If blipping the throttle brings the idle down then that tells me there is something sticking in the area of your throttle. The throttle blades control the hard idle, the IAC controls the computer idle speed and the TPS tells the computer to enrichen the fuel because you have pressed on the throttle.

 

Ed i figured out what dash pot was. (A device that prevents the throttle from closing too quickly. Prevents the engine from stalling during quick stops.) I guess I am just used to it.
Terpford, I have checked the throttle blades by hand, unplug all the sensors one by one and they seem to be ok. It stuck on my friend twice why he was driving it because he keeped free reving the motor because he liked the exhaust note.(I told him to stop it) So it does it at cold startup 98%/hot startup 70% and when you free rev it to long(showing off). My next step is to check all the grounds. I forgot to hook the ground to intake one time and battery light wound come on and half the gauge lights wound not work. Who wound of thought 1 ground wire wound do that? I not good at electric problems.

 

Yeah, it's probably a device used on carb'd engines. but it's a term used by the author in the Ford EEC IV book that I have. I guess the IAC is the dash pot device for our engines.

Here is what I do to keep the idle down:
-Before cranking the motor, give the gas pedal a quick jab. Frees up the TB plates.

-Start the motor and then goose the throttle after a few seconds of the engine running. Sometimes the idle drops, and if it doesn't, I repeat the procedure as if starting it for the first time.

-When the engine seems to run at lower idle, I drive away. Can't say what the RPM is since my RPM gauge is wacked!

There are times when I don't need to do this, but most of the time it does. This high idle problem hasn't gone away, even after cleaning the TB and throttle plates/blades. I've even replaced both the TPS and IAC valve, albeit with non-OEM parts.

 

when i first git in truck i stab gas then start. it idles fine. then when i put in gear. ( 5spd) itll go up.. like when i shift i put clutch in it revs high, let out clutch itll kinda bog 2nd to 3rd.... but whenever it high idles i jus flick the gas n itll go away.. normal? what to fix it n how much is each part?

 

farmereinar,

Did you ever get this fixed 6 years ago? I have a 94 with 97,000 original miles on it doing the same thing. The idle jumps the second the ABS light comes on and sometimes it lasts for a minute or 2, other times for 10-15 minutes. I too have changed everything out, It throws no codes and 2 shops cannot figure it out. The ABS light is REALLY a strange part of it.......

 

I used to have the same problem. after replace everything i replace the fuel pressure regulator. Be sure to blow air from the return line back to the tank to clear any possible clogging or restrictions.1000 miles and counting after that nightmare.

 

Yes I know this is an old thread.

A dashpot was used on carburetors engines.

This “procedure” means to me that the throttle body shaft is worn causing the blades to bind in their bores.

Lococuban, I’m not sure how the regulator would have fixed the problem. Did you check the system for codes before throwing parts at the problem?