Cold blooded rough idle -

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.
Sponsored by:
Sponsored by:

Thread Tools Search this Thread
Old 05-16-2013, 10:11 AM   #1
Thread Starter
Join Date: May 2013
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
Location: Spfld, MA
Posts: 9,240

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
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

Related Topics
Thread Thread Starter Forum Replies Last Post
4 Valve Head questions GimpyHSHS 4.6L (1996-2004 Modular) Mustang 7 06-17-2017 12:18 PM
Intake manifold replacement Dokilar 4.6L (1996-2004 Modular) Mustang 15 10-16-2015 08:13 PM
TNT, New PB TCStangerv6 Street/Strip 12 10-11-2015 05:57 PM
Starting Issue svfetter 5.0L (1979-1995) Mustang 9 10-05-2015 11:39 AM
Rough idle and vibrating 4cylinderplus2 V6 (1994-2004) Mustangs 9 09-30-2015 05:26 PM

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

All times are GMT -5. The time now is 01:24 PM.