Need some quick help with an idle problem

W

Wanna XJ

NAXJA Forum User
Location
NWGA
Trying to help my nephew trouble shoot and hopefully fix whatever is causing him to stall out when coming to a stop and the RPMs drop. He has to keep his foot on the gas a bit when coming to a stop at a red light or stop sign which isn't the safest of things to have to do, especially for a kid.

Just looking for a couple obvious first things to check out and would appreciate a couple pointers here.

Thanks
 
We working on a XJ here? If so take the IAC out and clean it and the throttle body. The IAC is a round can with a plug into the side of it, is located at the front of the TB on a RENIX and to the back of the TB on a HO.

Do this with the key off, and do not turn the key on while the IAC is out.
 
Yep, its an XJ. Anything to watch out for when doing this in particular. How does it come off and can I just use throttle body spray cleaner?
 
Wanna XJ said:
Yep, its an XJ. Anything to watch out for when doing this in particular. How does it come off and can I just use throttle body spray cleaner?
Click to expand...

Yes, there are 2 torx head screws holding it in and there is a "O" ring around the mounting surface to seal in vacuum. I use seafoam and a toothbrush to clean them with. The pintle is most likely coated with crud.
 
spray cleaner should be fine but as ^^ said, a toothbrush makes quick work of it

look closely for any vacuum lines that are cracked/dis connected while you're in there.
 
What year XJ? the 87-90 will have the IAC at the front of the throttle body towards the front of the Jeep, it will be a round can with a molded in 2 wire plug and 2 screws holding it in. On the HO it is facing the firewall but looks the same.
 
thanks guys

I'll give this a try. Not sure if it is the problem or not, now he is telling me it doesn't do it as bad when its warmed up so I guess we will see.
 
Thats a newer model than I was suspecting. Most likely its the culprit but it could be several things. Its hard to diagnose over the net.
 
did you replace the battery recently? as in... the last few hours/day? has the jeep been sitting dead for a while?
 
if you're jeep has been sitting dead for a while and you replaced the battery or even an alternator for that matter... it may have to relearn the idle.
 
Nope but it is a bit slow to start. I got the idle control unit off and cleaned it up. Still won't idle right at cold start up BUT I did discover if you will hold your foot on the gas just right so to maintain about a 1000 rpm idle for 20-30 seconds it then will idle. It's like the ICV takes a while to kick in but that doesn't really make sense. Any ideas with this one?
 
Wanna XJ said:
Nope but it is a bit slow to start. I got the idle control unit off and cleaned it up. Still won't idle right at cold start up BUT I did discover if you will hold your foot on the gas just right so to maintain about a 1000 rpm idle for 20-30 seconds it then will idle. It's like the ICV takes a while to kick in but that doesn't really make sense. Any ideas with this one?
Click to expand...

I'm more familiar with the RENIX models but there is a latch relay in the distribution box for RENIX IAC. It sets the IAC in a start position at shutdown. I don't know how its controlled on the late models, could be done by the ECU.

You may want to try a new IAC.
 
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