I had my 86 Bronco II at the dealer for some troubleshooting with rough running. They adjusted the timing and told me they wanted to replace the Idle Air Control Valve. They wanted $200 to do it so I decided to do it on my own. I looked in my Haynes manual and couldn't find reference to an Idle Air Control Valve.

Any idea where it is on the 2.9L and how difficult is it to change?

 

Look under air bypass valve in the haynes book.

 

Once you know what it looks like find out what years and motors it fits on at your local parts store. Then go to your local Pick-N-Pull and get yourself a "pocket part" my friends tell me.
IAC for a rover is $270, same damn part used on a chebbie V-6, my friend collected 3 of 'em while checking the yards.
Clean 'em with carb cleaner they spray with dry film moly, good as new.

 

You have both the IAC and the associated solenoid. One or both could be the fault. On the Ford 2.9, it's on the passenger's side of the upper intake plenum. Look at the thread with the pictures HERE. You can pull it off and clean it up, but if the solenoid is acting up and going bad, you're just going to end up replacing it anyway. I'm not so much of a proponent of junk yard parts, however, you might find something that is useable and will last you a while if you want to save some $$$.

 

$2 entry fee vs $269.95 before tax from the Stealers you do the math.
Cleaned then dry film lubed they work like new.

 

Yes, they do, sometimes. But for how long? Until they get gunked up again or fail because the solenoid burns out? That was the only point I was going with. If you can clean existing or junkyard parts up and have 'em work, that's a bonus. However, sometimes that just doesn't work out all the time, and you end up nickeling and dimeing the problem to death and end up spending the $270 you would have spent on a new part. It happens, that's all I was saying. I do regular junkyard shopping, and yes, sometimes I myself pick up parts that I'd otherwise buy new just to get me by. I've just seen that route end up being more headache than it's worth. *shrug*

 

What is the performance degradation with a bad IAC? I don't seem to notice any problem with the idle so I'm wondering what else it can affect.

I've had a consistant problem with random hesitation and would change the IAC if that could possibley help. Otherwise I'm getting sick of changin components on this beast. The thing gets more valuable every day.

 

It takes a lot of nickel and diming to add up to $270 where your hard earned money can be used on something else.
Stepper motors work or not no problem spending a few minutes cleaning a part and testing. I'm not one of those pay the stealers suckers.

 

i had an IAC fail on a 2.9L ranger and it made it idle VERY high, until i replaced it

 

Okay, first off... who said anything about a dealership?? *I* didn't. Secondly, do you realize how much money you are putting into procuring a junkyard part and cleaning it -hopefully- once, if not more than that? Figure in cost of gas from your driveway to the junkyard and back. Figure in entry fee. Figure in cost of said part. Figure in cost of all materials involved in cleaning. Then, figure in the cost of anything that costs money for you to replace it in your garage, if applicable. Now figure out how many times you're going to end up doing all or part of this until you break down and buy a new part versus the cost of the gas to go to and from the auto parts store and the cost of the part and anything required to remove old bad part and install new (or rebuilt) good part. Trust me, the nickels and dimes add up more quickly than you think! And yet again, while I am not a proponent of using junkyard parts all the time, I do believe that sometimes you luck out and can get some good useable (spare) parts at the junkyard and save some $$$ and be good to go in a pinch. For example, I have maybe $50-100 worth of driveshafts that would have cost me well over $1000 to buy new... and they are trail spares in case I snap a driveshaft or eat a U-joint. You've obviously misunderstood what I was even saying.

 

1986 Bronco II 2.9 non CA / Calibration Code parts list: 673 or 677 (parts are identical)

E9AZ-9F715-A .. Throttle Air By Pass Valve

E6SZ-9F670-A .. Throttle Air By Pass Valve Gasket

E6TZ-9C968-B .. Fuel Charger Pressure Regulator Assy (Motorcraft CM-4647)

 

All yours for around $100-150 at the local auto parts store...