Hanging High Idle

[Dragcity]

I have noticed my idle seems to be hanging. What I mean is this:

Engine at normal operating temp
In drive, say, at a stop light
As I stop, and the car slows, RPMs go down
Stopped, idle hangs at about 1,000 Rs
Then, 4 seconds later, falls to 700...?

If I 'blip' the throttle, the RPMs go up and hang at 1,000, then 4 sec later fall to 700.

I have my tune set to idle at 650 in both Neutral and drive.

Is this a sign the TPS is bad?

I have cleaned the MAF and Throttle Body two times. The throttle plate does not stick, nor does the accelerator linkage.

Hit Me fellas!

[Zack]

Sounds like the IAC needs a shot of carb/choke cleaner.

[magindat]

Sounds like the IAC needs a shot of carb/choke cleaner.

Yep. Take it off. 2 bolts, 1 harness. Clean and replace.

[Dragcity]

will do guys, Thanks for the assistance.

[CBT]

Yep. Take it off. 2 bolts, 1 harness. Clean and replace.
At the risk of sounding stupid(er), do you have a picture of the part?

[Dragcity]

At the inlet of the plenum (end of the black corrigated tube) there are two electrically connected sensors. One black = TPS (Trottle Positioning Sensor) and one silver = IAC (Intalke Air Controller) Each have two attaching screws. The TPS has phillips head screws and the IAC has 8mm hex head.

I took the entire throttle body off and removed the IAC and cleaned all components with appropriate cleaner. Put all back toghether, reflashed EEC, disconnected Batery for 10 min. I will report after my ride into work in the AM.

I did run it prior to re-flash and disconnect, had same issues. Hope I have better results morrow.

[TooManyFords]

That is a normal feature of the dashpot functions of the PCM. You can programmatically remove that delay or at least lessen the time. It does NOT require taking anything apart.

Sheesh! Everyone jumps on the IAC for everything these days!

LOL

john

[DEFYANT]

Here is what the IAC looks like:

http://i5.photobucket.com/albums/y193/Defyant/IAC.png

[TooManyFords]

Repeat after me,

It's NOT the IAC...
It's NOT the IAC...
It's NOT the IAC...


John

[CRUZTAKER]

That is a normal feature of the dashpot functions of the PCM. You can programmatically remove that delay or at least lessen the time. It does NOT require taking anything apart.

Sheesh! Everyone jumps on the IAC for everything these days!

LOL

john

Thank god YOU said it.

I was weary responding earlier, not being a mechanic...but mine has always done that. Since day one with 200 miles.

My first notion to respond was..."Normal."

[CRUZTAKER]

Here is what the IAC looks like:

http://i5.photobucket.com/albums/y193/Defyant/IAC.png

Only if connected to one of those Koll-Aid mixers.:P

[DEFYANT]

Repeat after me,

It's NOT the IAC...
It's NOT the IAC...
It's NOT the IAC...


John


I didn't say it was, someone else was asking what the thing looked like.

[RCSignals]

Thank god YOU said it.

I was weary responding earlier, not being a mechanic...but mine has always done that. Since day one with 200 miles.

My first notion to respond was..."Normal."

Somewhere around here there is a post by Jerry W that talks about the delay in throttle response in Fords.

[DEFYANT]

That is a normal feature of the dashpot functions of the PCM. You can programmatically remove that delay or at least lessen the time. It does NOT require taking anything apart.

Sheesh! Everyone jumps on the IAC for everything these days!

LOL

john


Somewhere around here there is a post by Jerry W that talks about the delay in throttle response in Fords.

Since this is normal - I never noticed until now that you mentioned it, why does it do this? Whats with the delay?

[TooManyFords]

It is the function that keeps your engine from stalling when coming to a sudden stop and keeps the brake booster charged. This is referred to in the tuning as the "Dashpot" feature and it is tunable.

John

[Dragcity]

My ride to work today was with a strong, steady running Marauder. It liked the cleaning, re-flash and re-learn.

Same issue though. Funny, my Marauder just started doing this, about 500 miles ago. I have several tunes i will try over the next several days. I can say that nothing in the throttle body is dirty. I even filed off any large casting marks inside and out.

Maybe I can replace the TPS (although the top phillips screw wont come out)

The IAC was dirty in there, but not any more... Eh, who knows, who really frigggin' cares? Car still runs well, just doing something new for me, that it hasn't done before.

Anyone know if the throttle plates are supposed to close all the way, or are they supposed stop (with the adjuster) with a bit of a pitch open? I suspect this is something I should NOT Fuss with.

I like low idles and can't get it under about750 Rs with my tune. Again, what is odd in all this is, I was able to keep my idle at 600 without the said hanging idle.

Just another one of the magical wonders of electronically controlled mechanical operations.

[ckadiddle]

Uhhh..at the risk of looking like an idiot.....if your MM is not s/c, have you tried swapping back to the factory stock tune to see if it still does the same thing?

[Dragcity]

I wish I was Blown.....

I did try the stock tune whan this first came up for me. No better.

It really isn't a big deal, I guess. I'm just being fussy.

[ckadiddle]

I wish I was Blown.....

I did try the stock tune whan this first came up for me. No better.

It really isn't a big deal, I guess. I'm just being fussy.
Nope, mine doesnt do that. Something is wierd with your car. I don't think you are beng fussy. You just want it right.

[magindat]

Nope, mine doesnt do that. Something is wierd with your car. I don't think you are beng fussy. You just want it right.

Mine either.

John, right again, except he said this is NEW behavior, so something had to have changed. Jus' tryin to help a brother out. Also said he changed tunes with same result of new behavior. Something physical changed.

Drag, I'd also look around and esp under the TB (although I know you took it off) for loose/cracked/leaking vac lines.

Good luck.

[Dragcity]

I think I need to beat the **** out of it for a while. Haven't done that in a long time. Haven't seen 100 in a year.... Used to do it daily.

[rayjay]

Mine was like that when I installed the Accufab TB last year. It eventually settled down.

[Marauderjack]

Hey Joe.....

I'll bet with the A/C running more with warmer weather it is simply holding the idle up a bit.....Also, whenever I "Reset" the EEC as you have done it takes several days for the idle to settle in!!:cool:

Marauderjack:burnout:

[Dragcity]

Just wanted to re-visit this thread I started several weeks ago.

Seems everything is all straightened out now ???? 90 degrees, air on, idle at 650 RPM at a light. Touch the throttle and no hang ups???? Been in good shape like this for a few weeks now.

Could this be an Ethenol issue??? The ECU learning how to deal with it????

At any rate, all is well with the world, and my idle does what is expected...


FABULOUS !!!

[OneBADLsE]

Just wanted to re-visit this thread I started several weeks ago.

Seems everything is all straightened out now ???? 90 degrees, air on, idle at 650 RPM at a light. Touch the throttle and no hang ups???? Been in good shape like this for a few weeks now.

Could this be an Ethenol issue??? The ECU learning how to deal with it????

At any rate, all is well with the world, and my idle does what is expected...



FABULOUS !!!



For the record, every lincoln/merc/crown that i have been in does the same thing you describe in this very thread. It is a normal thing. Beating the piss out of the car does make it run better though...I started a thread about that a week or two ago. ;) The ECU is a strange and mysterious program. I noticed it can get moody at times.