Do I have an IAC problem?

["Turbo-T"]

When I drive my TR, I can let off the accelerator at....35....40...45...50...55....and it sort of acts as if either the cruise control is on (it's not) or if the accelerator cable is stuck.

The engine will quit pulling but the idle is high.

If I put the car from drive to neutral, the rpms do not come back down. Not for at least a few minutes.

So I flipped to the IAC mode on my Scanmaster.

Cruising at 55 mph, when I let off the accelerator, the IAC was reading 57. That's with the car coasting.

When I put the trans in neutral, the IAC dropped to 47.

The idle eventually comes back down but not until a few minutes later, after being put in either neutral or park.

Does it sound like I have an IAC problem? How can I fix it?

Thanks.

 

[Blazer406]

With the info provided..... probably not....

Have you checked for vacuum leaks? What chip? What are your BLM's? What do the IAC numbers do at idle....after it comes down? .... before it comes down?

 

["Turbo-T"]

Yes, I have yet to have found any vacuum leaks. Turbo Tweak 93 street chip. BLM's I'd have to double check, I think they're between 120 and 130.

IAC numbers at idle are usually 0 if the car's not been running around. It takes a few minutes for the idle to come down after putting the trans in park or neutral. Why?

 

[Blazer406]

Yes, I have yet to have found any vacuum leaks. Turbo Tweak 93 street chip. BLM's I'd have to double check, I think they're between 120 and 130.

IAC numbers at idle are usually 0 if the car's not been running around. It takes a few minutes for the idle to come down after putting the trans in park or neutral. Why?

The IAC is 0 becaus the ECM is trying lower the idle... so it shutos off the IAC.... hence the 0 value... if you close the throttle via the set screw.... when the car is idling.... it should come up of 0..... make sure the throttle isn't sticking when it returns back closed after you let off... Like I said... once you set the IAC.... readjust the TPS.

Think of the IAC like the ECU's own little throttle blade.... 0 is closed... and 100 is wide open.... when the ECU needs to lower the idle... it closes the IAC...(lower number) ... since yours is bottomed out at 0 ... the ECU can't lower it any more...

Report back....