I noticed right before my tranny went that my rpms wouldn't drop below 2k-2500 inbetween shifts when I first started the truck. It would sit and idle at normal rpms but once in motion when the engine was still cold the rpms wouldn't go below around 2500 causing rough shifts or I'd have to shift from 4500 up to the next gear to smooth out the shift. Is this an IAC problem?

 

Mine will run around 2-2500 when it's cold idling or in between shifts, it's very annoying.

 

mine does it as well, then one day it just wouldnt stop. So i took it to ford and it was the IAC. SO they fixed it, and it still idles high, and comes back ever now and then.

 

It seems like warmer days it doesn't do it as frequently but if it's less than 40F outside you can pretty much bet on it happening.

 

I'm sure somewhere in Fords electronics the IAC circuit is getting a signal that lets it know the temp. We, meaning Bob, should figure it out, and make a solution for it.

 

Sometimes mine does it.......usually slowing for a stop light or sign, push the clutch in, and it's still at 3000rpm until i fully stop. It's weird. I say it's a ford thing. lol. IAC definately.

 

Hmm.. havent had that happen ever..

Eesh, Im used to idling at 700 rpm.. I couldnt imagine 2500-3000..! I usually shift at 3000 or so, and having to force 4000 to shift properly woudl start getting a tad hellacious on our engines after a while.

 

mine does it when its cold it can be on 3000 and you can tap the gas a little and it goes back to normal ive replaced the iac many of times its just a 4.o thing i geuss every one i have ever drove does it

 

I'd think it's either a IAC, a small vaccum leak, or possibly a bad temp sender.

Rich

 

I would also check the following:

1) Throttle cable -- make sure it isn't binding some place

2) Throttle body -- make sure it isn't gummed up (internally)

3) Throttle plate return spring -- check to see if it is loose

 

Gotcha.

Thing is.....it runs perfect after about twenty minutes! I just hate to run it up to 4500 on every shift when the engine is cold like that until it stops.

 

One more suggestion.....have somebody press on the accelerator (gently, like you would driving it) while you are watching for the throttle plate to come back to the idle position. Do this while the engine is cold. If the throttle plate comes back to the idle position, then the problem is something else, like the IAC valve.......

 

First of all, without modifying the calibration, it is not possible to totally eliminate the RPM hang between shifts. It is there for emissions reasons.

On the other hand, the RPM could be higher than intended. Here are some likely causes for this:

1) IAC is sticking as mentioned above.

2) Closed throttle TPS voltage is out of range and not telling the PCM when it has transitioned from part throttle to idle mode. Allowable spec is 0.53~1.25v at closed throttle but a voltage near 1.0 is ideal.

3) A temp sensor is out of spec as mentioned above.

 

The throttle plate not returning fully to the idle position would throw the TPS voltage too high.....

 

Mine does the exact same thing a few times a week or so..

 

Dusting off an old thread.....mine does this only with the ac on. Push in clutch at 2500 rpms, stays there. Today it was 11 seconds, clutch in and in neutral. Started to slow down for stop sign, rpms started to fall. I can turn off the ac and everything returns to normal.

 

Most post dont say what they have but I know that this was an issue that turned into a TSB from Ford. My 04 would do the same thing till you almost came to a stop then come back down to standard base idle. Mine was intermitant and was never the same rpm when it did it. From 1500 to 2500 plus. Ford tried to tell me that it was factory that it did it. I aggree that it is in the PCM but not a 2500 rpm idle.

I think it was TSB 514. I have posted the same issues either on here of RPS (or both). Do a search and you'll find it.

Slightly higher than non moving or base rpm is ok. Higher than 1000 to 1200 and thats bad.

 

I ended up with CGN1 code in my computer. Sticker on the computer is wes1 I think.

for what thats worth

 

Try this TSB

TSB 05510 HIGH IDLE BETWEEN SHIFTS OR IN NEUTRAL - 4.0L ENGINE WITH MANUAL TRANSMISSION. (NHTSA ITEM NUMBER 10014693)

 

https://www.ranger-forums.com/f33/4-...metimes-74090/

here too

 

i aready had the pcm flashed and then replaced the pcm with new one replaced idle air no change