Chadillac1982
NAXJA Forum User
- Location
- AR
My 1999 4.0L is running very rich to the point it won't idle. Put new gas in it tested sensors MAP IAC TPS ECT new plugs and wires cap rotor. Any help or questions help me get him back on the trails. -Chad
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Running rich
- Thread starter Chadillac1982
- Start date
old_man
NAXJA Forum User
- Location
- Loveland, Colorado
Could be a plugged CAT. Put a vacuum gauge on it and post up the readings at an idle, 2000, and 3000 rpm.
- Location
- Southern Maryland
What does the coolant temperature gauge show? If the computer thinks the coolant is cold it will ass-u-me the catalytic converter is cold and try to warm it up by running rich
If the temperature is in the 195-215 range, then next guess would be to swap the O2 sensor if you don't know when it was last replaced
If the temperature is in the 195-215 range, then next guess would be to swap the O2 sensor if you don't know when it was last replaced
- Location
- Minneapolis, MN
Confirm the Coolant Temperature Sensor signals are correct. Test the O2 sensors or replace them with NTK brand sensors. Most 4.0L Cherokees have a cracked exhaust manifold. This will allow fresh air to be pulled into the exhaust stream and the PCM will think the engine is running lean and add more fuel.
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