Lately, i've noticed that my truck will dramatically drop in RPMs when i go from either Drive or Reverse, into Park. Yes, I know it is normal for it to drop somewhat.. but lately it's been kinda bad.. it'll drop down to about 300, and feel like it's going to stall, but never will.. it'll just sit that low till i give it a little gas, at which point it climb back to normal while in Park.

Anyway.. i figure i might have a sensor going or something like that.. anyone have any idea what it might be?? im going to change my oil tonight, so i figure i might check some stuff while im doing it. Thanks guys.

 

does it make a whistling noise? cuz mine has the same problem... its the IAC...

 

nah no whistling noise.. there's really no noise at all (other than the normal engine noise you'd hear..). it just drops and feels like it's gonna stall, but wont.

 

My truck has been doing that when I start it up. I've got a manual though. The revs will drop down, it'll feel like it's going to stall, and it won't respond to the throttle for about a second or two. It's been doing that ever since I put a new alternator in, can't imagine how the alternator has anything to do with it though!

 

its the IAC almost positive. same problem with mine once i replaced it it was fixed. its like 40$ from ford or something like that.

 

whats the IAC, and where does it go/what does it do? forgive my ignorance!

 

Idle Air Control

It controls your idle , it should be attached to your throttle body (atleast mine is)

Best thing to do, if you dont know what it looks like, go buy one, and find the part on your engine.

Should be near the Intake Manifold somewhere. And replace it. :)

 

it controls the idle somehow its the silver thing close to the throttle body.

if bob chimes in he could give you more info.

it can be clean with some electronics parts cleaner.

 

thanks guys, i just looked up IAC on google for the hell of it too.. they say the same thing.. except one said they dont recommend cleaning it, as it is a nonservicable peice, just replace it.. i guess they're saying that for safeties sake?

anyhow, thanks guys! ill go to ford tomorrow afternoon i guess and order a new one. (bob, if you see this thread, let me know whatever you have to add!! it can only help, lol. thanks!)

 

The IAC is a computer controlled air bypass around the throttle plate. The PCM uses it to control the engine idle speed and also how fast the manifold vacuum increases when the throttle is closed for deceleration.

It is possible for the IAC to stick when it gets old and gummed up or if contaminated with dirt from poor air filtration. I have heard that they can sometimes be cleaned but I have never done that myself.

 

Mine was cleaned

Its ghe gunk getting in the way if its THAT dirty..

Yours prob just need replacing. Its safer.

 

i used t-body cleaner and a small soft brush... it worked

 

they actually wear out.. cleaning doesnt fix that. or it does but only temporarily.
The parts slide with no bearings or anything.

Rand

 

this is WAY old but for cleaning should you use throttle body cleaner or electrical cleaner...or does it matter? I just dont want to mess something up...and what should i use for the mass airflow sensor?

 

Zach you said $40 dollars so i called my local ford dealer as i need a new one 2 and they said $118 so i called bumper to bumper and they said $120. Whats the deal with this? First time Dealer has been sheaper i think though.

 

Do you have a cold air intake? I replaced my iac and it didnt fix anything. I had the same problem with mine and i took the cold air off and it quit... It affects the wonderful finicky maf so much that it wont idle. I also have instructions on how to bypass the hpcv system.. I had a problem with that also...

 

Well duh, i just decided to read ur sig!!!

 

lol, yeah, i've got a k&n fipkII on there.. but it was on for nearly a year before the problem started to happen.

but, to update the thread.. i got the IAC from ford and it did nothing for the problem except took my money, lol.. it sort of went a way on it's own towards the end of summer.. i dunno why, or how.. but it went away, lol.

 

ill be willin to bet its the cold air still.... it took mine a while to start doin it

 

possibly.. but why would the problem have gone away? wouldnt many others have the same problem then, being that im certainly not the only one with an intake on my ford ranger?

 

well temperature has a lot to do with drivability issues... the dealer couldnt tell me what was wrong with mine, but all i did was change back to the stock air box for the time bein and it fixed it

 

ya mine is crazy but it makes this marble rattling noise..i hate it!