IAC problem?

[NYC LS8]

For some reason, my '95 has developed what seems like an occassional vacuum leak. The car will idle fine, then all of a sudden, the idle will drop and come back up. It'll do this while driving, as well. When driving, it's more like something is cutting out and then comes back on. It is not transmission related, as it happens in park and idling. The car will start right back up, but the problem is getting worse and worse.

Car throws NO codes. Holds fuel pressure. Spraying carb cleaner on the vacuum hoses reveals no leaks - same for the "wiggle test" on the lines. Running the car with the EGR vacuum line plugged makes no change (EGR tube to exhaust leaks a little). Installed new cam position sensor just for laughs and that didn't help.

I had the IAC off on Saturday. The plunger inside didn't want to close (or go towards the middle of IAC) very easily. Could not find a replacement that day, so tried in vain to clean it (eventhough AllData says it cannot be cleaned). Didn't help. Ran the car with the IAC unplugged and it still would stall and sputter (maybe because the plunger was kind of open?).

Should the plunger inside the IAC snap towards the center if pushed down (towards the electrical connector)? Maybe the spring broke inside the unit? Would a bad IAC throw a code in these cars?

I looked on the Actron website for IAC codes, and the only ones that were close were these:

413
Idle Speed Control actuator
– operating at minimum limit.

414
Idle Speed Control actuator
– operating at maximum limit.

415
Idle Speed Control system
– minimum learning limit reached.

416
Idle Speed Control system
– maximum learning limit reached.

551
Idle Air Control (IAC)
solenoid – circuit failure.

I don't think the ISC system is it, and that IAC code is a problem in the wiring..I'm assuming.

What do you all think? I'm at my wits end with this car.. :Bang

 

[67Continental]

could be a CID sensor, my car does that as a result of throwing a CID code.

 

[NYC LS8]

That's the thing...I don't get any codes (except for the old O2 code that's since been cleared).

I think the IAC valve may have a shot spring inside where the motor is and I'm wondering if the partially opened valve is causing this, as it does it with the electrical connector unplugged, too.

If it is the problem, I'm dreading R&Ring the thing AGAIN.

 

[fordtechguru]

does it fast idle when cold?? or when running a self test koer... does it "hoot" occasionally...