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XJ Ask the Question Thread
04-30-2017, 03:38 PM
Herp Derp Jerp
Join Date: Nov 2011
Location: Parham, ON
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Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
2000 XJ Fed Emissions 4.0L Automatic 215k miles
Hey guys I really need some help here. I've been fighting a multiple cylinder misfire and I have 2 months to get this fixed so that I can pass emissions. It randomly shows different cylinders. It could be cylinder 5 and 6 or it can be 1,2, 4, 5, or 6. Sometimes when it throws the codes its just 5 or just 6 other times it shows all of them except for cylinder 3.
What I've done:
Checked grounds, replaced CPS, TPS, coil rail, spark plugs, O2 sensors, injectors, cleaned the throttle body and the IAC valve and checked for vacuum leaks. All parts that have been replaced are Mopar. I've not yet done a compression test but the engine doesn't actually misfire. It runs as smooth as glass. There is no sputtering, rough idle, hard starts, and it can happen at anytime sitting parked or doing 80 mph or 6 mph. I do know that it only happens after the engine has warmed up. I have been using the Torque app for codes. Here is the codes I got this morning after driving 24 miles into work and then parked idling in the work parking lot. I have ordered the Chrysler Combustion Chamber cleaner for my next step. Could the catalytic converter cause this issue?
Torque Codes:
Current Fault Log
------------------
P0300: Random/Multiple Cylinder Misfire Detected
Pending Fault Log
------------------
P0301: Cylinder 1 Misfire Detected
P0302: Cylinder 2 Misfire Detected
P0305: Cylinder 5 Misfire Detected
P0306: Cylinder 6 Misfire Detected
Any help would be GREATLY appreciated!!
Hey guys I really need some help here. I've been fighting a multiple cylinder misfire and I have 2 months to get this fixed so that I can pass emissions. It randomly shows different cylinders. It could be cylinder 5 and 6 or it can be 1,2, 4, 5, or 6. Sometimes when it throws the codes its just 5 or just 6 other times it shows all of them except for cylinder 3.
What I've done:
Checked grounds, replaced CPS, TPS, coil rail, spark plugs, O2 sensors, injectors, cleaned the throttle body and the IAC valve and checked for vacuum leaks. All parts that have been replaced are Mopar. I've not yet done a compression test but the engine doesn't actually misfire. It runs as smooth as glass. There is no sputtering, rough idle, hard starts, and it can happen at anytime sitting parked or doing 80 mph or 6 mph. I do know that it only happens after the engine has warmed up. I have been using the Torque app for codes. Here is the codes I got this morning after driving 24 miles into work and then parked idling in the work parking lot. I have ordered the Chrysler Combustion Chamber cleaner for my next step. Could the catalytic converter cause this issue?
Torque Codes:
Current Fault Log
------------------
P0300: Random/Multiple Cylinder Misfire Detected
Pending Fault Log
------------------
P0301: Cylinder 1 Misfire Detected
P0302: Cylinder 2 Misfire Detected
P0305: Cylinder 5 Misfire Detected
P0306: Cylinder 6 Misfire Detected
Any help would be GREATLY appreciated!!
No way in hell. A good healthy 4.0L will show around 40 PSI, give or take 5 PSI depending on exact oil weight and temperature. Drop by your local parts store and see if you can rent or borrow a mechanical pressure gauge. Chances are the sending unit or the plug to it is screwed (not uncommon)
04-30-2017, 05:06 PM
Newbie
Join Date: Feb 2015
Location: Alberta, Canada
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Year: 1998
Model: Cherokee
Engine: 4.0L
Does a 98 4.0L need to have it's TPS adjusted after replacement? Is there a wrong way to install it around that tab? As in does it need to be on one side or the other of the splines inside the sensor? I replaced the TPS and IAC valve and it's idling quite high (2k). Does the ecu just need to relearn?
04-30-2017, 05:45 PM
Junior Member
Join Date: Mar 2017
Location: Bakersfield, CA
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Model: Cherokee
Engine: 2.5l
No way in hell. A good healthy 4.0L will show around 40 PSI, give or take 5 PSI depending on exact oil weight and temperature. Drop by your local parts store and see if you can rent or borrow a mechanical pressure gauge. Chances are the sending unit or the plug to it is screwed (not uncommon)
Last edited by Ethan94; 04-30-2017 at 05:53 PM.
04-30-2017, 06:41 PM
Herp Derp Jerp
Join Date: Nov 2011
Location: Parham, ON
Posts: 18,251
Likes: 0
Received 12 Likes
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11 Posts
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
Does a 98 4.0L need to have it's TPS adjusted after replacement? Is there a wrong way to install it around that tab? As in does it need to be on one side or the other of the splines inside the sensor? I replaced the TPS and IAC valve and it's idling quite high (2k). Does the ecu just need to relearn?
Test it with the mechanical gauge.
04-30-2017, 06:57 PM
Newbie
Join Date: Feb 2015
Location: Alberta, Canada
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Year: 1998
Model: Cherokee
Engine: 4.0L
I disconnected the neg terminal and reconnected and it seems to be running normally again. I had an issue with the jeep stalling at idle. Would pull up to a stop and it would stumble then stall. Also had it shifting strangely last week. Both the tps and iac valve looked original so I opted to replace both. I took it for a test drive around residential streets with plenty of stops and it seemed to be running normally. CPS was replaced last summer and I haven't had issues starting it cold nor after a stall so I didn't think it would be that again.
04-30-2017, 07:00 PM
CF Veteran
Join Date: Sep 2012
Location: In a large sandbox
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Year: 1998
Engine: 4.0
Anybody have a long-term fix for securing the pressed-in (?) studs on the header panel? One of the upper ones broke free at the radiator support bracket. Superglue maybe or too brittle w/ age?
04-30-2017, 07:28 PM
No, I don't lick fish.
Should be able to just get some fiberglass resin and drown it back in... maybe some cloth if a little more reinforcement is needed.
04-30-2017, 07:38 PM
Junior Member
Join Date: Feb 2017
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Model: Cherokee
I'm replacing aftermarket lights in my jeep with new ones. I decided to just splice the wires from the old ones to the new ones. One problem, the last set of lights were connected (the wires were connected). The old lights had a red wire (but no black wire) coming off of each light, and a ground wire connected to a metal bracket. The new lights have a red wire and a black wire, but no ground wire. Am i supposed to go red to positive, black to negative? And why don't the new lights have a ground, opposed to the old lights? Should i just rewire it or use the existing wire and make a Y configuration from the battery, going to both lights? As in, one red wire from positive, going to both lights, and a single black wire going to both lights (still in a Y configuration?) any advice is greatly appreiciated
04-30-2017, 07:39 PM
CF Veteran
Join Date: Sep 2012
Location: In a large sandbox
Posts: 1,623
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Year: 1998
Engine: 4.0
04-30-2017, 08:44 PM
Newbie
Join Date: Dec 2016
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Model: Cherokee
No start
Ok so you know how when you turn your key to start and all the power goes out to supply the starter. So my 92 with a 4.0 gets stuck there. No power any where, and doesn't turn over and stays there I have to disconnect the battery to get it to reset. So far I've replaced the starter relay, auto shut down relay and the ignition switch. That last one was a bear to get to. Any ideas? Thanks.
04-30-2017, 09:31 PM
No, I don't lick fish.
Ok so you know how when you turn your key to start and all the power goes out to supply the starter. So my 92 with a 4.0 gets stuck there. No power any where, and doesn't turn over and stays there I have to disconnect the battery to get it to reset. So far I've replaced the starter relay, auto shut down relay and the ignition switch. That last one was a bear to get to. Any ideas? Thanks.
04-30-2017, 10:12 PM
Newbie
Join Date: Dec 2016
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Model: Cherokee
Wahoo
so that's awesome. I just did a little fiddling and I'm pretty sure you are correct. Not sure why the battery reset it. Or it was just coincidence. It didn't always work. Thank you very much. Also looking at it. The wires for the switch appear to have been messed with at some point. They are now routed very unfactory. Though they feed into the factory harness. Anyway it starts. Thanks again.
04-30-2017, 10:17 PM
No, I don't lick fish.
so that's awesome. I just did a little fiddling and I'm pretty sure you are correct. Not sure why the battery reset it. Or it was just coincidence. It didn't always work. Thank you very much. Also looking at it. The wires for the switch appear to have been messed with at some point. They are now routed very unfactory. Though they feed into the factory harness. Anyway it starts. Thanks again.
05-01-2017, 12:36 AM
Junior Member
Join Date: Mar 2017
Location: Bakersfield, CA
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Model: Cherokee
Engine: 2.5l
I know, but I'm asking is how would I get the oil pressure gauge to work right? Upon starting the car it pegs at 80, I didn't hook up the wires or anything. That was done when the engine was rebuilt. So I have no idea.
