Lowrange2
NAXJA Forum User
- Location
- Abbeville, SC
Gentlemen,
I'm about to lose my mind dealing with this thing.
I've had this issue for a while now but it's become worse in the last month.
This is on my wife's 98 XJ Sport 4.0.
This started happening occasionally about 6 months ago usually only on a cold start. Within the last 2 months it's started doing it every time it's started after it sits for 30 minutes or so.
The Jeep runs perfect, except for the following: When I start it up, no matter whether the engine is warm or cold as soon as I start to drive away I get plagued with the engine misfiring. The more gas I give it, the worse it seems to get, falling on it's face and barely able to accelerate. Giving it gas results in the engine backfiring. By the time I get to the stop-sign at the end of my street it sits and idles, still misfiring, but will all of the sudden "fix" itself and idle perfectly. After that happens, I know that I'm ok to drive. The car will run perfect for the rest of the trip until I stop again. I can literally watch the idle bounce around during misfire and then when it fixes itself it revs up a bit and that pins itself right around 700rpm where it then idles perfectly.
If I happen to be moving when it starts chugging/missing, I can floor it to fix the issue, but if I give it any other gas aside from WOT it backfires.
While it's missing I obviously smell fuel.
If I start it and let it sit and idle for a while it goes thru the same cycle without ever touching the throttle. Start Engine, runs fine for 30 seconds, starts misfiring, misfires for ~1 minute (While fluctuating rpm between 500rpm and 1000rpm), Jumps up to 1500rpm then settles into ~700rpm then runs perfectly.
-My Check Engine Light is not on, and I did scan for pending codes... no codes are found.
-I've replaced the plugs
-It has a new fuel filter and fuel pump.
-New CPS last year.
-I've tested every sensor that I can.
Anyone solved this issue?
New CPS has gone bad? Coil? Something to do with open/closed loop system in PCM? O2 Sensor?
I don't usually start threads like this but I've about had it.
Thanks in Advance, Andy
I'm about to lose my mind dealing with this thing.
I've had this issue for a while now but it's become worse in the last month.
This is on my wife's 98 XJ Sport 4.0.
This started happening occasionally about 6 months ago usually only on a cold start. Within the last 2 months it's started doing it every time it's started after it sits for 30 minutes or so.
The Jeep runs perfect, except for the following: When I start it up, no matter whether the engine is warm or cold as soon as I start to drive away I get plagued with the engine misfiring. The more gas I give it, the worse it seems to get, falling on it's face and barely able to accelerate. Giving it gas results in the engine backfiring. By the time I get to the stop-sign at the end of my street it sits and idles, still misfiring, but will all of the sudden "fix" itself and idle perfectly. After that happens, I know that I'm ok to drive. The car will run perfect for the rest of the trip until I stop again. I can literally watch the idle bounce around during misfire and then when it fixes itself it revs up a bit and that pins itself right around 700rpm where it then idles perfectly.
If I happen to be moving when it starts chugging/missing, I can floor it to fix the issue, but if I give it any other gas aside from WOT it backfires.
While it's missing I obviously smell fuel.
If I start it and let it sit and idle for a while it goes thru the same cycle without ever touching the throttle. Start Engine, runs fine for 30 seconds, starts misfiring, misfires for ~1 minute (While fluctuating rpm between 500rpm and 1000rpm), Jumps up to 1500rpm then settles into ~700rpm then runs perfectly.
-My Check Engine Light is not on, and I did scan for pending codes... no codes are found.
-I've replaced the plugs
-It has a new fuel filter and fuel pump.
-New CPS last year.
-I've tested every sensor that I can.
Anyone solved this issue?
New CPS has gone bad? Coil? Something to do with open/closed loop system in PCM? O2 Sensor?
I don't usually start threads like this but I've about had it.
Thanks in Advance, Andy
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