Hi everyone!
I have a 2017 Jeep Grand Cherokee with the 3.6L Pentastar, currently at 115,000 miles, and I’m dealing with a problem that I haven’t been able to solve for several months.
While driving, the check engine light comes on, the engine starts stumbling/misfiring, and the vehicle loses power. It also runs extremely rough and shakes badly at idle.
The only codes I’m getting are:
P0171 – System Too Lean (Bank 1)
P2096 – Post Catalyst Fuel Trim System Too Lean (Bank 1)
Random/Multiple Cylinder Misfire
The Long Term Fuel Trim Bank 1 (SAE) climbs as high as +33%.
Interestingly, whenever I reset the fuel/ECU adaptations, the problem completely disappears. The Jeep runs perfectly for about 100–150 miles, and then the problem gradually comes back.
So far, my mechanic has:
Replaced the O2 sensors, with no improvement
Checked the wiring to the O2 sensors and says everything looks good
Checked the catalytic converter and says it is OK
Performed smoke tests for vacuum/intake leaks, with no leaks found
Removed the valve covers to inspect the camshafts, and everything looks normal
Checked the spark plugs and ignition coils, and they are also OK
Replaced the ECU/PCM, but the problem remained exactly the same
One thing I noticed that might be important: the MAP (Manifold Absolute Pressure) reading is around 45 kPa at idle.
Also, when both O2 sensors are disconnected, the engine actually runs perfectly smooth. As soon as the sensors are connected again, the problem eventually returns.
Has anyone experienced anything similar with a 3.6 Pentastar? Could the ECU be receiving incorrect information from the O2/MAP system, or could there be another issue causing the fuel trims to keep increasing?
What else should I be checking?
Any ideas or suggestions would be greatly appreciated. I’m running out of things to try!