4.0 TJ issues

chili84

chili84

New member
My dad has a 98 TJ with the 4.0. He's having some issues with it and replaced a number of components already. He is still having an issue and will let him explain it in his words. We plan on working on it over the next couple of days. Any help will be appreciated. Thank you!

I have replaced all the engine sensors: TBP, MAF, Camshaft position, crankshaft position, O2 (up stream), injectors, etc. It was running just fine and only occasionally throwing a P0300 code. So I read that the connectors could have corrosion so I cleaned them with contact cleaner. BIG MISTAKE! It is really bad now and throwing P0171 code. Running very rough and sometimes no power, but then just when you don't expect it, huge power burst. The head was replace a few years ago and included stronger springs and the exhaust manifold, too. The plugs, plug wires, distributor were all recently replaced.

Thanks again guys!
 
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Sometimes a 300 can be bad gas. I would run a fuel injector clean and do a decarb. Then recheck.
 
WJCO said:
Sometimes a 300 can be bad gas. I would run a fuel injector clean and do a decarb. Then recheck.
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In my old blazer I ran seafoam through the brake booster and that helped out a lot. Would you recommend that in this engine?
 
Im more a fan of trickling some ATF down the throttle body while its running to clean things out. As far as his issues goes i had a similar problem with my tj. Just be running along and it would fall flat on its face. It would all of the sudden surge back to life. There was no rhyme or reason to it either. Ended up being the plug on the coil. I ran a big zip tie around the coil and over the plug to pull it up tight, and aint had a minutes trouble since.
 
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