Rough Idle and Hesitation

[Codered]

2000 Xlt, 4.0 ohc Engine
1) On initial start after sitting all night, engine starts fine and idles fine.

2)Idle quality goes away after initial start when the engine is warm or partially warm. A) Low idle rpm=rough idle
B) Idle surges with a/c on
C) Rich fuel condition at idle " Bad smell at tailpipe
3) Intermittent check engine light. When it was on threw a code for O2 sensor.

4) Partial throttle hesitation at 20 mph and above
5) Extended cranking time on restarts when engine is warm or semi warm, Engine will start after extended cranking time.
6) Decrease in fuel mileage, by a large amount


Dont really want to take it to a dealer, hoping to get some thoughts on here. I really dont believe it is plugs or wires or fuel filter.
Thank You

 

[98splorer]

2000 Xlt, 4.0 ohc Engine
1) On initial start after sitting all night, engine starts fine and idles fine.

2)Idle quality goes away after initial start when the engine is warm or partially warm. A) Low idle rpm=rough idle
B) Idle surges with a/c on
C) Rich fuel condition at idle " Bad smell at tailpipe
3) Intermittent check engine light. When it was on threw a code for O2 sensor.

4) Partial throttle hesitation at 20 mph and above
5) Extended cranking time on restarts when engine is warm or semi warm, Engine will start after extended cranking time.
6) Decrease in fuel mileage, by a large amount


Dont really want to take it to a dealer, hoping to get some thoughts on here. I really dont believe it is plugs or wires or fuel filter.
Thank You

The code should tell you which oxygen sensor it is. I would replace that.
A good scanner should tell you if there are any pending codes as well.

 

[gatzdon]

Here you go. I wrote up how to check the ECT Sensor.

http://www.explorerforum.com/forums/showthread.php?t=435965

You have OBDII, so this should be easy for you to troubleshoot.

 

[Codered]

will check ect sensor Thanks