1993 ford f-150 4.9L EFI

Recently got a IAC valve from a junk yard and replaced my stock one. It came from an identical motor. Engine Idle seems slightly higher than it used to, but as I turn on the A/C compressor, the idle will increase significantly.

I replaced my other one because I took it off to clean it and as I put it back on it cracked around a bolt hole. (I was surprised, it didn't take much)

Does this sound like an IAC valve issue or something like a vacuum leak? Should I just buy a new IAC valve or is there a legitimate test procedure for it?

Thank you for any help.

-M_J

 

Idle speed should increase when the AC clutch engages.. that is normal.

How much of an increase are you seeing?
Did you measure your "new" TPS to see what it produces at closed and wide open throttle? FYI.. closed should be 0.9 to 0.99v but not over 1.0v and WOT at something around 4.5v.

 

Idle increases to at least 1400 with a/c compressor. You say TPS, was those values for TPS, or did you mean to type IAC? I have not touched the TPS.

Thanks.

 

bought my truck form original owner with 100,000 miles on it and it has done that form the beginning. figured it was normal.