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88 Cherokee slight misfire


NAXJA Forum User
Peabody, MA
working on the 88 and I'm now having a what i think is a soft misfire. if i hold the throttle steady at 35mph you can feel it jerking and it also seems down on power. according to my REM all the sensors look to be reading ok.

what i did to try and fix it. and or because it needed to be done was

replaced the injectors with 4 hole. flow tested and matched them. put a new fuel pump (Delphi) and regulator. new map sensor (NTK) replaced the tps (NTK) new cap and rotor and wires. rewired the injectors and removed the c101 connector. checked and cleaned grounds. and replaced all the relays.

during some diagnostics i unplugged the ecu side of the tps. didn't help. unplugged the sync sensor didn't help. but it did seem to lose sync and the engine would cut out. rpms stayed up but was not running. i don't think this is a crank sensor issue as I'm not losing rpm signal but i did buy a new one but haven't installed it yet. i have a new coil and sparkplugs on order. the spark plugs are champions and they look ok. the exhaust was also changed but not the cat. the cat is fairly new and looked ok. it still revs up so i don't think its a exhaust restriction.

when you can feel it at 35 its in 3rd with the converter locked up. fuel trims look pretty normal around 128 LT.

anything else i should look at? i do have a spare ECU but i cant imagine that is the issue. i will check the connectors on it. the one im running is from a 90 and when i got the jeep it had a reman in it already so i could try that too.