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High Idle at Start- Whats that mean again?

2K views 7 replies 6 participants last post by  lma1973 
#1 ·
So the WJ is idling high at startup now. What is that related to again?
 
#2 ·
It is either the Idle Air control valve or the throttle position sensor. Clean the throttle body and IAC and take it from there.
 
#3 ·
Uh huh, then I did the mccc and I couldnt believe it was the same engine.
 
#4 ·
mccc?

I'll give it a thorough cleaning when I get back to the house.

So, I actually watched the RPMs today rather than just relying on my ears, it only went up to about 1,500 RPMs. I know it's not that high, but I remember is being alot lower at startup. Is that still too high?
 
#5 · (Edited)
JayIV said:
Mopar Combustion Chamber Cleaner/conditioner. Apparently there are both. I used the conditioner that requires 4 hours of saturation or overnight if possible. Did wonders for long start, rough idle and throttle response.

EDIT: Do this with engine at operating temp.
 
#6 ·
depends on how long the vehicle has been sitting when you start up you have to also remember that the computer will control idol to heat the catalytic converters as quick as possible aswell as dropping as much fuel into the combustion to heat it up as well. this is called open loop. however if you have ran the motor for some time and it's still nice and warm when you get back it should start right up hit about 1500 rpms and then drop back down to around 750-900 rpm after that if it is still sticking around 1500 when sitting at a light or after about 5 minutes or longer if engine is cold then it sounds like your idol air control is sticking most likely, i also know on the WJ the computers seem to need re programming when they start to reat high mileage as well. so that might be another idea.
 
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