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Couple of MJ ?'s (Timing, engine noise)

tchase

NAXJA Forum User
OK, couple of questions about the new MJ. First it seems a little sluggish and tends to run on a bit when you shut it off. I'm guessing the timing is off a bit. Anyone no what the timing specs are for an '88 2.5?
Also the engine is very loud in the cab. The engine sounds fine, it's just unsually loud inside. Sounds like a hole in the firewall maybe. Are there any large plugs in the firewall which might be missing?
Thanks,
Tony
 
The timing is set by the computer, you cannot adjust it. Various things can make a truck sluggish. A clogged cat can choke the life out of a perfectly good engine. Same with a bad batch of gas, clogged fuel filter or air filter, bad sparkplugs, etc. Have you checked the compression on the cylinders?
I'm not sure what type of sound you're hearing, but when I first got my 88, there was a droning sound inside the cab. Turned out that the exhaust mount was gone and the pipe was lying on the tranny crossmember. I added a generic mount to raise it up off the steel and the sound went away. Also, the manual tranny shifter boot on my 86 is torn and I can hear the engine loud and clear.
Jeep on!
--Pete

Comancheclub.com
 
Thanks again Pete,
Didn't realize the timing was non-adjustable. I haven't bothered checking compression or plugs and such since it is a shiny new rebuilt engine. Fuel filter might be worth a check though. As for the noise - tranny boot sounds like a good bet and I didn't even think of it. The mini console is MIA so I bet that's the prob. The most noticeable sound is actually the starter, sounds like it's right in the cab with you.
 
There's the shifter boot around the stick, and then another cover beneath it that screws to the tranny tunnel, which might be missing or damaged on yours.
Also, check the flange on the exhaust manifold where it bolts to the downpipe, right below the O2 sensor. One or both of the nuts may be loose and you could be getting some exhaust leakage. That may be part of the poor running condition as well (?) The nuts are 9/16" and thread onto 2 studs in the end of the manifold.
HTH,
Jeff
 
I don't mean to say that the timing is guaranteed to be perfect, just that it can't be adjusted like other engines. The computer could be setting it wrong due to bad information from a sensor. But I'd start with the easiest stuff first. Lots of problems can result in sluggish performance. Double check the condition of the spark plugs. Just because it's a "fresh" engine, doesn't mean there's nothing wrong with it. Oh, and what size tires does the Jeep have?
Jeep on!
--Pete

ComancheClub.com
 
I'll probably take a look at the thing tonight. As for exhaust leaking I'd have to say no. No exhaust noise or smell just general engine noise (and starter noise). As for the sluggishness it may be fine. I'm comparing a stock rebuilt 2.5 to my old 2.5 with K&N and dynomax, however the old one had 255/70R15's and this one has 215/75R15's. It was more the fact that it tends to "run on" a bit that made me think timing. BTW a guy drove it the other day who normally drives an '89 2.5 MJ and he thought it worked very well, but then again his engine sounds like a diesel so who knows.
 
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