MAF - IAC Difficulty

[woodyedmiston]

Cleaned the IAC and the MAF at the same time before I started the truck again. Now the truck does not idle correctly. 99 4.0 Auto should idle around 900 rpm. Now idles so low the truck will die when I put it in gear if I don't watch.

What did I do?

 

[Wicked_Sludge]

more likely the fault of the MAF then the IAC. sounds like you may have damaged it while cleaning.

 

[woodyedmiston]

Wicked,
What does the electronic coil attached to the throttle butterfly on the outside of the intake do? How is it re-installed. I took it off too - without actually intending to but my neighbor was talking to me - and it seems to be an electronic throttle stop or idle advance.

As for the MAF, I took it off, soaked it and replaced it. I didn't touch anything even close to the filaments.

The IAC did not move freely. Maybe I should just replace it.

 

[Wicked_Sludge]

the only electric coil attached to the outside of the TB is the IAC solenoid. the PCM uses that to control the engines idle. the only other sensor in the area of the TB is the throttle position sensor, though it isnt a coil. that relays the position of the throttle to the PCM.

 

[woodyedmiston]

I've looked this up on the Autozone computer and found it is called the Idle Solenoid. The problem I have - if this were a carbureted ford - would be fixed by adjusting the idle screw. I've taken off and removed this thing a couple of times and can't get it to work. Otherwise the truck runs fine - actually better than before I cleaned the MAF - can you direct me to a site that might tell my how to reinstall the thing? I'll buy a new one if I have to, but if there is a trick to installing it that won't help.

 

[Wicked_Sludge]

theres no trick. its just 2 bolts and one electrical connection. if there is no change in the idle between having the solenoid plugged in and having it unplugged then its probably junk and should be replaced.

 

[woodyedmiston]

Junk

Well alrighty then. Autozone doesn't sell it - maybe a Ford part, huh?

 

[Wicked_Sludge]

most auto part stores will have one in stock. any parts store should be able to order one. autozone carries them, their part number is AC473.

 

[Earl43P]

Leave TPS connected and backprobe its wires with a voltmeter till you find the signal wire.
Adjust it so that at key on, engine off, throttle at rest, signal wire reads .96V.
Then disconnect battery and turn lights on to reset PCM.

 

[woodyedmiston]

Backtrace?

I think I can manage that. Thanks for the tip. But how do I "adjust" it?