MustangWorks.com - The Ford Mustang Power Source!

Go Back   MustangWorks.com : Ford Forums > Mustang & Ford Tech > Windsor Power
Register FAQ Members List Calendar Mark Forums Read

Reply
 
LinkBack Thread Tools Rate Thread Display Modes
Old 10-09-2005, 07:11 PM   #1 (permalink)
brett p.
Registered Member
 
Join Date: Oct 2005
Posts: 1
Default idle air control valve problems on a 91 5.0

I have a 91 5.0 mustang with a 5 speed. The motor is pretty much
stock execpt for roller rockers, headers, pulleys, the mass air
meter, 65mm throttle body, and a cold air intake. The vehicle was running fine with this combination. In fact it was running quite well until I put a Trick Flow street intake on it about a month ago. What happens is that the vehicle idles good and runs very well, but when I start to come to a stop and lets say I'm running 2k rpm and I push the clutch in and take my foot off of the accelator it sometimes wants to shut off. The vehicle cranks up fine and runs normal, but its annoying to have it shutting off while I'm coming to a stop. One mechanic told me it was either a vacume leak or the IAC valve. I checked for vacume leaks and could not find any. I replaced the IAC valve with one from Advance Auto Parts, and it doesen't shut off as much as the stock unit, but every once in a while it will. Any help will be appreciated. I have to fix this problem. Thank You.
brett p. is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
Old 10-10-2005, 08:39 AM   #2 (permalink)
Jeff Chambers
Moderator
 
Jeff Chambers's Avatar
 
Join Date: Aug 2000
Location: Milan, OH
Posts: 2,699
Default Re: idle air control valve problems on a 91 5.0

You've changed the airflow into and out of the engine. What is happening is that the idle dashpot isn't sufficient enough to keep the engine from stalling on de-clutch. A good tuner would be able to adjust the idle preposition, dashpot and isc neutral air to restore the driving quality. Word of warning, if you attempt to add idle air by adjusting the idle stop screw on the throttle body, you'll most likely end up with a flare on the shifts and a surging idle. A custom tune is really the way to solve the driveability issue.
__________________
Jeff Chambers
1990 Mustang GT 10.032 Seconds / 137.5 MPH
14-time Street Warrior World Record Setter
CRT Performance
2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH
2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2

"There's nothing boring about a small block automatic shifting gears at 9400 rpm!"
Jeff Chambers is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
Old 10-12-2005, 01:32 PM   #3 (permalink)
HoodStrype
Rearview Mirror Haze
 
HoodStrype's Avatar
 
Join Date: May 1999
Location: Huntsville, Alabama...a.k.a. "HuntsVegas"
Posts: 387
Default Re: idle air control valve problems on a 91 5.0

Quote:
Originally Posted by Jeff Chambers
A good tuner would be able to adjust the idle preposition, dashpot and isc neutral air to restore the driving quality.

Thanks Brett! You inadvertantly got that question answered for me as well. I don't want to take over thread, but what is a dashpot/ idle preposition/ isc neutral air? Does someone have a link showing how to do this one? I got major surging after fixing my vacuum leaks and adding a 1" spacer... Sorry Brett- I fugured you might ask anyway.
__________________
93 lx Notch
01 GT

...the epitome of Murphy's Law
HoodStrype is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
Old 10-12-2005, 10:06 PM   #4 (permalink)
Jeff Chambers
Moderator
 
Jeff Chambers's Avatar
 
Join Date: Aug 2000
Location: Milan, OH
Posts: 2,699
Default Re: idle air control valve problems on a 91 5.0

These are all parameters or tables found in the PCM. They have to be accessed & changed through a custom program (chip). We use the SCT Advantage (Superchips Custom Tuning) at our shop but a shop using Autologic, Diablosport/Chipmaster, or other custom tuning software can make the necessary tuning changes for you.
__________________
Jeff Chambers
1990 Mustang GT 10.032 Seconds / 137.5 MPH
14-time Street Warrior World Record Setter
CRT Performance
2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH
2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2

"There's nothing boring about a small block automatic shifting gears at 9400 rpm!"
Jeff Chambers is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
Old 10-19-2005, 01:15 PM   #5 (permalink)
Hethj7
Mizzou Tigers
 
Hethj7's Avatar
 
Join Date: Apr 1999
Location: weston, MO United States
Posts: 1,455
Default Re: idle air control valve problems on a 91 5.0

Jeff, thanks for the info. I don't have my Stang anymore, but I fought that problem for years with it. All the IAC changes, resetting computer, changes to throttle screw position, etc. never seemed to totally eliminate my problems. This is the first I've heard of the parameteres you mention. Good info to know for future reference. Thanks! ( I am already planning out my next Stang purchase for this spring...the Conturd has got to go )
__________________
2006 Mustang GT

1990 LX
GT-40 motor 262 horsepower, 307ft-lbs (sold but forever loved)

1998 Contour SVT

Rice Haters Club Member #244
Hethj7 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
Sponsored Links
Reply


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



Similar Threads
Thread Thread Starter Forum Replies Last Post
Idle Air Control Help!!! smokesix Modular Madness 1 09-19-2003 06:35 PM
PCV Valve what the ?@#$@#$@$ Chevyguy Windsor Power 3 04-11-2001 09:01 PM
Idle Problems Here- Surge, Lope, Stall, etc... slo95 Windsor Power 8 03-19-2001 02:26 PM
Idle problems & slight surging Saleen308 Windsor Power 8 03-17-2001 07:21 PM
Idle Problems 86GT Windsor Power 2 03-13-2001 12:00 PM


All times are GMT -5. The time now is 09:47 PM.


SEARCH