Two issues with TJ: high oil pressure and high rpms at idle.

REDLYNER

REDLYNER

Mall Crawling Race Rig
Joined
Oct 31, 2008
Location
Mountain Island
Dropped my jeep off at a mechanics shop to get emission inspected and an oil change, but asked them to look at two issues while it was there. So far they can't figure it out, so I did some reading on my own, but wanted to get some more opinions specifically related to my two issues. This is a 2000 TJ 4.0 with 85,000 that I have owned for 8 years.

1. Oil pressure used to sit right in the middle (for over 7 years), suddenly it now shoots up to 80 while driving and drops to maybe 60 at stop lights. I also found a very small oil leak (drops in the garage and driveway). Never did this before.

Oil sending unit? Oil pump? What should I suggest to the shop?


2. High rpms. The jeep used to idle around 500rpms, both in park and while in Drive, but with no gas applied. Starting last week, the jeep now idles around 1250 in park and around 1000rpms in Drive with no gas applied.

No clue here, thoughts?
 
Clean the iac for the idle, my 97 randomly did it one day after sitting a bit. Pulled the iac and cleaned the build up off and pulled it out slightly.
Or spray some carb cleaner or something similar around the intake lightly and see if there is an intake leak.

And I would guess sending unit without testing any thing.

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they should put a mechanical gauge on it before they replace anything. you need to see what the actual pressure is before anything is done.
as far as the idle, have you had the batteries disconnected or anything electrical recently? i would lean towards the iac also, but they need to be reset after you do anything to them. the mechanic should be able to hook up a scanner and read the iac count to know if it's high or low.
 
Also cut the ac off and check ur idle then... X54444555 on hooking up a gauge. It amazes me the number of shops that throws parts rather than actually finding the problem...
 
snappy said:
Also cut the ac off and check ur idle then... X54444555 on hooking up a gauge. It amazes me the number of shops that throws parts rather than actually finding the problem...
Click to expand...

I haven't turned the AC on in 4 or 5 years..... Currently, this shop hasn't thrown anything at it, they were unable to determine the problem so far.
 
Quick update:

Vacuum leak was causing the rpm surge.

Oil Sending Unit was bad.

1.5 hours of labor plus parts and the jeep is good to go again.
 
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