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Engine misfire
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=88&t=92874		 Page 1 of 1
Author:  yellkayak [ Sat Feb 17, 2024 3:38 pm ]
Post subject:  Engine misfire
2008 Liberty , the Jeep started misfiring , running rough , it’s noticeable at idle but gets a lot worse as it approaches 2000 rpm’s. The misfire seems to go away around 2600 rpm’s and smooths out. Does that sound like injectors or plugs or ? The check engine light did not go on.
Author:  WWDiesel [ Sat Feb 17, 2024 5:09 pm ]
Post subject:  Re: Engine misfire
yellkayak wrote:
2008 Liberty , the Jeep started misfiring , running rough , it’s noticeable at idle but gets a lot worse as it approaches 2000 rpm’s. The misfire seems to go away around 2600 rpm’s and smooths out. Does that sound like injectors or plugs or ? The check engine light did not go on.

Scan it for any stored codes.
Could be a spark plug, coil, injector issue, leaking EGR valve, vacuum leak in PVC system or in EVAP system, etc...will have to rule out each one individually using proper diagnostic tools. :wink:
Author:  MarkZ28 [ Sat Feb 17, 2024 9:51 pm ]
Post subject:  Re: Engine misfire
yellkayak wrote:
2008 Liberty , the Jeep started misfiring , running rough , it’s noticeable at idle but gets a lot worse as it approaches 2000 rpm’s. The misfire seems to go away around 2600 rpm’s and smooths out. Does that sound like injectors or plugs or ? The check engine light did not go on.

Did you get any water on your engine? The seals on the coil packs/plug boots sometimes dry up from age and heat and let water get the plug wells causing a short. Learned that after offroading and washing the engine off, number one had a dead miss. Removed the plug wires and found it, blew the water out and ran perfect again. Free repair, lol. To find out what cylinder is not firing, remove the connector to the coils one at a time, if the rpm doesnt drop and run a lit worse, you found the dead cylinder. To check the coil put a park plug in the boot and see if it sparks, youll onow the ignition part is good. Only thing it could be is fuel injector or no compression.
Author:  layback40 [ Sun Feb 18, 2024 3:10 am ]
Post subject:  Re: Engine misfire
I assume its a 3.7 gasser. If you can put a drop of diesel on each of the exhaust ports on the manifolds, you can probably see what cylinder the problem as the diesel will evaporate much slower. Once you know, try swapping the coil pack with another cylinder & see if the misfire moves with the pack.
You may be able to do a similar thing with injectors.
Have you checked the plugs? They may show the one with the miss.
Author:  yellkayak [ Sun Feb 18, 2024 12:44 pm ]
Post subject:  Re: Engine misfire
Yes 3.7 gas engine. I put a code reader on it , p302 said misfire cylinder #2 , code p 202 open circuit cyl. 2 .
I guess I’ll replace the injector.
Author:  WWDiesel [ Sun Feb 18, 2024 1:51 pm ]
Post subject:  Re: Engine misfire
yellkayak wrote:
Yes 3.7 gas engine. I put a code reader on it , p302 said misfire cylinder #2 , code p 202 open circuit cyl. 2 .
I guess I’ll replace the injector.
Have you replace the spark plugs?
Before replacing an injector, swap the #2 ignition coil with one of the other cylinders and see if the misfire (skip) moves.
If it does, replace the coil. Most likely the problem vs an injector.
or
You could also get someone with a high end diagnostic scanner to run an functionality test to see if it is an injector problem, i.e. injector, wiring, PCM, etc...
Replacing injectors requires a lot more labor vs simply replacing an ignition coil or spark plug. :wink:
Author:  yellkayak [ Sun Feb 25, 2024 10:24 am ]
Post subject:  Re: Engine misfire
I ordered injector and coil. The next time I started it it ran normal no misfire, drove it again no misfire. I’ll replace parts on 2 and save old parts.
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