4.0 idle problem

[Brandon12]

Car: 1991 ford explorer, 4x4, 4.0L, automatic
Problem: A good portion of the time I come to a stop my rpms bounce between 400 and 1000. Sometime it drops so low and dies and I have to restart. Sometimes its perfectly fine. Seem to be getting bad gas mileage also. Any ideas? Have to drive a ways Friday and don't want this problem then.

 

[fordfan86]

sounds like an o2 sensor issue. is the check engine light on?

 

[Brandon12]

The check engine light goes off and on at no peticular times.

 

[06RangerXLT]

Ever cleaned the IAC? I'd check for CEL codes, and see if you have any vaccum leaks. Is it only when you press the brakes, could have a torn booster diaphragm.

 

[Brandon12]

No never cleaned it, and it doesn't happen only when I use the brakes. Does the check engine light have to be to on for it to throw a code?

 

[fordfan86]

yeah im pretty sure it does but dont quote me

 

[4.0B2]

If the light has ever came on-- you'll have a code. Pull the codes.

If I had to guess, with past experiences of my motor, I'd say clean the MAF and IAC. Make sure to use mass air flow cleaner on the MAF not just brake cleaner or anything.

But your best is still pull the codes. I'm sure that there's a write up on how to do it in the tech library or if you're lucky like me you have the innova 3120 obd 1 and 2 code reader! Lol

 

[Brandon12]

What is the iac? And can I just pick up mass air flow sensor cleaner at schucks or napa?

 

[4.0B2]

yeah any parts place should have it.
the iac is the idle air control valve.

http://www.autozone.com/autozone/pa...rByKeyWord=idle+air+control&fromString=search

 

[Duane867]

Bad TPS ? ( throttle body position sensor )

 

[Brandon12]

Removed my mass aif flow sensor and it looks great so I put it back in. Also, I removed my iac and cleaned it out as best I could. Will drive it tomorrow and see how it runs.

 

[4.0B2]

so.................




did you pull the codes yet?

 

[Brandon12]

No. Probably this weekend. A friend of mine has a scanner

 

[4.0B2]

you can do it w/ a short piece of wire and watching the CEL flash

 

[Brandon12]

Scanner sounds easier haha but if my friend falls through I will ask you to explain.