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Discussion Starter · #1 · (Edited)
First off , does a 2002 Focus ZX3 manual trip a code if IAC is acting up ? Some cars do I was told but not sure about my car because it started weird again , after not doing this for almost a year.
It started really rough as if flooded , almost stalling , then finally smoothed out , BUT the idle stayed high like 1200-1500 RPM for many miles and it was surging while at light-throttle cruise. It was like this for like 8 miles , then I shut it off and when it restarted after a while , like 30 minutes , it ran normal ! What gives ??? NO CODES , EVER !
Last year I had bought a new Ford IAC but was talked out of installing it by a LONG TIME mechanic , who told me if it was the IAC , there would be a code. I am not buying this. I sent it back for full refund. Some more sophisticated later model cars probably do set IAC codes. Doubt mine does. FROM GOOGLE
one of the most common symptoms associated with a problematic idle air control valve (IAC) is, irregular idle speed. Because, the (IAC); is programmed to regulate and maintain the engine idle speed, at a constant rate. If the valve fails or has any issues, it can cause the idle speed to be thrown off. This may result in an unusually high or low idle speed; or in some cases, a surging idle speed, that repeatedly climbs and falls.
When this happened last year I ran PEA fuel cleaner for several tanks , it went away , of was just coincidence. ?
There is no 0505 code or any other code. 202k miles , uses very little oil in 5k miles.
Does it or the ports it connects to just need cleaning ? Here is a screenshot from a YouTube video.
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Discussion Starter · #17 ·
After reading other people with IAC issues I believe it is the case with mine. The fact it acts flooded when cold sometimes and tries to die points to the IAC not letting in air when cold-started.
Then , after that it acts like the throttle is hanging open , so if it is sticking open when warm it is essentially causing same symptoms as a vacuum leak (high idle speed). I have no idea why there is no IAC code , but some things require the same thing to happen a few times before it will set a code.
What is funny is I remember my dad keeping the choke plate from closing with a clothes pin on our 65 Impala wagon 4bbl Quadrajet carb when it was below freezing in Mammoth to get the car started back around 1974. 😂
 

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guy in the videos always says " looks the same as the Ford part , works the same" No it doesn't ! He isn't fooling me.
Today I replaced my IAC again. That makes twice in 30 days.

First one was a WVE from Rockauto. It worked fine except for a 2 second starting flare up to 3,000 RPM. It has a screw near the power connector, a 1/8" square drive head in plain sight. Must have some purpose. I suspect it controls starting flare up RPMs, so the same IAC can be used on bigger motors which need more air.

For backup, I bought an Ebay clone IAC for $30, and installed it today. Starting RPMs peaked around 1,500 or so, as expected. Went for a highway drive and then back to town. A-OK until the first red light. Then the motor stalled. Oops. Next intersection, stalled again. I had to use neutral and foot on the gas to keep it running. Went home for lunch.

After lunch I took a longer test drive, both town and highway. Problem vanished. No more stalling. Must have been some weird ECU relearning glitch before lunch. If that was a one off, I'll leave the Ebay clone on the car and keep the WVE for backup. Hate doing that job a third time. Twice was enough.
 
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