• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

Engine surging idle

  • Thread starter Thread starter mercurycapri
  • Start date Start date Aug 26, 2021
M

mercurycapri

Member
May 30, 2006
211
2
18
washington
Aug 26, 2021
#1
  • Aug 26, 2021
  • #1
I have a 82 mustang I just installed the motor and transmission from a 1990 crown vic. Everything is stock except for a long tube headers, dual plane intake manifold and a 2 barrel 500cfm holley carburetor that I took off my truck which has a 390fe motor. My truck ran good with the carburetor but on my mustang its surging at an idle and when I drive it surges. When I start it when it's cold it idles and surges and doesn't changed when warmed up. I took the jets out to check if they were plugged which they weren't. I noticed that the jets are 73 size which I think is a bit large for my engine. Could the big jets be causing my issue?
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
27,827
10,508
203
polk county florida
Aug 27, 2021
#2
  • Aug 27, 2021
  • #2
I think the jets are not causing the surge, check power valve for damage and check for vacuum leaks.
A leaking power brake booster can cause this as well,
A couple questions: was the carb rebuilt and does it act up with the vacuum advance plugged?
 
Reactions: Gs1987GT
You must log in or register to reply here.

Similar threads

9
Electrical F150 ECU in a Foxbody? Idle surge help
  • 93royalblue
  • Sep 10, 2025
  • Fox 5.0 Mustang Tech
Replies
6
Views
377
Fox 5.0 Mustang Tech Sep 17, 2025
Mustang5L5
K
Procharger Stage 2 - 2013 Mustang GT Minor Hiccups
  • KHills5058
  • Oct 9, 2025
  • 2010 - 2014 Specific Tech
Replies
0
Views
118
2010 - 2014 Specific Tech Oct 9, 2025
KHills5058
K
K
2013 Mustang GT Procharger Stage 2 Kit Issues
  • KHills5058
  • Oct 9, 2025
  • 2005 - 2014 S-197 Mustang -General/Talk-
Replies
3
Views
221
2005 - 2014 S-197 Mustang -General/Talk- Oct 10, 2025
KHills5058
K
SURGING IDLE / NO IDLE CHECKLIST FOR 1996–1998 MUSTANG GT (4.6L 2V) - Work In Progress
  • Noobz347
  • Aug 30, 2025
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
654
1996 - 2004 SN95 Mustang -General/Talk- Aug 30, 2025
Noobz347
SURGING IDLE / NO IDLE CHECKLIST FOR 1999–2004 MUSTANG GT (4.6L 2V) - Work In Progress
  • Noobz347
  • Aug 30, 2025
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
801
1996 - 2004 SN95 Mustang -General/Talk- Aug 30, 2025
Noobz347
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?