My 2004 CRV has recently started a sporadic idling when you start it. It instantly revs up to around 3500rpm and then anywhere in between that and regular idle speed for approximately 5-10 seconds after it is started. There is no rhyme or reason as to when it will do it. It has happened on an overnight cold start and it has happened after the car has been shut off for 5 minutes and then restarted.

Twice it has revved up after putting it into reverse, to the point you have to stand on the brake pedal to keep from moving. The two times it has done this were after a routine drive, the car had been on the road for approximately 10 minutes.

My mechanic has already cleaned the throttle body and air control valve and the problem still exist . He has had the car for a week and a half and it will not replicate the symptoms for him, more than the one sporadic idle after a cold start and one time over revving in reverse. He has spoken with a Honda Service Tech and the tech told him that he had never heard of such a thing and that the vehicle should not be able to do what it is doing and the tech left it at that.

Can anybody please give advice as to what this may be. Im concerned for my family's safety and the safety of others on the road. Having a vehicle you can't trust is a terrible feeling.

 

Check coolant level to be full with no air bubbles. Bleed system as needed. Check valve adjustments or adjust them if never done. Check exhaust expansion valve this normally causes idle flux after engine is warm.

 

Thanks.

 

Look into the TPS.
It is a variable resistor
If it is faulty then it can given jumpy readings which would give bad idle and instant revving.
Only one possibility be a good place to start looking