Uneven Idling

engines
honda
cr-v

#1

When first started in the morning the engine oscillates between 1500-2500 RPM. Once it is warm the oscillations dampen to 1000-1300 RPM. The ECU and MAP censor has been changed. Also it seems the fuel regulator is lagging behind the throttle. So while shifting, the throttle has to be released substantially before pressing the clutch otherwise the engine accelerrates momentarilly. It has been at three different mechanics nobody can find the problem. If anybody has any suggestions it would by much appreciated.


#2

It just sounds like a classic vacuum leak.


#3

Spray some ether on the hoses(be careful not to catch yourself on fire) and see which one affects the idle. Said hose will has a leak.


#4

Is your AIC valve…I have repaired hundreds of these on Hondas…its their most common failure. You need to first check the coolant level in your vehicle…if you need to add a good amount…you will also need to bleed out the air in the system. Air in the cooling system is the most common cause for AIC valve operation issues.

The AIC valve is basically a thermostatically controlled vacume leak…the valve works off of the coolant temp sensor. WHen the coolant is cold the AIC valve opens up a vacume leak and raises your idle…as it warms up it closes that leak down slowly…thus returning your idle down to normal. What happens most commonly is that an air bubble forms in the coolant system (due to coolant loss)…this bubble basically makes it so that the coolant temp sensor…while normally submerged in coolant…is now in free air…now the coolant temp sensor doesnt know the true temp of the coolant/engine. This MUST be rectified for the AIC to do its job properly…add coolant to your radiator and use the bleed nipple to burp the collant system…you can look up this procedure on the net… If the bubble remains your idle will “hunt” all the time…rvving up and down up and down ad nauseum…THIS is your issue

A simple vacume leak via a hose will not make the idle “hunt” like you have…this is the AIC doing this…many others have had this issue as I said it is THE most common issue on HOndas…its Textbook actually… Hope this helps you.

Wouldnt hurt to check your electrical connections on these 2 items as well…unplug and replug them in to make sure they have a good connection…I think as soon as you add coolant and burp…your issue goes immediately away…but where is your coolant going is the next question…


#5

Thank you for your advice. I cleaned the AIC valve and now the idle is steady. The only problem now is that if if release the throtle and press the clutch at the same time the engine revs up as if I released the throtle too late. It is not much of a problem just annoying that I have to release the throtle before pressing the clutch.


#6

Clean the throttle body.