'89 Cherokee misfires when full throttle
05-14-2017, 10:13 PM
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Model: Cherokee
'89 Cherokee misfires when full throttle
I recently bought an '89 Cherokee Laredo 4.0L and it needed some work but it was a good starter. Had a 3" lift, 33" tires, etc. It stumbles when I give it heavy throttle, whether in park or under load. Replaced fuel pump, TPS, CPS, EGR and MAP sensors. Checked and cleaned all grounds and replaced battery cables. Plugs wires seem to be newer but still on my list. Still have the same issue. It has come out of it a couple of times but goes right back and misfires. Kinda stumped. Has anyone else had symptoms like this? Any help would be great!
Curt
Curt
05-14-2017, 10:14 PM
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'89 Cherokee misfires when full throttle
I recently bought an '89 Cherokee Laredo 4.0L and it needed some work but it was a good starter. Had a 3" lift, 33" tires, etc. It stumbles when I give it heavy throttle, whether in park or under load. Replaced fuel pump, TPS, CPS, EGR and MAP sensors. Checked and cleaned all grounds and replaced battery cables. Plugs and wires seem to be newer but still on my list. Still have the same issue. It has come out of it a couple of times but goes right back and misfires. Kinda stumped. Has anyone else had symptoms like this? Any help would be great!
Curt
Curt
05-15-2017, 07:44 AM
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
05-17-2017, 09:42 AM
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I followed your tips for the connectors and found some wires that were shorted together. Happened to be for the fuel pump relay and the main power to the sensors. Replaced all the bad wiring and recrimped all connection in the wire loom. It started perfectly and doesn't miss a beat. I haven't driven it yet but it sounds good and has great throttle response. I bought a Renix Engine Monitor from nickintimes (Youtube name) and all sensors seem to functioning properly. The monitor kept flashing now and then before, now it is steady. I'll keep you posted when I take it out for a drive. Thanks for the help!
05-17-2017, 04:40 PM
#5
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Join Date: Aug 2011
Location: Prescott, Az
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
I followed your tips for the connectors and found some wires that were shorted together. Happened to be for the fuel pump relay and the main power to the sensors. Replaced all the bad wiring and recrimped all connection in the wire loom. It started perfectly and doesn't miss a beat. I haven't driven it yet but it sounds good and has great throttle response. I bought a Renix Engine Monitor from nickintimes (Youtube name) and all sensors seem to functioning properly. The monitor kept flashing now and then before, now it is steady. I'll keep you posted when I take it out for a drive. Thanks for the help!