do I need a new IAC?

[Sonicpony]

my 01 GT has 46K miles and it was idleing high for a few days(around 1100rpm) and then the MIL came on w/ a P1506 Idle Air Control Over Speed Error.
I cleaned the IAC w/ carb cleaner and checked for leaks on the intake and didnt see any. I started the car and it seemed to be still idling a little high but I'm gonna drive it tommorrow and see if its better after it cools down completly. Does the black box have anything to do w/ this? could it be clogged or ??

 

[DTNODYA]

Check the gasket for the IAC ... I know you said you checked for leaks ... How did you do this? With carb spray or just visual inspection. I'd check that crappy ass gasket that goes btw IAC and plentum. Try WD-40 in the IAC (someone chime in to correct me if I'm wrong) ... I have read that it can be a "temporary/ghetto fix" until you can get a new IAC (if that's even your problem, which it probably is). Hope that makes sense.

 

[Mike97gt]

try cleaning it and check the gasket first, but most likely you will need a iac valve

 

[Pennywise2]

I had the same exact problem as you.My idle was very bad.
Instead of trying to clean it I just got a new Motorcraft IAC
valve and installed it and the problem went away.

 

[tomustang]

I tink it should be mandatory that ford should give away a box of IAC for each mustang sold

 

[Sonicpony]

update, I just spent $100 on a brand new Motorcraft IAC and installed it today. The gasket was in perfect shape. I drove around after and its acting exactly the same, the rpm's are dropping very slowly and when I come to a stop it idle's @ 1100-1200 rpm's.( with O/R x and SLP's its vey noticeable) haha,? im confused

 

[RandyStinchcomb]

update, I just spent $100 on a brand new Motorcraft IAC and installed it today. The gasket was in perfect shape. I drove around after and its acting exactly the same, the rpm's are dropping very slowly and when I come to a stop it idle's @ 1100-1200 rpm's.( with O/R x and SLP's its vey noticeable) haha,? im confused

well 1st-off, you paid waaay to much for it, now what year is your car and what part # did you get?

 

[GT02MG]

I tink it should be mandatory that ford should give away a box of IAC for each mustang sold

Haha damn right....mine went up around 25k on the clock

 

[XtorT'r]

You should be able to clean it with either electrical cleaner or carb& choke cleaner. You should be able to reset your IAC after you clean it. I still have to do that, I'll try to find the instructions on that and post it.

 

[Sonicpony]

well 1st-off, you paid waaay to much for it, now what year is your car and what part # did you get?

that was the MSRP, I paid $52 cause my brother is an employee, 01 GT, it looks exactly the same as the one I took off, its got to be the right one. I'm starting to think now I got a leak somewhere

 

[XtorT'r]

Ok I have some instructions to reset it. I haven't tried this yet because I don't know what the throttle control screw is.
1. Engine off, disconnect negative terminal of battery for 5 minutes, reconnect battery.
2. Disconnect the idle air bypass solenoid connector
3. Start engine and run at 1800rpm for 30 seconds.
4. Place automatic transmission in park, manual in nuetral.
5. Check/Adjust idle rpm, turn the service spacer trim screw to 500RPM.
6. Engine off, reconnect idle air bypass solenoid connector.
7. Start engine and stabilize for 2 minutes, goose engine and let it return to idle.

 

[Sonicpony]

sounds good I'll try it tommorrow

 

[Stang|ess]

did you install a tb? if so, check your tps voltage.

also, if that doesn't work, start your car on a cold engine and allow it to warm up without touching the gas. after it does, shut her off, then start her up again.

 

[Sonicpony]

ya I got the mother of all crappy TB's, MAC 75mm,I tried the 7 step thing and with the IAC unplugged it idled @ 500 rpm and sounded awesome, like it had cams or something! but when I plugged it back in it was back to 1000 rpm, its probably the TPS voltage, IM gonna give my stang shop a call and if they agree, im gonna let em do it, I dont feel like buying a volt meter and fig. how to do it. Im pretty sure the 01 TPS are not suppose to be adjustable and to adjust it you have to widen on of the bolt holes??

 

[MissBlondie]

I tink it should be mandatory that ford should give away a box of IAC for each mustang sold

No kidding! The last 3 mustangs I've had ended up having it replaced.

 

[rs-turbo]

Ok I have some instructions to reset it. I haven't tried this yet because I don't know what the throttle control screw is.
1. Engine off, disconnect negative terminal of battery for 5 minutes, reconnect battery.
2. Disconnect the idle air bypass solenoid connector
3. Start engine and run at 1800rpm for 30 seconds.
4. Place automatic transmission in park, manual in nuetral.
5. Check/Adjust idle rpm, turn the service spacer trim screw to 500RPM.
6. Engine off, reconnect idle air bypass solenoid connector.
7. Start engine and stabilize for 2 minutes, goose engine and let it return to idle.

What happens if you don't do this? I replaced my IAC a month or so ago and added a restrictor plate. I disconnected the battery then figuring it resets to a default setting. The idle was high then and triggered the Engine Service light after two weeks. I removed the plate, disconnected the battery again, and idle was back to normal. But when I started using the AC, the idle began to fluctuate. It sat at 700, would rise to 1200-1500, then drop to 500 and level back at 700 for a bit until it restarted the cycle. Without AC it idles normally. This past weekend the AC idle seems to be coming back to normal after a long trip with AC. I'm thinking the computer is learning, but wonder if because I didn't do the above steps this might be the cause. I have another thread going on with others having similar issues with their AC idle. This only started after the IAC swap.

 

[XtorT'r]

What happens if you don't do this? I replaced my IAC a month or so ago and added a restrictor plate. I disconnected the battery then figuring it resets to a default setting. The idle was high then and triggered the Engine Service light after two weeks. I removed the plate, disconnected the battery again, and idle was back to normal. But when I started using the AC, the idle began to fluctuate. It sat at 700, would rise to 1200-1500, then drop to 500 and level back at 700 for a bit until it restarted the cycle. Without AC it idles normally. This past weekend the AC idle seems to be coming back to normal after a long trip with AC. I'm thinking the computer is learning, but wonder if because I didn't do the above steps this might be the cause. I have another thread going on with others having similar issues with their AC idle. This only started after the IAC swap.

Well all I know is that sometimes your "supposed" to reset it after you clean or replace the IAC. I think it is normal for your idle to change slightly when your Air conditioning is on. That is from the compressor engaging and disengaging.