1996 F250 460 High Idle Issue

[grangr]

Just bought a 1996 F-250 supercab 4x4 with a 460 and manual transmission with a high idle issue. I checked for vacuum leaks but can't seem to find any. Anybody have any experience working on these or know of a solution?

Thanks,
Greg

 

[Seabass]

I've had several of these trucks- none with a 460. But I bet the intake is real similar on all the motors of that vintage. Check out the air idle control valve. It could just be dirty and sticky, or need replaced. You can clean it with a baby bottle brush and some throttle body cleaner.

 

[grangr]

Tried that this evening but no change. It was pretty dirty so will probably pick one up and switch it out.

Thanks for the quick reply.

 

[MikeBoyle]

Does unplugging the IAC while the engine is running affect the idle? If the idle doesn't drop with the IAC unplugged it (the IAC) is stuck and likely the cause of the high idle.

 

[grangr]

I tried that and it did not change. Will switch it out this weekend.

Thank you.