Ok heres my problem and i need some serious help quick .
I have a 2000 F-250 super duty 4x4 long bed with the v-10 . So heres what happens , when i drive and i put it in neutral the rpm's shoot up to about 2 grand then drop down to a grand then slowly climb back up to about 2500 and then they just stay there until i slow down to somewhere under 5 mph . Doesnt matter how fast i am going , anything over about 5mph and if its in neutral (coasting) then the idle just holds at 2500 . I work at Big O and i have had the mechaincs here look at it and they cant figure it out , its not a vacuum leak or a intake leak . We are stumped and i dont have the cash to have for tear into it for hours to figure it out ... Any ideas ????

Thanks in Advance
Cory

 

I would disconnect the battery and then remove and clean the idle air bypass valve with a good spray solvent.

This would cost next to nothing and will probably help.

 

It's normal. The PCM won't allow it to idle down when the truck is moving. Don't worry about it.

 

There is no way this is normal . I am not talking about the truck mearly idiling i am talking about 3000 rpm here . It actually will sit and idle at 3 grand until the truck comes to a complete stop , there is no way this is normal . I tried cleaning the idle air bypass valve and no luck .

 

I would agree that's not normal. If you believe the idle valve is good, you might check the TPS next.

 

Yah i just ordered the idle air control valve . We think it was stuck open so i am gonna give that a shot and see if it helps . If not back to the drawing board !
Thanks for everyones help so far ... .

I ll keep it posted if it works or not ....

 

did you check for any codes on a scanner?
did you hook up a vacum gauge?

sounds, like a vacum leak to me

usually when the IAC craps out your truck stalls every time lift your foot of the pedal, but anything is possible I sapose

 

Ok so iac is new and same problem , i checked for codes and nothing . Didnt do a vacuum test yet , i guess thats next . I dont understand but man this is frustrating !

 

How long have you had the truck? Do you have a manual tranny?

Since new my truck will climb to around 2000 to 2200 RPMs if I kick it in neutral and let it coast. I have a '99 model.

When you come to a complete stop, does it go back down to about 950 RPMs?

 

Big Orn, maybe it's a way to keep someone from dumping the clutch and locking up the rear wheels?

 

Could be.

I don't know...could it be that the engineer was a redneck and wanted to keep the engine revved a little while deer hunting at midnight along a pig trail while in neutral with his billion candle power spotlight...

 

Sshhh.....

 

Well i bought the truck recently with about 92000 on it , engine looks great . Everything is in great condition for being lifted on 37's . I am slowly replacing little things that get worn faster because of the lift such as carrier bearing , tie rods , things like that . Little bit at a time . Now back to the problem . Recently i did a fi service on it at my shop and then a tranny drain and fill . Its a manual 5 speed . We used royal purple after the drain and fill (only fluid avail to me at the time ) . We did the fi service , now heres where the problem started , right after the fi service is when i noticed it . Now after replacing the IAC it does the same thing but the IAC from what i was told was bad anyway . It seems that anytime i am not at a complete stop the truck will want to idle around 2000 to 2500 . But its changed the last few days , now when i push the clutch in it will drop to normal idle of 950 -1000 but then it will slowly rise back up to 2 grand and hold until a stop . Tomm i am going to a ford shop to have a friends friend that does only super dutys look at it and i hope he has a answer ....

 

Yes...please keep us updated...


biz

 

I still think it's normal. The PCM is reading road speed while in neutral and not allowing the engine to idle. If there is a problem, then I've had it for years.

I have never heard of this except on manual trannys...

Yes, do keep us updated; I'm curious now...