Idle

[OGCollard]

Is it okay to adjust idle on my xj? Its a 2000 with efi. It dies at idle some....well a lot. I have cleaned IAC put new battery and terminals in, changed spark plugs and checked for vacuum leak somewhat. It idles a hair higher when heater is running and he says that means there prolly is no vacuum leak. I am at a loss and wonder if I can just raise the idle a bit to help it

[OldFaurt]

Is it okay to adjust idle on my xj? Its a 2000 with efi. It dies at idle some....well a lot. I have cleaned IAC put new battery and terminals in, changed spark plugs and checked for vacuum leak somewhat. It idles a hair higher when heater is running and he says that means there prolly is no vacuum leak. I am at a loss and wonder if I can just raise the idle a bit to help it

The Idle is not really mechanically adjustable, it is handled by a motorized plunger on the throttle body (IAC) that lets more or less air pass so the Computer can adjust the idle. here is a page that shows one. Little Idle thingy (http://www.omix-ada.com/idle-air-control-valve-97-04-jeep-wrangler-tj.html) Check it's connector to make sure the contacts are clean and secure. Also check the TPS throttle position sensor.

[slvmart]

Have you cleaned the throttle body, yet ? If your IAC was rather dirty it's likely that the passages on the throttle body need a good cleaning, also.

[OGCollard]

yeah. I took my throttle body off and cleaned it the same time I cleaned out my IAC. I wonder if I need a new IAC. I cleaned it as best I could but I wonder. I drove in today with the heat on and it seemed to idle just fine with no dying. I know if I turn that heat off though it is going to die at a red light.

[4.3LXJ]

I think that new IAC might be the ticket

[OldFaurt]

yeah. I took my throttle body off and cleaned it the same time I cleaned out my IAC. I wonder if I need a new IAC. I cleaned it as best I could but I wonder. I drove in today with the heat on and it seemed to idle just fine with no dying. I know if I turn that heat off though it is going to die at a red light.

There is an adjustable stop for the throttle on the front left side of the throttle body just under the lever that attaches to the cables.
there should be about a 1/4 inch of thread sticking up and contacting the lever assembly. you will need to remove the throttle body to adjust that especially if you don't have a throttle body spacer. that sets the lower limit of your idle.

Now for a few questions:
1. does it idle better after it warms up?
2. does it idle better with air conditioning on?
You said heater, did you mean defrost?
That also turns on the AC & the AC idle increase to make up for
the compressor loading on engine.
3. have you noticed a firmer brake lately?
4. Check to see if the AC Compressor is engaged
(Inner part of pulley turning) even with the heater / AC off.
If so, your AC clutch is seized up and that load is too much at idle!

All those thing impact idle!

Note, if the lower idle set screw is there and reasonably located,
you should check all the other things first, Then adjust that screw!

As far as the AIC goes, if it runs better with the AC or Defrost, the AIC is doing it's job!

[OldFaurt]

Oops!
4.0L 6 does not have valve lash adjustment!
Well THAT SUCKS!

It's the V6 that has lash adjustment.... :P
Sure, they put it on the dumb motor!

[WhileInTheWild]

Is the idle rough or just low? If rough when hot then check this out - http://www.wjjeeps.com/tsb/tsb_wj_1803103.pdf

I have that issue in my 2001 and just need to source the part or an equivalent one.

[OGCollard]

it seems to run a little rough after it comes to temp. it can sit n driveway idling fine but after about 10-20 minutes it just shuts off. does not sputter, just shuts off. it will also do it if I slow down to s stop sign quickly or if sitting at a red light. kinda nerveracking. I think it is worth checking out though. I am going to call around and see if I can find the part....

[4.3LXJ]

Just shutting off? That happens to people that have a crank position sensor starting to go bad

[WhileInTheWild]

Your issue sounds like a different one to mine, mine is only when starting hot and idling.

[OGCollard]

I thought that too about the CPS. The more I thought about it though, it seemed like there is too much of a pattern. Seems like if the CPS was starting to go out it would shut off completely at random, not just at idle. I have checked the codes if the check engine light came on when it died. It is always, always the Camshaft position sensor. But this is the second one I put in in the last 6 months and it is genuine mopar brand. I know it is not that Camshaft position sensor. maybe it is the Crankshaft position sensor. if it was I wish it would throw the code.

[4.3LXJ]

A marginal one will not throw a code. Food for thought

[XJ Wheeler]

Cps sounds right, but so does the tps (throttle position sensor). My brothers would shut off when returning to idle.

Sent via messenger pigeon - i talk, he types.

[OGCollard]

Is there a good way to test the throttle position sensor?

[OGCollard]

Buddy has a scanguage. We should be able to tell with that. Will let you know...

[OGCollard]

Well I put the scan gauge on. At full throttle it says it only opens 82%. The key is this. When slowing down or sometimes at idle it would go all the way to zero. On my non jeep at idle it sat at 2%. Plus when slowly opening and closing throttle it would jump big time. I am going to replace the throttle position sensor and see if that helps. Might be a minute though. I gotta order it cause rock auto was 50 bucks less than dealer.

[OGCollard]

So a quick update. Ordered a new IAC and TPS Friday. Genuine Mopar ones since the jeep prefers Mopar parts. Should have them Wednesday or Thursday. Will put those on and clean throttle body. If that does not cure the dying occasionally at idle or braking then it just has to be a vacuum leak.