Jiminy Chrysler

[Witsend]

Got a 2000 2.5L 4cyl Jeep Wrangler without any fault codes. No cylinder dropout or miss, Sometimes it will idle just fine and sometimes it will start (cold or warm engine) and just stall out unless you hold the throttle open some. Same thing driving it coming to a stop it will not idle and stall , and it doesn't matter if slipped into neutral to rule out a sticking TCC. Fuel Trims look normal, TP voltage ok ,Cam Crank Synch , IAT, ECT, O2 switching all look normal. The IAC valve is a $69.99 gamble. It don't have MAF sensor or any obvious vacuum leaks . Should I just slam a new IAC valve and see if the problem is fixed before proceeding to $69.99 of Scope analysis? I've been kinda looking for a reason to take the dusty cover off the counselor 2 and have a reason to run a vehicle with the garage door closed awhile. Anyone got any suggestions?

[Joe Rappa]

I'm pretty sure that IAC is the old stepper motor style. If you unplug it, it will just stay fixed in that position. On a cold start, unplug it so it idles a little high. Go for a ride. If it quits stalling, then you know you have some kind of air volume problem (or a purge valve sticking open). If it keeps stalling, you can save yourself $65.00 by not replacing it.

Joe

[Witsend]

I'm pretty sure that IAC is the old stepper motor style. If you unplug it, it will just stay fixed in that position. On a cold start, unplug it so it idles a little high. Go for a ride. If it quits stalling, then you know you have some kind of air volume problem (or a purge valve sticking open). If it keeps stalling, you can save yourself $65.00 by not replacing it.

Joe

Thanks Joe, often it won't run after a cold start either unless I press on the accelerator and nurse it awhile to idle. Maybe I could block the purge hose temporarily, road testing but think stone cold in open loop mode, that the purge valve isn't turned on until a few minutes run time. Think scan tool displays the number of IAC step , Maybe I'll take a look for IAC steps desired. There's an IAC wiggle harness wiggle test that does cycle the engine idle rpm up and down somewhat, but the IAC seemed to work then and it didn't stall during test though I did not wiggle the harness I was in my street clothes and didn't want to get greased up messing around with it)

[BRIAN617]

How dirty is the throttle body? Many idle related problems due to poor air flow around the small blade opening.

Been cleaning TBs with a hand held baking soda blaster off the Matco truck for couple years now with absolutely positive results.

Replace fewer DBW TBs too.

[Witsend]

How dirty is the throttle body? Many idle related problems due to poor air flow around the small blade opening.

Been cleaning TBs with a hand held baking soda blaster off the Matco truck for couple years now with absolutely positive results.

Replace fewer DBW TBs too.

A baking soda blaster? I think here in the States it's affectionately known as The Big Red Fire Extinguisher

[Steve6911]

For throttle bodies I have been using "a small amount" of WD-40 the wife"s toothbrush and a shop rag. Been doing that since the Ford Teflon coated TB's came out and have not had any issues.

[Witsend]

It's fixed , cleaned the throttle body and replaced the 185K IAC valve which indeed was of a stepper motor design. Snugged down all the loose rocker cover bolts on the greasy leaking valve cover. The cute young gal that owns and loves this old rough riding, noisey tire , exhaust leaking POS, is most likely going to be the one wearing the pants in the family

[Crusty]

For throttle bodies I have been using "a small amount" of WD-40 the wife"s toothbrush and a shop rag. Been doing that since the Ford Teflon coated TB's came out and have not had any issues.

LMAO-!! You mean the coated ones that the TSB's stated clearly would NOT need any cleaning and warranty wouldn't pay for throttle body cleaning anymore-??

I've been doing the toothbrush thing since the middle 80's, using GM CLEENS spray. It cuts right through ANY varnish build up and is designed to be burned in the cylinders.
I agree with you Steve. Sometimes the simplest of things works the best, regardless of how convoluted the manufacturers try to make the vehicle.

[BRIAN617]

You guys should give the baking soda blaster a try, I gave up the teeth brush method cold turkey.

I rebuild a lot of ATV/MC carbs and nothing cleans them like baking soda.

Blaster was around $50? if I remember, and baking soda is dirt cheap.

[carfixer]

that baking soda blaster is NICE......don't have one but my buddy does awesome tool