1991 Ford Ranger High Idle

[91 blue ranger]

Ok will do I will. I will respond back with what I find.
Yes the TB was used.

 

[91 blue ranger]

Where did you get your iac?

I got one from 1A Auto and a different one from the junk yard I got the TB.

 

[91 blue ranger]

Warmed it up and turned the Anti diesel screw. Did not help. Still idles at 850 900 when iac is pluged in or not.

 

[RonD]

OK, vacuum leak then

 

[91 blue ranger]

Yeah I will report back after I make my smoke leak detector. It will be a few days until the parts come for it.

 

[RonD]

Cheap cigar and a bottle of scotch
Cigar is optional

Pull off power brake booster hose, puff cigar blow smoke into hose
Drink some scotch
Repeat

 

[RonD]

You could also test the TPS on the new, not that it works, that is not holding the throttle plate open a bit
Warm up engine, unscrew it and take it off the plates shaft and start up the engine, then unplug IAC Valve and see if RPMs drop, also try anti-diesel screw again

3rd party TPS can hold throttle open a bit

 

[Monkeyboy]

Did the used throttle body come with a TP sensor?

 

[91 blue ranger]

Yes it did. But I think it is an aftermarket one because it is a little smaller and doesn't have the ford symbol on it.

 

[91 blue ranger]

My soldering iron came and I made and tested the smoke machine, and will work great. Now I have to wait for my brother to come home from plowing.

 

[91 blue ranger]

So I looked for leaks and I did not find any. I had a lot of smoke in the manifold so something should have leaked if there was a leak. It did leak out of the air box ( behind the Maf sensor) so not a problem. So I do not know what is up.
After fully warmed up it idles at 900 even if the iac is unplugged. Any thoughts. It runs pretty good so I might be ok with it. It is better than it was. Thanks for all your help everyone.

 

[RonD]

You need to turn the engine 180deg then test, turn 180deg then test, ect...........until you have turned it a full 720deg, 2 full turns
This allows smoke into all ports , i.e. if intake valve is closed very little smoke goes that way

 

[91 blue ranger]

Ok how should I turn the engine? Just wondering how this will make a difference.
Thanks.

 

[RonD]

bump it with starter, unplug coil

Probably won't, but warm engine at 900rpm and IAC Valve unplugged means there is a problem with air entry, period
So could be throttle plate, IAC Valve, they are not closing enough, or vacuum leak
Those are the options

I would add distributor if it was a 2.9l or 3.0l, lol

 

[PetroleumJunkie412]

Just for laughs, and to entertain me if no one else... Mind doing the Ron style smoke test, but leave your oil filler and radiator cap off? See how much smoke leaves either.

How do the grommets on your valve covers look?