Cold blooded rough idle -

Go Back > Ford Mustang Tech > 5.0L (1979-1995) Mustang
Sign in using an external account
Register Forgot Password?

5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.

Cold blooded rough idle

Thread Tools Search this Thread
Old 05-16-2013, 10:11 AM   #1
Join Date: May 2013
Vehicle: 1990 ford mustang
Location: Maine
Posts: 12
Default Cold blooded rough idle

Why do I have such a cold blooded rough idle on my 1990 5.0 after a e303 swap? It's got hedders and flow master exhaust, thanks
90notchback90 is offline   Reply With Quote
Old 05-16-2013, 10:54 AM   #2
6th Gear Member
mattdel's Avatar
Join Date: Nov 2006
Vehicle: 1986 LX, 87 GT Hatch, 89 GT Vert
Location: Spfld, MA
Posts: 9,240
Send a message via AIM to mattdel

2 reasons: user error when reinstalling rockers, or you never did a base idle relearn.
mattdel is offline   Reply With Quote
Old 05-16-2013, 07:03 PM   #3
2nd Gear Member
89StangGTConvertible's Avatar
Join Date: Jan 2011
Vehicle: 1989 Ford Mustang GT Convertible
Location: Maryland
Posts: 158

Try resetting your idle, as Mattdel suggests. It's easy to do (my idle is set at 1,000 rpms, but that's just my preference with electric fan, etc.):

1. Disconnect your negative on your battery to clear/reset your computers memory. caution when ever you disconnect your battery remove the negative first then positive, reconnect in the reverse order, if you don't you can possibly cause a battery explosion or destroy your computer. Leave your battery disconnected for at least 30 mins to let the capacitors in the ECM to discharge fully.

2. Disconnect the IAC connector.

3. Reconnect your battery.

4. Start the motor, with the IAC plug disconnected.

5. Set your idle, via the stop plate screw on the throttle body, between 650-850 rpms, it is best to set it at the lowest setting to prevent idle problems, such as surging, rolling etc.

6. Turn the motor off and reconnect the plug on the IAC.

7. Start the motor at let it run for 2-4 mins at idle with all accessories off, if the motor stalls out or the idle drops to low repeat steps 4-6.

8. Once your idle is good, turn the motor off and wait 2 mins, then start it back up and run for another 2 mins with all accessories on.

9. Allow 10-20 mins to let the computer "relearn" under normal driving conditions.
89StangGTConvertible is offline   Reply With Quote
Old 05-16-2013, 07:03 PM
Ford Mustang

Paid Advertisement


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 Off
Pingbacks are Off
Refbacks are Off

Forum Jump

Featured Sponsors
Vendor Directory
New Sponsors
All times are GMT -5. The time now is 07:24 AM.>

© Internet Brands, Inc.

This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. Ford® is a registered trademark of the Ford Motor Company
Emails Backup