YACT: HELP my POS Ford wont Idle Right!

[CrackRabbit]

94 Ford Escort 1.9 ltr 126000 miles

For the past several days the car will idle up to redline when started, but only if the Idle Air Control (IAC) valve is plugged in. If i unplug it it idles fine but i get a nasty check engine light. I have replaced the IAC and the new one does the same thing as the old. Any sugestions? The transmission is about shot on this thing, and if i cant get it to idle right im not going to bother getting the transmission repaired and will attempt to trade it in and get a couple hundred for it....
Stoopid Phord....

Thanks
CrackRabbit

 

[Pepsi90919]

could be an electrical problem.

 

[Ornery]

Throttle Position Sensor?

Mass Air Flow (MAF) Sensor?

 

[CrackRabbit]

replaced both... stil the same

 

[Ornery]

Fuel Pressure Regulator?

Is the throttle plate seating right?

 

[CrackRabbit]

i havent tried the fuel pressure regulator, but im not seeing how that would affect it if it doenst do it with the IAC is unplugged

 

[Ornery]

The whole thing doesn't make sense. Only the cruise control can grab hold of the throttle and open it up to redline, AFAIK.

 

[CrackRabbit]

the car does have cruise control.... does that affect the IAC in any way?

 

[Xionide]

It could be because its an escort not a ford.

-Xionide

 

[Ornery]

Nope, it shouldn't, but what else can redline the engine? If the fuel injectors pour a bunch of gas in, but the throttle plate is nearly closed, it will just flood. See what the throttle plate is doing when it redlines.

 

[CrackRabbit]

Too dark tonight, but i will check it tomorrow. but i'm pretty sure that its closed, it was working fine when i installed the new TPS, and i gave it a good cleaning while i was at it.
BTW, thanks for the help Ornery.

 

[thedarkwolf]

Try checking the codes before thowing more money at it.

 

[Pepsi90919]

Originally posted by: thedarkwolf
Try checking the codes before thowing more money at it.

it's because he unplugged the IAC.

something is sending too much voltage to the IAC making it open all the way.

 

[CrackRabbit]

think maybe the ECM is toast?

 

[Pepsi90919]

it's likely. if you could get a DMM and see what's coming out of the connector to the IAC...


of course you need something to compare it to.

 

[Quixfire]

Originally posted by: CrackRabbit
think maybe the ECM is toast?

It very well could be that. If the PCM thinks the engine is stalling it would open the IAC valve until it stopped trying to compensate.

You should have a code in the PCM for idle control.

 

[CrackRabbit]

Ive had the codes scanned before and all that came up was the TPS being out of range because it was idling so high without the throttle being pressed. And the MIL is on now because i have the IAC unplugged. No other codes present.

 

[Jzero]

Originally posted by: Xionide
It could be because its an escort not a ford.

-Xionide

Yes. After careful research and inspection, I have located the problem:

94 Ford Escort

Dumping my '94 Escort was one of the best decisions I ever made. It's so nice to go start my car and not actually wonder if it will actually start or not.

Someone else on here had the exact same trouble as me with a '94 Escort that he had.

 

[CrackRabbit]

It could of been worse, i could of kept the 93 Tempo i had... *shiver*

 

[Thegonagle]

Originally posted by: Quixfire

Originally posted by: CrackRabbit
think maybe the ECM is toast?

It very well could be that. If the PCM thinks the engine is stalling it would open the IAC valve until it stopped trying to compensate.

You should have a code in the PCM for idle control.

More likely, IMO, is that a transistor somewhere in the circuit that controls the IAC has short circuited. This could cause the computer, unknowingly, to send constant full voltage to the IAC.

 

[Quixfire]

Originally posted by: Thegonagle

Originally posted by: Quixfire

Originally posted by: CrackRabbit
think maybe the ECM is toast?

It very well could be that. If the PCM thinks the engine is stalling it would open the IAC valve until it stopped trying to compensate.

You should have a code in the PCM for idle control.

More likely, IMO, is that a transistor somewhere in the circuit that controls the IAC has short circuited. This could cause the computer, unknowingly, to send constant full voltage to the IAC.

If that was the case then the PCM would have stored a code for the circuit to be either shorted to gound or open.