Erratic / Jumping idle

[resq302]

My wifes 2008 Eddie Bauer Explorer V-6 recently started having an erratic idle and we've started noticing it while at higher RPM's. Its almost as if there is a cylinder that misfires but no engine light is coming on. The car stumbles like it is going to start to die, then the idle jumps up and smooths out. A little while later it does the same thing. The car has I think 74,000 miles on it and has never had the plugs or wires changed. I change out the fuel filter roughly every 24,000 miles and did it recently in the spring.

Any places where I should start looking? Could a misfire not trigger the check engine light?

 

[Rcflyer330]

http://www.explorerforum.com/forums/showthread.php?t=412844

Look at the post I made in this thread I listed the causes of rough idle. Note these are taken from the Haynes repair manual and are not all of the possible causes but Is a good list to start with. I would start with number 1 vacuum leaks.

 

[Bobmbx]

My wifes 2008 Eddie Bauer Explorer V-6 recently started having an erratic idle and we've started noticing it while at higher RPM's. Its almost as if there is a cylinder that misfires but no engine light is coming on. The car stumbles like it is going to start to die, then the idle jumps up and smooths out. A little while later it does the same thing. The car has I think 74,000 miles on it and has never had the plugs or wires changed. I change out the fuel filter roughly every 24,000 miles and did it recently in the spring.

Any places where I should start looking? Could a misfire not trigger the check engine light?

Mine is doing the same thing. I'm not convinced its the engine yet. I also suspect it may be the TC trying to lock, because I have other issues with it while driving. It feels similar, when starting up an incline and putting pressure on the throttle, it feels like the tranny tries to shift, fails, and tries again. This causes a fairly significant "stumble".

Getting off the throttle then coming back on "cures" that, until the next slight application of power.

 

[Bobmbx]

I cured my issue by replacing the spark plug wires. You can barely notice that the engine is running.