rough idle first start up

[exploder10]

i'm some needing some help plz. I've bought another explorer this time a 99 xlt with 321k miles. First thang in the morning b4 motor warms up it idles really rough and actually during sometimes.after it warms runs like s brand new problems. Sometimes it does have a lil vibration through gas pedal (if even related). Plus when sitting at a red light n mornings seems like it surges I guess u would say then if you have to sit to long it dies.

 

[J_C]

This may not help much but at 321K I'd consider it a parts vehicle. Otherwise you're probably going to end up putting twice as much into it as it's worth when you're finished.

Any trouble codes set? Can you get any info from prior owner about services done in the past few thousands of miles? Was it daily driven or sitting around with very old gas in it? Have you done anything to it yet like check spark plugs, dump some fuel injector cleaner in, replace fuel filter? You might try cleaning the IAC too.

I'm just starting with the cheaper/quicker/easier stuff that may be due to be done even if they aren't the most significant problem.

 

[Gadget X]

X2 on cleaning the Iac valve!

 

[exploder10]

Don't know the guy all I do know is that they had it sine 36k. It was just passed down to kids and last kid drove it about an hr to school. I havent really checked anythang as far as plugs or ne thang. All that I have done so far is clean map and changed ect off of my other explorer with a bad trans and dumb some seafoam into the tank.

 

[J_C]

It's hard to say because at that many miles... maybe it's had gaskets changed or maybe not. Maybe its had a whole engine rebuild or swap, or transmission, or who knows what.

If doing the quick easy cheap things doesn't help you might take it to a trusted mechanic.

 

[angstrom08]

I bought an 01 explorer with 200k miles a year and a half ago. Cleaning the IAC valve improved things considerably. However, it was also necessary for me to clean the throttle body.

At first, I didn't think cleaning the throttle body would have any practical significance. However, there's a little hole in the butterfly valve that had clogged from all the soot and oil combination that gets recirculated. This, as I understand things, allows a minimum amount of air through even when the throttle butterfly valve is otherwise closed. The IAC is used to adjust the incoming air volume in addition to the throttle.

Sorry for the bad focus, but here's a photo of mine before I cleaned it.

For what it's worth, I'd recommend getting one of the cheap elm327 bluetooth obd scanners from amazon.com. They're around $20 and helpful for getting codes, reading sensors (using car gauge pro), etc.

P.S. This is my first post to explorerforum. Been reading posts for a few months now and have appreciated the wisdom. This is me trying to return the favor, but I am by no means an expert.