Hello guys! I have a 1991 Jeep Comanche 4 wheel drive with the 4.0 HO MPI engine…
This is a new occurrence. When I press down the accelerator the engine takes a very long time to accelerate. It is as if I am hauling a very heavily loaded trailer. I have checked everything I can from dragging brakes, to a plugged catalytic converter to the MAP sensor, TPS, idle mixture controller, O2 sensor, checked the vacuum at idle and when driving, fuel pressure at the rail and pump at idle and driving, etc, and still I have this problem. I cannot climb a hill even at a 1% grade without losing speed. It is as if the the effective throttle range is only the first 25% of throttle and after that it has no effect. I also notice that if I press the throttle half way or even fully depressed the engine coolant temp rise about 25-30 degrees. Spark plug check showed that the engine is running lean qualifying the reason for the increase in coolant temps. Any help would be greatly appreciated.