Rough Idle Problem

[Jakeatkins]

I have a 2000 xlt with the 4.0 SOCH with 83k. Anytime the engine is cold when I start her up she starts revs up like normal and then almost stalls out and sometimes dies. She is idling at only 500-600rpm.

As well, this may be unrelated to the above problem, when I am sitting at a stop light she idles rough but only in pulses....rough....smooth....rough...etc. When this vibration occurs the tach barely moves.

I cleaned the MAS, new plugs, new wires, new air filter, new fuel filter, cleaned injectors, scanned for codes=none.
I am at a loss as to what may be cause both of these problems:confused
Any suggestions?

 

[ThePhoenix]

dont see mention of IAC....or maybe you need the gasket fix...

 

[Jakeatkins]

Gasket fix?

 

[BrooklynBay]

He's referring to the 00M12 TSB. Check # 51 in my list of useful threads for more information: http://www.explorerforum.com/forums/showthread.php?t=177975

 

[HUA99XLT]

I'll be willing to bet it's your intake gasket like the others have mentioned. I had the exact same problem on mine, replaced the gasket, ran like new again.

 

[Jakeatkins]

Correct me if I am wrong but if I had a manifold leak or vacuum leak then when I sprayed brake cleaner around the manifold and vacuum components the engine would rev up, right? I did this already and could not determine any leaks this way.

 

[BrooklynBay]

Have you checked the IAC as previously suggested?

 

[Jakeatkins]

No, I have not. I will look at the repair manual when I get home to find it. What am I looking for when I do?

 

[daffy]

Correct me if I am wrong but if I had a manifold leak or vacuum leak then when I sprayed brake cleaner around the manifold and vacuum components the engine would rev up, right? I did this already and could not determine any leaks this way.

Only when it's cold...after 2-3 minutes (sometimes less, depending on ambient temp), they seal themselves up.

When mine had bad seals, it would be running quite fine after 45 sec - 1 minute, even around 40 deg. F.

 

[BrooklynBay]

The IAC valve is located on the top of the intake. It should be cleaned with intake cleaner spray which is suitable for fuel injected vehicles. If cleaning it doesn't help, then replace it, and see if it helps the rough idle.

 

[aldive]

Take a look at this thread - http://www.explorerforum.com/forums/showthread.php?t=169335&highlight=quest

 

[ThePhoenix]

yeah, sorry...I am at work and not supposed to be on here much...so I couldnt elaborate

 

[Jakeatkins]

This rough idel thing is going to have to be on the back burner for now. Last night on my way home from work I went to pass a loafer on the highway and she studdered and wouldn't accelerate, them my check engine light began to flash. I check all guages as I pulled over and everything read normal, could see nothing obvious from under the hood and she continued to run as normal. This morning on my way to work she did the same thing, I work in a transmission shop so I am going to scan her this afternoon and see what the code says.

 

[Jakeatkins]

Checked and no codes I have no idea what the problem is. Maybe water in the fuel line?