Surging and High Idle Problem

[RangerMan64]

Hello,

Ever since I bought this truck (1988 Ranger 2.9L), I've had idle issues. It usually idles pretty high (1000-1200 RPM when warm) and it surges a little. Also, sometimes when I am backing out of a space, it stalls without warning, but restarts fine. Also, when I am driving it and shut if off at a gas station, and restarts, the truck stumbles and almosts dies, going down to about 400 RPM, but recovers.

So what should I have a look at? Throttle body and IAC were cleaned not so long ago, it gave me better throttle response but didn't solve the idle issue. For some reason, the motor will actually idle where it is supposed to, with no surge.

Thanks

 

[RangerMan64]

Anyone?

 

[m8r8j]

was having the same problem on my 02 explorer 4.0...

i cleaned the iac and maf with some maf cleaner, and the problem continued... turns out the iac was bad..... sometimes u just gonna replace em

 

[RangerMan64]

Thanks m8r8j,

Is there a way to test the IAC valve? What brand did you use to replace it?

 

[Nhaz]

The iac on my 1992 is pretty much just a solenoid. I unbolted it from the top of the intake manifold disconnected it from the wiring harness. and applied 12 volts dc to its terminals. and watched the internals move back and forth as the solenoid got power and then lost power.


This told me my iac was working.

 

[RangerMan64]

Yeah, I ended up looking up how to test, and it tested good.