Idle Problems on warm motor in Park

91StangGT5.0

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Feb 28, 2010

#1

• Feb 28, 2010

• #1

I've noticed that my mustang has been acting kind of strange when it has been driven and then put into park. The idle is fluctuating from ~600(700)rpms-1000rpms and it does it slowly. I have the slightest clue as to what is the culprit to this issue is. IAC? TPS? Other? Thanks!

 

84Ttop

They make new pistons every day, so why worry?

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#2

• Feb 28, 2010

• #2

I would try cleaning the IAC first, then go from there. you may also want to consider looking for a small vacuum leak.

 

91StangGT5.0

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Feb 28, 2010

#3

• Feb 28, 2010

• #3

84t-top said:

I would try cleaning the IAC first, then go from there. you may also want to consider looking for a small vacuum leak.

Click to expand...

How do I go about cleaning the IAC? I also haven't the slightest clue on how to find or check for vacuum leaks.....probably the only thing I can't do correctly for some reason...sad I know

 

84Ttop

They make new pistons every day, so why worry?

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#4

• Feb 28, 2010

• #4

The IAC unbolts w/ 2 bolts check it for carbon build up, they make a special cleaner for it, but i've always just flushed them out w/ some brake cleen. As far as a vacuum leak, check all your hoses and plastic lines for anything visable first.

 

91StangGT5.0

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#5

• Feb 28, 2010

• #5

There looks to be a gasket in there. Would I need to replace this or will it be good to reuse?

 

84Ttop

They make new pistons every day, so why worry?

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#6

• Feb 28, 2010

• #6

if it comes apart cleanly, you can re use them, i have, if it tears, you will need to replace it, only a few dollars at the parts house

 

HISSIN50

"How long does it take to get help in here?

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#7

• Feb 28, 2010

• #7

Does it only wander while in park on a hot motor?

 

91StangGT5.0

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Feb 28, 2010

#8

• Feb 28, 2010

• #8

HISSIN50 said:

Does it only wander while in park on a hot motor?

Click to expand...

Yes it does....it's annoying as hell.

 

HISSIN50

"How long does it take to get help in here?

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Mar 1, 2010

#9

• Mar 1, 2010

• #9

Pull codes, just in case it set a soft one.

How high is your in-drive idle? 700 or so?

If you get it to start wandering while in park, you could try unplugging the electrical connector to the IAC and see if it stops. If so, chances are the IAC or EEC (commanding the IAC) are doing it. If it makes no difference, then the IAC is probably not the cause.

 

91StangGT5.0

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Mar 1, 2010

#10

• Mar 1, 2010

• #10

HISSIN50 said:

Pull codes, just in case it set a soft one.

How high is your in-drive idle? 700 or so?

If you get it to start wandering while in park, you could try unplugging the electrical connector to the IAC and see if it stops. If so, chances are the IAC or EEC (commanding the IAC) are doing it. If it makes no difference, then the IAC is probably not the cause.

Click to expand...

middle of 500 and 1000 rpms...so I guess 700-750rpms? Where should I be idling with a Trickflow Stage 1 Cam, etc?

 

HISSIN50

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#11

• Mar 1, 2010

• #11

91StangGT5.0 said:

middle of 500 and 1000 rpms...so I guess 700-750rpms? Where should I be idling with a Trickflow Stage 1 Cam, etc?

Click to expand...

Depends upon the mods and how the idle was set. 750 RPM would be slightly higher than stock in Drive.

 

91StangGT5.0

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Mar 1, 2010

#12

• Mar 1, 2010

• #12

Here is a video of the problem. It doesn't seem to be the worse of what it usually is....(Go figure when I record huh?). This is what I'm doing in the video....I let it warm up and sit at idle with it in never leaving park, unplugged the IAC, then watched idle, then replugged, watched idle, then put from Park to D, watched idle from gear change, then from D to Reverse, watched Idle change, then changed from reverse to park, watched idle change, revved the engine a little, watched idle, then shut off.

It did not change idle immediately when I unplugged the IAC. I do notice my idle takes a dip when going from one load gear to another...i.e. Drive to Reverse and vice versa. I've had it die on me once if it didn't let it idle for long enough. If I get right in and go from park, reverse, then to drive like from backing from a driveway and drive forward, it would either almost die or die. When I put my shifter in Neutral it idles higher around 1200 rpms most of the time.

ALSO: The ticking noise is an header gasket leak.....stupid bolts on drivers side came loose somehow and blew some of the gasket enough to make a tick. This started yesterday and just waiting on damn backordered gaskets for my headers and ARP Bolts.

http://s298.photobucket.com/albums/mm241/mbonifield04/?action=view&current=MOV00738.flv

 

91StangGT5.0

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Mar 1, 2010

#13

• Mar 1, 2010

• #13

I'll run codes on Wednesday when my Digital Code Reader for my mustang comes in. (Yes, they make code readers for 86-93 Mustangs).

 

HISSIN50

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#14

• Mar 1, 2010

• #14

At least during parts of it, it sounds like a vac leak issue to me if the cam isn't outrageous (i've never run a TF cam).

A header leak could be screwing with the O2 readings on one side.

Is this a MAF car? Is the MAF clean?

Codes and vac leak checks are where I'd start. FWIW, you can pull codes with a safety pin (though the LCD reader makes it easier).