Rileyjc

I have a really bad misfires and am at a loss as to what to do to fix it. I have followed this thread and have done all it's suggestions. I'm not really sure what is wrong and could use some help.
https://www.cherokeeforum.com/f2/200...isfire-214848/

I have tested the coil pack, checked the spark plug, changed the cps sensor and tested it, done a compression test, cleaned up all the grounds, and tested the resistance on the fuel injectors. I am pretty sure injectors 3 and 5 are bad but the rest were fine.

Heres my rests of the compression test and Injector test:
Cylinder 1 Compression: 130
Cylinder 2 Compression: 130
Cylinder 3 Compression: 130
Cylinder 4 Compression: 135
Cylinder 5 Compression: 140
Cylinder 6 Compression: 130

Injector 1 Resistance: 13.2
Injector 2 Resistance: 13.2
Injector 3 Resistance: 60.8
Injector 4 Resistance: 13.2
Injector 5 Resistance: 17.0
Injector 6 Resistance: 13.2

Any help is appreciated!!!

Roler

Have you checked for codes?

Easy (free) to do and if it shows misfire cylinder 3, I think you might have answered your own question..

Rileyjc

Hello, Roler
The codes came up as P0300, P0302, P0306, which are all misfire codes and P0205 which says Injector circuit/open on cylinder 5, and P0432. I went ahead and bought a new set of injectors and am just wait to get them. Is there anything besides the injectors I can test to see if it is the problem or should I wait until after I replace them.

BlueBalls

Your on the right track. Start with the injectors and see what's what from there.

thelebowski69

Besides injectors i’d read out the actual connectors themselves, they’re cheap to get and splice new ones in.
I’d clear the codes, get a stethoscope (auto parts store has em for like 10-15$) and listen to each injector when you turn the motor on. Should make a crisp click if they are firing. If it sounds like nothing at all or a dull knock, then its bad. If you really want, while holding the stethoscope to the injector, unplug the connector to it and see if that changes anything in sound. This is a manual cutout, i do it on my diesel to find stuck injectors.
also check your plugs, if they are new then they should all have soot on them, if its clean like its straight out of the box then its not popping off.

if its a random misfire that could be a fuel pressure issue too. Borrow a cheap test kit from auto parts store and see what your fuel pressure is at, should be around 49psi i think.

you can also use a noid light test kit for your injector connectors to see if they are working.

lastly i’ve heard of the injector harness chaffing on the back of the head, might be part of your open circuit issue. Hope this helps

SketchyGecko

I had misfire problems after a hot soak and it turned out to be bad injectors. It was 3 and 5 that were the main culprits like with yours. From what I've heard 3 goes a lot from too much heat. They make insulation shields that go in to protect them, I think they put out a TSB for the heat shield to be installed because it was a frequent problem. If you do wind up deciding to replace injectors, be careful, I got some "Bosch OEM" injectors that turned out to be knock offs. Only lasted about 10-15k. Second go round I got a set of 4 port Ford injectors and they have been great so far.(35k~)