Very High Idle Problem

[MustangLX-5.0]

opps...The computer desk got knocked over (somehow) and trashed the monitor.So after a new monitor,I now realize you have your problem fixed.Good to know that IAC was the only thing at fault.Now you see what I mean about Autozone crap.

Just adjust the idle screw clockwise until it just starts to touch the linkage.Around 700 - 750 RPM is a good set idle.It's also good to keep it at that setting so the A/C compressor doesn't keep kicking off at idle due to bogging down the motor.There's a switch in the compressor that will disengage clutch when WOT or when Idle falls too low.

Also,about the MAF.I typically find that when the engine is cold,unplugging the MAF at idle will usually result in eratic idle and/or stalling.After running for several minutes,unplugging the MAF causes some slight shifting in idle speed,more like a sudden drop and running a little rough but tends to clear after a minute or so.Just from experience on multiple vehicles.The MAF adjust engine functions while constantly reading ambient air pressure and temperature.

As for the campshaft sensor fault.It might've been with the faulty wiring you had back when you thought your coil pack was crapping out.The wiring for that is in the same harness.

Now go change your oil...................that constant 3k rpm is cooking the oil.Maybe change it then after a week or so change it again just to flush some of that crap out.

 

[chrispy98cobra]

i know this post is kinda old, but i am having the same problem with my cobra, but it idles at 2k rpm instead of 3k....here is what i found after replacing the TPS and the IAC...i started the car and it was idling at around 1800. then i unplugged the IAC and it dropped to around 900 which is normal...i was revving it and holding it steady and the idle would return to normal every time......then i unplugged the maf with the IAC still unplugged and it didnt die...when i plugged the maf back in it was still fine until i plugged the IAC back in....as soon as i did that the idle shot up to 2k again and stayed there, so what does all this mean?

 

[jonjonjonjon]

I'm not sure if your problem is fixed or not, but it sounds like its your idle air controller. That ended up being the problem in my case. Even though you bought a new one, it seems to be that the quality of it may vary depending on where you buy it. I think the other guy in this thread had a problem with his first one, but then bought one from NAPA and it fixed the problem. Maybe you should try getting a quality one from a store, and if it doesn't solve the problem just neatly take it back.

 

[jonjonjonjon]

Just thought I'd put in a quick update. My problem was resovled with carb cleaner for quite a while now, but I just started having the same problem a few days ago. I bought an IAC from autozone, because it was significantly cheaper than anyone else. It did not help at all, and I think it actually goes to a 4.6L motor (which may be why it didn't work for ground fault either). I was going to buy the one from NAPA, but they have a no return policy. So I went to Murray's and had them look up the part. The had to special order it, but it is an exact OEM part, it even has the Ford logo on it. It fixed my problem and works perfect. Plus they matched Autozone's price (took $30 off). So if anyone is having this high idle problem and needs a new IAC (i.e. if your problem isn't related to your TPS or MAF) I would highly recommend buying a replacement from Murrays.