High idle when parked.

[SFXJ125]

Hi gents, I looked in the OEM section for a solution but couldn't find my exact symptoms, similar...so I'm posting here for y'alls help.

I had a normal drive to work except for when I put jeep in park the idle speed jumped to 1500 or so. Turned jeep off and went inside. Several hours later I started her up to go to grocery store(cold start) and no issues except when I parked at grocery store, high idle again. Turned her off, bought my stuff and drove home, no issues on start up or park this time.

I was thinking maybe TPS, IAC-pretty sure it's not vacuum cause I checked this already with O-Gauge and fixed my heat issue. Anyways, as mentioned earlier all the idle issues ppl on forum were having dealt with TPS or IAC but can't find anyone whose had the issue when in park-normal driving seems fine.

Also, how long should it take idle to decrease from 1000 startup to 650-750? I know I'm prolly forgetting something, been a long day. Thanks in advance guys! Just wanted to hear some opinions before I go cleaning/testing and possibly screwing up the electronics.

Scott

 

[YELLAHEEP]

Ugh...... newbies....... :banghead:



We need to know the year of the XJ, if the engine is a 4.0 or 2.5, auto or manual trans, any performance mods done to it....... kinda important stuff ya know?

I guess we can assume it's an auto since you mention putting it in park. :thumbup:

 

[SFXJ125]

Yeah sorry, 97 4.0, no mods

 

[YELLAHEEP]

'97....... I was afraid you were gonna say that.

Have you noticed any changes/issues with the shifting of the transmission? My '97 had a high idle that would take seemingly forever to drop from 1100 rpm to normal when in park. Put into reverse or drive it would go to normal idle in gear.

That progressed to a high idle that never went away when in park, and a rough, low idle and eventually stalling when put into gear.

I tried swapping on a known "good" throttle body assembly to rule out the TPS, IAC and MAP. Ran the same.

Mine ended up being the TCM (trans control module). Of course....... the TCM for '97 was unique for that year only. Nothing else fits/works. Made it hard to find.

I assume you don't have a check engine light showing at this time right?

I have a particular hatred for the '97 model year........

 

[SFXJ125]

Haven't noticed anything other than when it's put in park and this is the first time it has happened. Unless you think that upon a cold morning start ideling from~1100 to~750 taking a bit, is unusual. Is this normal? If so, how long does it or should it take?

This is the first time it has happened to me so I'm on the alert for other strange actions/noises now. TCM expensive? Hard to change?

I'm going to clean TB, TPS and IAC with some throttle body cleaner tonight and see how she reacts in the morn. Any suggestions/warnings on this? Seems pretty easy enough.

No check engine light as of yet. Thanks, will update tomorrow.