My 04 ranger i recently bought has a high idle at times. When i start it , it comes up to about 1500 RPM. then slowly comes down to 6-700. But then when i am driving it the RPMS come back up. Like when i come to a stop sign and push in the clutch the RPMs are back up to 1500 or so.

The throttle linkage is free and does not stick. I cleaned the throttle body and IAC w carb cleaner but that made no difference. There is no current check engine codes. Any ideas?

 

My B3000 drove me absolutely insane with this issue. I took the IAC valve off a few times and cleaned it. There is a little filter/breather on there too that you need to get at. If memory serves me right, there is a plastic cap which comes off which allows access to the breather. It's only a temporary fix though and the problem will come back. Try Googling this issue as well; you'll find additional information.

 

the wonderful world of computerized automated electronically controlled cars that are a royal pain in the neck to troubleshoot and arent running right and are supposed to be easy and trigger a check engine light but not always do. i like putting around in my little truck but not as much as i love my 69, that thing is always running nice and smooth.

 

Well i bit the bullet and ordered a IAC valve. It is $86!! I hope this fixes the problem

 

I would also check for vacuum leaks. That can and will cause high idle problems.

 

If the IAC doesn't fix it & if the PCV valve hasn't been checked/replaced & is sticking, or not sealng well, it can cause an uncalculated for vacuum leak that'll mess with idle speed, so maybe consider adding it to your suspect list.

Let us know what you find.

 

this is a royal pain and happens to me sometimes while i am downshifting and am trying to rely on just engine brake to slow me down, yet its acting like a cruise control and doing its own thing, sometimes accelerating on its own. like a toyota!

 

When mine began to act out like this, it was the IAC & cleaning it didn't last, but was a good trouble shooting step.

Finally replaced that puppy two about two years ago to fix the problem.

Now this past summer the replacement IAC has begun to act out the same way, but it wasn't an OEM part.

 

truck does not have a PCV

 

It likely has one, unless you or someone else has removed it, or your having problems finding it on the shoc 4.0L.

Look toward the center rear of the engine on the intake manafold, about two inches in from the firewall, for two hoses going into a "T" connection atop the PCV valve.

If you have 100k miles or more on it, it's time for a change.

 

bad pcv valve will cause a high idle and not throw a code.

 

Well I tried the PCV and the One i removed from the valve cover didn't even have a check valve. It was just a fitting to go to a hose to go to the intake hose. The one i got from NAPA has a check valve but the plastic tube now cant snap on, it has a different nipple. So i had to use a hose and clamps.

That did absolutly nothing.

I put the IAC on and it fixed the problem

 

Good feedback on your repairs & to hear you seem to have things put right.

If the innards of the old PCV valve were gone, it needed to be replaced, as the old one was causing an uncalculated for vacuum leak & that'll mess with fuel trim & the IAC's ability to control idle speed.

If you didn't pull the battery B- cable to wipe the computers memory while you were doing the repairs, you'll likely want to consider doing it, so the computer can begin to build new fuel trim tables & learn new cold & warm idle strategy with the new parts in place & maybe prevent some driveability problems.

This repair should help the mpg too.

Some more thoughts for consideration.

 

There was nothing in that part i replaced "pCV" it was just a nipple

 

I lied. My high idle prob is still there. I replaced the PCV, TPS, IAC and checked for vaccume leaks and found nothing. Driving down the road if you push in the clutch the RPMs will drop to,2k and stay there with my foot off the gas. Will stay there for at least 30 sec.

Any more ideas