Problem or Normal?

[Shakerhood]

I dont get to drive my Stang to often, maybe once every couple weeks or so, but I drove it to the Store this evening and noticed something and I am not sure if its a problem. When I pulled up to a red light the Idle stayed at about 1000 RPMs for maybe 5 or 6 Seconds before dropping down to about 750 RPMs. I was pretty tough on it on the way home and did not get any lights Red and so I didnt get to see if it did the same thing. Do you think its anything to worry about, or just a case of sitting?

 

[z2o_what]

my '86 used to do that from time to time, especially when it wasn't warmed up. i never thought of it as a problem, just nature of the car.

 

[Shakerhood]

My Memory is getting worse as I get older, so I am hoping the car always did it, or that it was just the fact that I havent had it out in a few weeks. It really didnt seem like that big a deal because it did settle down to normal Idle, it just took 5 or 6 Seconds.

 

[HISSIN50]

Did you have the AC on? Mine was doing that awhile back (also seldom driven) and it spit an Idle limit code. The IAC was fritzing.

I did nothing about it and it seemed to fix itself once I drove it a bit more.

Good luck bud.

 

[Shakerhood]

Thanks for the Help, no the A/C wasnt on, it is hopefully just an issue from inactivity. I really drove it hard coming home, I was goosing the Go Pedal like crazy and enjoying the Exhaust Note plus the car felt great!

 

[Shakerhood]

I drove it again today and it did the same thing, but I counted how long it took to drop down and it was between 3 and 4 Seconds.

 

[HISSIN50]

Was your recollection a little off when you typed last night, or is it slowly getting better?

If it's bothersome, I might pull codes just to see what it says and then clean the IAC out.

That's the best I got.
Good luck bud.

 

[bullitstang1313]

Thats normal operation for the Idle Air Bypass solenoid (IAC) during cold start drive away. It does this to keep the car from stalling out before it gets warm. This is only a problem if it is doing it after the car has warmed to normal operating temperature.

 

[QUIKSVT]

I've had the same problem. Its the IAC as stated above. In my case, it did the exact same thing right before it completely crapped out and would then just idle at 1800 rpm. I think the heat, or something causes them to lock up in the open position. Try spraying it out with carb cleaner. If that doesn't work, head down to the junk yard and grab a couple of the damn things, usually like 10 bucks around here. I found two of them at the local yard that were brand new. Beats paying 80 bucks for a new one, only to smoke it too.

 

[bubba-dough]

+1 for whats already been stated. Nothing new to add.

 

[Shakerhood]

I've had the same problem. Its the IAC as stated above. In my case, it did the exact same thing right before it completely crapped out and would then just idle at 1800 rpm. I think the heat, or something causes them to lock up in the open position. Try spraying it out with carb cleaner. If that doesn't work, head down to the junk yard and grab a couple of the damn things, usually like 10 bucks around here. I found two of them at the local yard that were brand new. Beats paying 80 bucks for a new one, only to smoke it too.

The IAC was mounted on or around the Throttle Body Correct?

 

[QUIKSVT]

The IAC was mounted on or around the Throttle Body Correct?

I've never seen one anywhere else? They bolt to the side of the TB, they have to be there to allow or disallow airflow around the butterfly to maintain idle.

 

[Shakerhood]

I've never seen one anywhere else? They bolt to the side of the TB, they have to be there to allow or disallow airflow around the butterfly to maintain idle.

Yep, thats it, I checked it out in my Service Manual, I will pop it off and spray some throttle body cleaner through it and make sure it is nice and clean.