Hey, everyone.
I have been having some intermittent issues with my 1997 4.0 Manual TJ since June. I could really use some help.
Sometimes it runs great, sometimes it runs really rough. Sometimes when I am coming to a stop, take my foot off the gas, put it in neutral, it idles very rough and the RPMS and fuel pressure drop until the check gauges light comes on. Sometimes the RPMs rise as if it is opening the throttle all by itself. Sometimes when I’m driving and my foot is on the gas I can feel the Jeep stutter and hesitate like it’s coughing. Sometimes when I try and start it, it takes a very long time (2-6 cranks) to start. Sometimes when I try and start it, it backfires loudly like a gunshot. Sometimes when I try and start it, it starts, but if I take my foot off the gas it stalls immediately. However, sometimes it runs great and smooth. I can’t seem to find any rhyme or reason. It doesn’t matter if it’s a cold start or if it’s been running for hours.
Things that I’ve done to try and fix it:
Replace the fuel pump
Clean the throttle body and IAC.
Replace the IAC valve- twice.
Replace the upstream oxygen sensor
Replace the fuel injectors
Replace the MAP sensor
Replaced my brake booster to fix a vacuum leak.
I think I replaced another sensor at the same time but I don’t remember what it was.
I hooked up a code scanner a few days ago and I didn’t get any codes.
Today I used the key dance method and got the following codes: 12 27 27 27 43 27 21 52 55.
Currently it’s in the garage with the battery disconnected. Hopefully that will clear the codes and then I’ll drive it for a bit and check again. I also want to check the fuel pressure, but currently I don’t have a gauge to do it.
Maybe I just bought crappy fuel injectors or something. I don’t know.
I’m really at a loss here. Please give any thoughts you may have- it’s my daily and currently I don’t feel good or trusting enough about driving anywhere.
Thanks.
I have been having some intermittent issues with my 1997 4.0 Manual TJ since June. I could really use some help.
Sometimes it runs great, sometimes it runs really rough. Sometimes when I am coming to a stop, take my foot off the gas, put it in neutral, it idles very rough and the RPMS and fuel pressure drop until the check gauges light comes on. Sometimes the RPMs rise as if it is opening the throttle all by itself. Sometimes when I’m driving and my foot is on the gas I can feel the Jeep stutter and hesitate like it’s coughing. Sometimes when I try and start it, it takes a very long time (2-6 cranks) to start. Sometimes when I try and start it, it backfires loudly like a gunshot. Sometimes when I try and start it, it starts, but if I take my foot off the gas it stalls immediately. However, sometimes it runs great and smooth. I can’t seem to find any rhyme or reason. It doesn’t matter if it’s a cold start or if it’s been running for hours.
Things that I’ve done to try and fix it:
Replace the fuel pump
Clean the throttle body and IAC.
Replace the IAC valve- twice.
Replace the upstream oxygen sensor
Replace the fuel injectors
Replace the MAP sensor
Replaced my brake booster to fix a vacuum leak.
I think I replaced another sensor at the same time but I don’t remember what it was.
I hooked up a code scanner a few days ago and I didn’t get any codes.
Today I used the key dance method and got the following codes: 12 27 27 27 43 27 21 52 55.
Currently it’s in the garage with the battery disconnected. Hopefully that will clear the codes and then I’ll drive it for a bit and check again. I also want to check the fuel pressure, but currently I don’t have a gauge to do it.
Maybe I just bought crappy fuel injectors or something. I don’t know.
I’m really at a loss here. Please give any thoughts you may have- it’s my daily and currently I don’t feel good or trusting enough about driving anywhere.
Thanks.
