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I have a 99 Jeep Cherokee Limited with a 4.0 inline 6 cyl. It has been a good ride but when you first start it up (cold start) after a few mins. it starts to idle rough, it never dies but it acts like it is running out of fuel. If you take off down the road it hesitates and backfires through the intake. If you really open up the gas it goes on with no trouble. This only happens after a cold start and only last for a few mins.(maybe a 1/4 mile or so) after that it runs just fine, until the next cold start. I have done a complete tune up. (plugs, wires, distributor cap, rotor button, air filter, oil & filter, ect.). Someone please help me with this. Check engine light does not come on. I hope I have explained this right. If you need more info please ask and I will try to explain the best I can. Oh yeah I called the parts store about a fuel filter and they said it was not serviceable. Thanks
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Welcome to the forum! I’ve had people ask me about almost the very same issue in the past and I believe the solution had something to do with the throttle body but I did some quick research and found some saying O2 sensor (I don’t subscribe to this as the O2 isn’t even active till the engine is warmed up) but I also found this TSB on a computer update.
http://www.wjjeeps.com/tsb/tsb_wj_1801001.pdf
Here’s a full list of TSB’s for that vehicle.
Hi,
Just replying to an older thread, the issue might have been solved already.
The backfiring issue is quite common in the 4.0 ltr engine of your Jeep. Since it tends to do it when in early phase of warming up, a thermal issue could be effecting this, and very often the Crankshaft Postion Sensor or. CPS is the cause. Somewhere during iits life n the 4.0 it will fail and usually with symptoms like yours, or random stalling/backfiring/no starts in the prelude to this.
Yes, O2 sensors can malfunction, but lok into checking/replace your CPS first. Its on the things to do list.Had same issue, have a 97 Cherokee.
Hi,
Just replying to an older thread, the issue might have been solved already.
The backfiring issue is quite common in the 4.0 ltr engine of your Jeep. Since it tends to do it when in early phase of warming up, a thermal issue could be effecting this, and very often the Crankshaft Postion Sensor or. CPS is the cause. Somewhere during iits life n the 4.0 it will fail and usually with symptoms like yours, or random stalling/backfiring/no starts in the prelude to this.
Yes, O2 sensors can malfunction, but lok into checking/replace your CPS first. Its on the things to do list.Had same issue, have a 97 Cherokee.
Chryslers are bad about this and I’ve found usually you need to replace both the cam and crank sensors.
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