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Our 99 trooper has codes P0137;P1171;P0300 (misfire, lean, low #2 O2 sensor signal) and no power. They will clear and come right back if reved. Now it's idling only on a few cylinders, mostly the pass bank and won't go over about 1200 RPM . (Pull wires on pass bank and it dies - driver's side makes almost no difference)

It's running 40 psi fuel pressure with a new FPR, but the FPR made no change and it the trooper won't even move. New front of cat O2 probes made no difference, and new mass flow sensor also changed nothing.

I can't seem to find the famous intake manifold leak. D :( o these occur in any special area (pass side,driver's side, front, rear?)

Is there a way to time these engines, or are they pre-programmed?

Also, was wondering if the timing belt could have slipped on the pass bank?

Any help appreciated. Thanks
Got about 70,000 miles
 

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Im a VW tech , at heart, and they go out all the time in the 99 and newer ones.
So often that VWOA has done a hush hush warranty on them if they fail before 70K.
 

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Code0137 is the downstream O2 sensor on bank 1(passenger side). So changing the upstream sensors wouldn't be expected to have any effect. I really doubt it is a sensor problem but to truly rule this out as a problem you could swap the new upstream with the old downstream sensors and see if the code changes/problem moves.

I also doubt it is a coil problem. VW problems not withstanding, Isuzu coil pack don't seem to fail out of the blue. Even if they did I really, really doubt all 3 on one bank would have failed at the same time.

No, you cannot time your Trooper the computer does that work.

If it was an individual cylinder problem then pulling the coil wire to that cylinder should result in no change. Whereas, pulling any other coil wire would result in an engine going from 5 to 4 cylinders which should be easy to detect. Therefore while it could be an individual cylinder problem like an injector or coil pack I doubt it. But again if you really want to rule this out you could swap the passenger side coil packs, and injectors for that matter, to the driver side.

I vote for the IMG which many people could not detect using a typical leak checking procedure. My advice is to go slow and carefully listen for the idle change that and do a search here and see what did/didn't work for other people.
 

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Sounds like tomster has more isuzu info then me .
I would do the swap and see if it changes the code.
Its a free test and wont take long to do.
It would at least rule them out .
 

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I just ended up replacing a fuel injector on my '99 that had stuck open. You may have one that is clogged. First, get a spark plug tester and check each coil pack to ensure they are functioning and getting spark. Then, pull each plug to see if you can isolate the bad cylinder(s). In the alternative, do what someone else suggested, which is remove each coil pack power source individually. When you find one that does not affect the idle quality, you have found your cylinder. On mine, it was real easy to tell.

If it's unclear or it seems to be changing, or it seems to be multiple cylinders, it may be something global like the IMG.

Regards,
Tom
 
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