High idle

[Chrisboothe1]

Hello I have a 1992 ford ranger 3.0l v6. It has a problem with high idle. It sounds like it idle as at 3000rpm I unplugged the iac and nothing changed it still continued to idle high. I unplugged the MAF and it bogged down. Does this mean my MAF is bad?

 

[Uncle Gump]

No...

You should look for a vacuum leak.

 

[Chrisboothe1]

No...

You should look for a vacuum leak.
[/QUOTE
I drove the truck for about 45 minutes and it ran fine. I parked it and cranked it and it was fine I played with the ac and heat cut the truck off and left it for a day cam back when I cranked it that’s when it started to idle high so I played with the IAC nothing changed the idle but unplugging the MAF it bogged down all the vacuum hose are connected correctly. What should I check next?

 

[Uncle Gump]

you should still be looking for a vacuum leak...

 

[Dirtman]

Also take the IAC off and inspect / clean it. Just because you unplugged it doesn't mean the valve actually shut properly. They can stick when old and dirty. But also... vacuum leak.

 

[RonD]

If you want to test IAC Valve remove it
Then plug in its 2 wire connector
Turn key ON, engine off
Look inside at the valve part of IAC, it should be fully OPEN with key on engine off
Now unplug the 2 wire connector, it should close, only moves 3/8" but MOVES
Plug wires back in and it should open again

Repeat until you confirm it is, OR it IS NOT, moving

And no its metal case does not need to be grounded to engine for it to work, it has 2 wires so + and - are done with those
One of the failure modes of an IAC valve is a short in one contact to its metal case, you can and should test for that with OHM meter, this type of short causes IAC Valve to open and stay open when key is on, and it will test as OK.

Use ONLY Motorcraft IAC Valve as replacement, there have been numerous issues with 3rd party IAC Valves
An old wrecking yard Motorcraft IAC Valve would be better than new 3rd party