Rough idle after reman engine install -
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Unread 10-05-2013, 01:14 PM   #1
Registered User
2000 WJ 
Join Date: Oct 2013
Location: Indiana, Indiana
Posts: 1
Rough idle after reman engine install

Hi everyone,

I just had a reman engine put in my WJ (2000, with the 4.0) and I can't seem to get it to idle right.

On a cold start I can feel it rumble a bit more than normal and it gets progressively worse as it warms up. After a bit of driving the idle is considerably worse. It will idle at 900-1000RPM when cold and 600-750 warmed up. There is a slight popping/puffing that is heard every 15-20 seconds too from the exhaust.

This is what I have done so far:

I checked for vacuum leaks around the intake manifold and the attached hoses.

Pulled a spark plug to verify the gap and check the deposits. It was properly gaped and had a very light white deposit on it.

Cleaned the the throttle body.

Had a small exhaust leak after the 1st o2 sensor patched.

Took it to the dealer to have the fuel timing set. It was 20 degrees off, but that didn't change the idle once timed.

The exhaust seems to be flowing fine.

I did have the CEL come on a couple of days ago for the 2nd o2 sensor (P0138), but I cleared it and it hasn't come back after ~40 miles of driving.

I already have 300+ miles on this engine and I am not sure were else I should be looking... any ideas?

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