Restarted it and the same thing. Just louder the second time and goes away after some acceleration.

 

If you reset the code and it came back, there's still a problem.

 

After some research I found out it's gotta be a flex plate bolt that's loose

 

It could be a cracked flex plate if it's coming from the front of the bellhousing. Pull the inspection cover and spin the flex plate by hand, looking for any defects. If it is a loose bolt, you'll see it.

 

Thanks Steve, that makes perfect sense.

 

Did you shut it off and restart?

 

...with the volume of results when I search. I've been reading for 2 days and it seems like I'll need a few more just testing everything.

2 questions: Crank no start - I get 48lbs of fuel pressure on prime, but drops to about 42 within a few seconds. Is that low enough so it won't start?

#2) 2000 4.0 with coil rails - how can I check spark fast and easy when it's got no plug wires?

BTW, no codes, no mil problems.

We use this mostly for going up where no one else is, no multi meters or custom test equipment there, and a tow would be a helicopter pick (or just leave it there and walk out over a period of days) I get the feeling I'll never trust it to get us back after reading all the sensors and stuff that can go wrong. Luckily, it died in it's sleep in our driveway......this time.

Should have got something with a carb and points, I guess.

 

Does anyone have a procedure for changing the timing chain on a 1998 XJ 4.0?

I am more or less just trying to figure out if I will need to remove the radiator, and a general procedure

 

Gentlemen. I'm jeep dumb admittedly. I love my 2001 xj, 225k miles. She has a rod knocking I believe. So, to keep it simple, do I just have to get a 2001 long block with the 0331 head? Is there a better long block that will go right in with no mods? Used engines scare me. I'm the guy that doesn't get lucky with other people's used stuff. And I want another 225k out of her anyway. Gonna put a paint job on her, engine, and maybe even the smallest lift out there and some bumpers. Anyway, any input would be much appreciated.

 

If you are going to go the the long block route, you should get a new head with it. If you go with a rebuilt 4.0L you should still have good motor long after the body rusts away. The only thing that kills an engine is poor maintenance.

 

I did. Same noise every time, but goes away after driving

 

I haven't been following this diagnosis, but is rod knock a possibility here? I haven't personally seen it occur in a 4.0L

 

If it is like most of the Chevy, Ford, Dodge, et al engines the best way is to pull the radiator, water pump, harmonic balancer, timing chain cover, and perform the removal and replacement of said chain. If my memory serves me well You might have to loosen the first 3 bolts on the pan to remove the cover on the chain as they go into the cover from the bottom.

 

It could also be a collapsed valve lifter. I had a 1974 225 slant six that had a bad valve lifter. It would make noise for about 5 minutes after you started the engine till it pumped itself up. It would work all day after the initial start up in the morning.

 

Need some help. 99 4.0l 4wd
I started to experience a weird stumble when using cruise control the other night. reset my cruise and it worked perfectly fine. the next day when I was driving it's stumbled and revs dropped again, but kept moving and then at a stop sign it quit. did some searching and found that the TPS tends to be the most common culprit. so I tested and was getting poor voltage all the way through WOT. Installed new one, tested it and voltage was still poor which I thought was strange and this time I had a CEL at startup. . I took it around the corner to AutoZone and the scanner read two codes both pointing to TPS. So now I'm thinking I have a faulty TPS that I purchased and so I took it back and got a different one, installed that one and now my code is gone but my stumble seems like it's even worse now and it just kept cutting out in the driveway. anybody's thoughts on this? Throttle body and IAC recently cleaned. Vacuum lines? (Diagram please). Connector to TPS? Help please. Thanks.