bornofash
NAXJA Forum User
- Location
- Las Vegas, NV
Hi there! Trying to diagnose my cylinder misfire issues that have been ongoing. I feel like I've tried almost everything and I now have a shop telling me I need a new motor which may be the easiest but also most expensive solution.
My 2000 Jeep Cherokee 4.0L inline (168k+ miles, automatic) has been running quite rough lately and the check engine light is on, again (codes listed in subject line). It takes a few turns for her to start and it takes a min or two for the idle to smooth out. More recently idle is sometimes dipping down to 250 rpm when I'm at a stop but so far, no stall.
So I bought her a few months ago and she ran fine for a bit. About a month later the check engine light came up with cylinders misfiring. I changed the spark plugs which were pretty corroded and not properly gapped. This fixed the issue for about a month when the check engine light came back and she began running very roughly. I took her to a shop where they said a couple fuel injectors were non functional. I had ALL of them replaced along with another set of new spark plugs. She ran beautifully for about another couple months, until now. I'm getting the same codes. I've swapped coils 1&2 and 5&6 to make sure they weren't the culprit. The misfire did not follow the coil. I purchased the O2 sensor that set off the code and replaced it. Code came back. The other day I pulled the throttle body and IAC and cleaned them thoroughly. I've also run seafoam through the engine. When I pulled the spark plugs they were again corroded and covered in oil. Is there something else I'm missing or is a new motor really the way to go?
This is what the throttle body and the plugs looked like when I pulled them...
My 2000 Jeep Cherokee 4.0L inline (168k+ miles, automatic) has been running quite rough lately and the check engine light is on, again (codes listed in subject line). It takes a few turns for her to start and it takes a min or two for the idle to smooth out. More recently idle is sometimes dipping down to 250 rpm when I'm at a stop but so far, no stall.
So I bought her a few months ago and she ran fine for a bit. About a month later the check engine light came up with cylinders misfiring. I changed the spark plugs which were pretty corroded and not properly gapped. This fixed the issue for about a month when the check engine light came back and she began running very roughly. I took her to a shop where they said a couple fuel injectors were non functional. I had ALL of them replaced along with another set of new spark plugs. She ran beautifully for about another couple months, until now. I'm getting the same codes. I've swapped coils 1&2 and 5&6 to make sure they weren't the culprit. The misfire did not follow the coil. I purchased the O2 sensor that set off the code and replaced it. Code came back. The other day I pulled the throttle body and IAC and cleaned them thoroughly. I've also run seafoam through the engine. When I pulled the spark plugs they were again corroded and covered in oil. Is there something else I'm missing or is a new motor really the way to go?
This is what the throttle body and the plugs looked like when I pulled them...
Last edited:
