rough idle

[feloniousQ]

I have a '01 SR5 4wd with 88k miles. Lately I have noticed that after cranking the truck and letting it warm up, that the RPMs intermittently drop (down to around 500rpm or below) when it is in gear and at idle speed. This is causing some engine shake when stopped at a red light or in traffic, etc.

Anybody have any ideas why the RPMs would start consistently dropping like that? I have had the truck since 33k miles and have not changed the plugs or wires. However, there is no associated spark knock or loss of power or any other reason for the plugs to be suspect.

Anyone have any suggestions on how to figure out what the problem is?? Anyone else had any similar problems?

Thanks

 

[alotawatts]

Only guessing...vacuum leak ? check all of the small rubber hoses. IAC intake air control valve ?

 

[greasefingers]

What are you waiting for? The truck needs a tune-up before trying to diagnose any further. And I am sure that your MAP sensor is dirty as well.

 

[mikes4runner]

What are you waiting for? The truck needs a tune-up before trying to diagnose any further. And I am sure that your MAP sensor is dirty as well.

I think you mean the MAF(Mass airflow sensor).

oh yes 88K and this has never been cleaned is most likley your problem.

Try cleaning the MAF first cheap and easy to do.



Mike

 

[feloniousQ]

mass air flow sensor and O2 sensor replaced about 4 months ago.

i plan on running some fuel injector cleaner (done), recharging my K&N (done today), and changing the plugs and see how that helps

 

[mikes4runner]

mass air flow sensor and O2 sensor replaced about 4 months ago.

i plan on running some fuel injector cleaner (done), recharging my K&N (done today), and changing the plugs and see how that helps

Is the K&N filter lubed with oil if so try cleaning the MAF. they can get dirty quick.

Mike

 

[greasefingers]

Oops sorry about that, my Jeep has a MAP sensor and the T4R has a MAF sensor.

It would be more efficient to receive all pertinent information in the first post. Leaving out the fact that a new MAF & O2 sensor was installed, only leads us to guessing instead of more effective trouble shooting

 

[feloniousQ]

update

Just to update the situation - I got some time to get into the engine, and the throttle body was completely gunked up. Cleaning it out with some engine cleaner and a toothbrush completely resolved the idling issue. I also changed the plugs for good measure and she purrs like a kitten