Just killed the golden goose!

J.D.

SCCoA Member
Took the car out for its weekly drive. When I shut the engine off I heard a baby goose honk. I've read the threads on the IAC and have a specific question: Could the IAC cause a bad (low rpm) idle in Drive only and not in Neutral or Park?
 
In a word, Yes...

There is some amount of load on the engine while idling in Drive, that along with a bad IAC will cause the engine to idle too low, or possibly even stall.
 
I should have been more precise. The rpms in Drive at idle sometimes drop a few hundred rpm all of a sudden. So I don't think that the engine load is a factor.
 
yeah ur IAC is bad... replace it as soon as possible with an OEM from FORD. especially since u have a AUTO... watch keep driving it like that and then the RPMS are gonna start to RACE UP...
 
The Idle Air Control has a torn diaphram and needs replaced. Make sure you get one like the original one or get a Motorcraft part.

Jerry
 
Darkstar_one, thanks for the warning. Your answer (high rpms) and my symptoms (low rpms) would mean that a bad IAC can cause the rpms to either rise or drop! This piqued my curiosity and I looked up the description of the IAC in the manual. This is what I found:

The IAC is used to control engine idle speed by allowing air to bypass the throttle plates for:

1) Cold engine fast idle - This would explain why I have recently had trouble starting from cold.

2) No touch start - The last few times I've had to press the accelerator when starting.

3) Dashpot - I don't know what this means.

4) Over temperature idle boost

5) Engine idle load correction - I think it would explain what LJGriggs referred to in post #2 about engine load in Drive.

The Nippondenso IAC can be identified by a black plastic housing. Do not use cleaning solvent on this valve. To service this valve, replace it.
 
J.D. said:
Darkstar_one, thanks for the warning. Your answer (high rpms) and my symptoms (low rpms) would mean that a bad IAC can cause the rpms to either rise or drop! This piqued my curiosity and I looked up the description of the IAC in the manual. This is what I found:

The IAC is used to control engine idle speed by allowing air to bypass the throttle plates for:

1) Cold engine fast idle - This would explain why I have recently had trouble starting from cold.

2) No touch start - The last few times I've had to press the accelerator when starting.

3) Dashpot - I don't know what this means.

4) Over temperature idle boost

5) Engine idle load correction - I think it would explain what LJGriggs referred to in post #2 about engine load in Drive.

The Nippondenso IAC can be identified by a black plastic housing. Do not use cleaning solvent on this valve. To service this valve, replace it.


J.D., I bought an IAC from the local Ford dealer here, last summer and it was around $105.

Did that golden goose lay a golden egg before you off'd it? :D
 
J.D. you can get the same exact part from places like Advanced or Autozone and it will cost around $40. Just make sure it looks the same before you buy it.

Shane
 
quick35th said:
J.D. you can get the same exact part from places like Advanced or Autozone and it will cost around $40. Just make sure it looks the same before you buy it.

Shane
Can I get the gasket from them? The last time I cleaned it (with 98% alcohol only!) I had to make one.
 
NCredSC said:
J.D., I bought an IAC from the local Ford dealer here, last summer and it was around $105.
............................
$105 for a measly solenoid? You must be the local Ford dealer's golden goose! :D

NCredSC said:
...........................
Did that golden goose lay a golden egg before you off'd it? :D
Yes, but the moose call caused a stampede and I lost it. :D
 
Last edited:
quick35th said:
It comes with one.

Shane
Thanks, but I need the gasket only. I have spare IACs. I guess it doesn't really matter as it's easy to make. I just wanted it to look "proper" (said with a British accent). :)
 
173 dollars with no gasket at ford in Canada ...I couldn't bend over for a week after that trip ..to the ford stealer ship..I mean dealer.ship..basicly if you can blow through one of the 2 holes and hear air coming out the other hole it is shot...if not gasket is leaking ....dave
 
Can an IAC also cause poor gas milage. Mine will run down the road fine. But if you cold start or run the car to operating temp and then try and idle in drive (drive-thru's) or in nuetral with or without A/C it will idle down and then come back up and go down and back and forth a few times and then kill. I also have noticed since this happened that my fuel milage has went to s**t. I dont have exact numbers for the fuel milage I never cared but I can really tell the difference and I just tuned it up a while back with new iridium plugs and brand new wires and cleaned the throttle body with O2 safe cleaner and it was running great for a little over a hundred miles (a couple months worth to me I drive a big rig and go out 3 weeks at a time). I also can smell the fuel is inriched at the exhaust. No check engine light but I am confident I would miss the engine if it was missing or stolen. BTW the the up and down idle isnt instant it usually takes a minute or a little more of perfect idle before it starts. Also if it dies it is hard to start meaning it takes about 3 five second hits of the key and then its off to the races again for a minute and then it dies. It's like each time it dies it wants to die a little sooner then the time before and I even mashed on it a few time to try and blow the cylinders out. SOrry for the long post but to much info s better then to little I hope.
 
Mine had been doing that and finally my cam sensor died. The hard restart is what made me think yours is the cam sensor going out. I replaced my IAC a few months back cuz of the noise it was making at idle and shutting the car off (if you hit the gas when you shut the car off it bypasses the honk sound).

Anyways mine would just randomly shake and want to stall so I'd have to throw it in neutral at a red light. The fact my motor mounts need to be replaced make the vibration all the worse.
 
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