1990 Escort won't idle when cool...help please!!

Started noticing this at first sign of cool weather...car starts fine...idles at 1000 rpm...dies. If I hold the RPMs at 1500 it will drop to 1000 RPMs and surge back up to 1500 RPMs at what seems to be a regular interval...about once every 10 seconds...the problem continues while driving (if I stop at a stop sign I Have to put in neutral to keep it running). Once the engine is at normal operating temp...it goes away. :confused:

UPDATE...after the engine is warm...the idle still goes normal, then low...(still in a distinctive pattern). When it drops the check engine light comes on for a second or 2.

help please...do not want to get the wrong part... :confused:

i had this happen in my old car and the mechanic said it was the motor mounts were broken.

Have u checked spark plugs? Did you have the a/c on?? it could be the IAC valve.

Have u checked spark plugs? Did you have the a/c on?? it could be the IAC valve.

Don't think it's plugs...because as long as your foot is on the accelerator and engine is above 1500 RPM it runs smooth as it ever has...I think it is a fuel problem...
Is there a way to test IAC Valve? If I buy one do you think the parts store (like "AutoZone") would let me return it...we are almost broke...

Just remove the IAC valve and clean it with carb cleaner. Let it dry and reinstall. 5 minute job. Should cure the problem.

Just remove the IAC valve and clean it with carb cleaner. Let it dry and reinstall. 5 minute job. Should cure the problem.


Is it the thing right behind the injector with 4 screws, and when you take it off there is a spring...if not where is it?

Actually it is located on the throttle body. If you have a 1.8L engine it should be right on top. It looks like it takes 4 screws to remove it. If you have a 1.9 or 2.0 it will look like a small round cylinder with a wire connected to it. There may be two hoses connected to the top of the throttle body the valve is on the side opposite where the throttle cable connects. Remove it and clean it. You may want a new gasket as it may tear when you remove the valve.

Is it the thing right behind the injector with 4 screws, and when you take it off there is a spring...if not where is it?

please

Well...apparently this car does not have an IAC valve?!...I went to the parts store and looked at a repair manual...and this car has the single injector system and does not have the IAC valve...the guy at the parts store said my problem could be the "throttle position sensor"...
Any input would be appreciated!!

bump

Sorry for giving you wrong information but without knowing the size engine it is difficult to give proper info. The TPS could be your problem but it could also be the PCV valve blocked. The TPS is not hard to change, not sure of the cost. Have you changed the fuel filter lately?

there is no need to be sorry...I should have been more specific!
It is a 1.9L engine and has a single injector. I have looked for the PCV valve and cannot seem to find this either...(I know this sounds stupid) but I still can't find the little (expletive)!
The TPS is $26...

possible tp sensor

Tried the TP sensor...no help :crying: Still cannot find the PCV valve...

Actually it is located on the throttle body. If you have a 1.8L engine it should be right on top. It looks like it takes 4 screws to remove it. If you have a 1.9 or 2.0 it will look like a small round cylinder with a wire connected to it. There may be two hoses connected to the top of the throttle body the valve is on the side opposite where the throttle cable connects. Remove it and clean it. You may want a new gasket as it may tear when you remove the valve.

I have a 1999 2.0 escort that Idles like crap. I have wondered about the IAC but autozone wants almost 50.00 for a new one. Is there a way to check/test? I may try the removal like you suggested but do you have a pic or outline of this? I have the hanyes book is it in there?

if your rpms still surge from 500-1000...and you get a check engine lights..change out the O2 sensor on the car. 38.00 from Autozone and it takes a 7/8ths wrench to loosen it up(1/2 a turn will do that) and then unscrew it out by hand. I had to get the wrench up to the O2 from the bottom on an angle, but then unscrewed the sensor out from up top. Install is the opposite. The surge'n will clear it up and your gas mileage will improve.

Take care

if your rpms still surge from 500-1000...and you get a check engine lights..change out the O2 sensor on the car. 38.00 from Autozone and it takes a 7/8ths wrench to loosen it up(1/2 a turn will do that) and then unscrew it out by hand. I had to get the wrench up to the O2 from the bottom on an angle, but then unscrewed the sensor out from up top. Install is the opposite. The surge'n will clear it up and your gas mileage will improve.

Take care
no check engine light but I took the iac off and cleaned it with throttle body cleaner. Was a bit of carbon in it but wiped out what I could. Starts differnt now seems smoother but I havent gone anywhere yet.

New info!!!
While driving the car for an extended period...a couple more things that might help diagnose...

1. When engine is cold...no symptoms whatsoever...it will idle fine in park for about 10 minutes...then start the 1100 to 800 rpm drop then back to 1100...then back to 800...etc.
2. Drives fine while cold.
3. NEVER have the problem with transmission in drive and foot on brake.
4. While driving at steady speed no problem.
5. When coasting the check engine light comes on steady, and then, if I try to accelerate, the car will have no power. I have to put it in neutral
for a second or two...then the check engine light goes off and power returns.

Vacuum leak.....