Troubleshooting Help

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tbailey1532

New Member
Joined
Apr 9, 2024
Messages
4
Location
Michigan
Well I’m stumped I have a ‘99 TJ with the 4.0 and manual trans. I know little of the history on it, I bought it at an auction where it had sat in a field for a long time I threw a new battery in it and it fired up, long crank time but drove it home. It ran rough so I gave it a tune up and had no problems ran and idled great. Drove it for a few months put a few thousand miles on it and then it developed a hesitation around 2,000 rpm once I got it past that had no problems. It got progressively worse over a couple weeks and was throwing no codes. Got bad enough it developed a misfire got so bad it had almost no power had to stay in low gear high rpm just to limp home. Got home and couldn’t get it to start again. Below is a list of everything I have replaced. Any advice please fire away.

Fuel pump
Upstream O2
Tune up
3 new fuel injectors
PCM
TPS
MAP
Throttle Body
Also cleaned all grounds and checked all connections.
 
Possible plugged catalytic converter.

Can't remember if 97s have an external fuel filter under the Jeep like a YJ or not that could be plugged.
 
Check fuel pressure and I second plugged cat.

Just because it's new doesn't mean you can rule it out... welcome to the new normal of shit parts.

-Mac
 
All plugs. I replaced the 1 3 and 5 injector because I pulled the whole rail and stuck each injector in a water bottle and had someone crank the engine over and it looked like they weren't spraying as much so I just assumed from sitting they might have been clogged up
 
tbailey1532 said:
All plugs. I replaced the 1 3 and 5 injector because I pulled the whole rail and stuck each injector in a water bottle and had someone crank the engine over and it looked like they weren't spraying as much so I just assumed from sitting they might have been clogged up
Click to expand...

As in “what brand and model of plugs did you buy and install to replace the spark plugs that were in the Jeep?”
 
Champion Plugs. I worked on the last couple of days pulled all the tape off the wires and inspected them and did a continuity test and all the wires are good but still can't figure out the problem. I did discover that if I create a vacuum leak that I can get it to start but still has that bad misfire.
 
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