Sputtering problems
04-21-2017, 04:44 PM
#1
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Join Date: Apr 2017
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Model: Cherokee
Sputtering problems
I have a 99 cherokee 6 cylinder that stumbles at normal operating temperatures. Replaced fuel pump relay, distributor cap, crankshaft position sensor, coolant temp sensor, ecu/pcm and intake air temp sensor. Still stumbles at operating temperatures. Runs fine and starts fine till it reaches operating temperatures. Any help would greatly be appreciated tired of throwing money away.
04-21-2017, 06:32 PM
#2
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Join Date: Nov 2010
Location: In the middle of Minnesota!
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Year: 1999
Model: Cherokee
Engine: 4.0
1. Ever seen a check engine light? If so, you must pull codes for clues/guidance.
2. When was the last tuneup? Fresh Champion plugs, quality plug wires, distributor cap and rotor.
3. Test your map sensor AND fuel pressure. If it runs good when cold, it is getting a "richer" mixture. The map sensor is also involved with fuel air ratio. You may not be getting the correct fuel/air ratio when warm. And testing fuel pressure is NEVER a bad idea. For a 99, you need 49 psi, plus or minus 5 psi.
2. When was the last tuneup? Fresh Champion plugs, quality plug wires, distributor cap and rotor.
3. Test your map sensor AND fuel pressure. If it runs good when cold, it is getting a "richer" mixture. The map sensor is also involved with fuel air ratio. You may not be getting the correct fuel/air ratio when warm. And testing fuel pressure is NEVER a bad idea. For a 99, you need 49 psi, plus or minus 5 psi.
04-22-2017, 02:56 AM
#3
CF Veteran
Cam position sensor is quite prone to temperature issues. Also check plug wires carefully, observe at night... and check fuel pressure.
