallons. It was almost blocked. I changed it a couple of days ago and as a first report I can say that when cold idles at 1200rpm and then gains another 100rpm. So the problem is not completely disappeared but seems like a symptom and not real problem any more.
Next and last thing to check is the Fuel Pressure Regulator.
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Very good Dave,
Well thought out and makes sense , as long as my my bike doesnt die, 900 rpm cold start in the heat doesnt bother me, in the winter fast idle works normally.
It always been this way, and I have well over 60,000 mile,
http://www.vfrdiscus...showtopic=54277
Strange how these problems always come in pairs. From hardly ever hearing about this problem to 2 posts on it in the same week.
But definitely check the link, there's some great info there in the other thread! And we don't really want duplicate threads on this.