Very high idle problem!!

[NitroRCfan]

My 2000 Ranger 2.5 4-cyl has suddenly developed a very high idle issue. It idles so high i cant even drive it for fear of tearing up the clutch or even doing damge to the engine from it revving so high on these cold mornings. I dont have a tach but to give you an idea, going down the road in 5th gear it will run 70 mph by itself. So far I have no check engine light. I have taken the throttle body off and cleaned it thoroughly and replaced the throttle position sensor. The guy at the parts store said it could be the, I think he called it a throttle control motor or something like that, could be the problem. It is located on the throttle body also. Anybody got any thoughts on this?

Thanks!

 

[rwenzing]

It sounds like your Idle Air Control valve is stuck open. There is no "throttle control motor" on your truck.

 

[NitroRCfan]

Just for the heck of it I unplugged the IAC and fired it up and it made absolutely no difference. Dont know if that means anything or not. Thanks!

 

[rwenzing]

Just for the heck of it I unplugged the IAC and fired it up and it made absolutely no difference. Dont know if that means anything or not. Thanks!

I was thinking that it was physically sticking, not being held open by a PCM command. There is a close tolerance piston inside and it can get hung up with dirt or varnish. You could try tapping the outside of the IAC to see if the idle will change. Some people have had temporary success by removing the IAC and cleaning the piston with contact cleaner. That would at least be good for diagnosis of the problem. Often, a permanent fix requires replacement of the IAC.

 

[NitroRCfan]

I started it up so I could see what the throttlebody is doing and it is completely closed. Common sense tells me that it has to be the IAC. I just checked on a new IAC and its $110. Ouch! Should I just bite the bullet and take a chance that it is the problem or just take it someplace?

 

[rwenzing]

I would try cleaning it. It might fix it permanently but even if it doesn't, you will know if it's the problem. Being sure would make it easier to spend the $110 IMO. Also, I would shop that price a little. There can often be quite a difference in parts prices from dealer to dealer.

 

[NitroRCfan]

I actually let it soak in cleaner overnight and it didnt help. $110 was the cheapest I found for a Motorcraft part. Ford wanted $140!!

 

[nova801428]

parts america is cheaper aka shucks, I got mine for an 86 for $55 I think, it will solve your problem

 

[rwenzing]

I actually let it soak in cleaner overnight and it didnt help. $110 was the cheapest I found for a Motorcraft part. Ford wanted $140!!

When you had the IAC off, did the piston look like it was stuck open? If not, here's another thought. Check for vacuum leaks. Just pulling a hose off the intake manifold can make the RPM's rise too.

 

[aldive]

Also, how is the thermostat?

 

[NitroRCfan]

Thanks for all of the help guys! I found a new IAC at Advance for $50. Problem solved!!!! Thanks again for all your input on this!

 

[FoMoCo_RANGER]

Thanks for all of the help guys! I found a new IAC at Advance for $50. Problem solved!!!! Thanks again for all your input on this!

good to see you got it fixed, my next suggestion was gonna be unplug your MAF, and see if it slowed it down... i had that same issue on my 2001 the first day i had it, it would idle at about 2500 RPM.... i unplugged the MAF, and cleaned the contacts, and BAM!!!!!! problem fixed

 

[nova801428]

told you

 

[NitroRCfan]

Yep Nova! After reading your reply I decided to give it a try. You da man!!! LOL

 

[nova801428]

not at fixing my truck though:thumbdwn: