• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 1994 - 1995 Specific Tech

Help! Rough idle, hanging idle

  • Thread starter Thread starter zenboy99
  • Start date Start date Apr 13, 2005

zenboy99

Founding Member
May 12, 2002
2,212
0
47
Madison, WI
Apr 13, 2005
#1
  • Apr 13, 2005
  • #1
After a failed TKO install I got sick of my Mustang sitting for 4 months, so I put in a King Cobra clutch. Beforehand the car was idling a little bit rough, and drove a little bit rough at low rpms, but no hanging idle. Now the car idles really rough (~1100rpm compared to 850rpm) and the idle hangs really bad off throttle and down shifting. I still have good power (compared to what I remember), and its not blowing any smoke.

I figured it was a vacuum leak, checked with carb cleaner but didn't find anything. I tore off the whole upper intake and found that one bolt had been stripped out. I found a longer bolt that managed to hold the rest of the threads and could be tightened down pretty good. I put everything back together, but the symptoms still remained.

Took out my JMS chip, same problems. Ran codes and found nothing.

The only thing that I can think of is that something is leaking around the mass-air meter. Thats in the fenderwell because of the AFM power pipe, and I don't have my lug nut key to get the wheel off and look in there. But I looked through the hole in the fenderwell and everything looked normal.

Anyone have any suggestions or ideas? This thing is running really rough and doesn't sound good.
 

91LX_5L

Founding Member
May 13, 2002
1,943
0
36
British Columbia
Apr 13, 2005
#2
  • Apr 13, 2005
  • #2
clean iac. check tps.
 

mo_dingo

20+ Year Stangneter
Aug 26, 2003
3,031
2
58
Tucson, AZ
Apr 13, 2005
#3
  • Apr 13, 2005
  • #3
Get a vacuum gauge and check vacuum. Check your fuel pressure w & w/o vacuum. Check your plugs/wires/cap/rotor. Check initial timing.

That's a good start.
Scott
 

zenboy99

Founding Member
May 12, 2002
2,212
0
47
Madison, WI
Apr 14, 2005
#4
  • Apr 14, 2005
  • #4
I cleaned the IAC with carereutor cleaner, timing, plugs, wires and cap are all in working order. I'll check the TPS tonight and go buy a vacuum gauge.
 
You must log in or register to reply here.

Similar threads

K
Resolved Need some assistance. Holley Terminator X alongside H/C/I. Very rough/inconsistent idle
  • karhoot
  • Jun 6, 2026
  • Fox 5.0 Mustang Tech
Replies
0
Views
215
Fox 5.0 Mustang Tech Jun 6, 2026
karhoot
K
A
Rough idle - cylinder 1 and 6 misfire HELP
  • austindavies935
  • Jul 24, 2025
  • SN95 4.6L Mustang Tech
Replies
12
Views
865
SN95 4.6L Mustang Tech Jul 24, 2025
gkomo
T
Help with a 95 5L crank no start
  • TheBubbaJoe
  • Nov 4, 2025
  • 1994 - 1995 Specific Tech
Replies
3
Views
560
1994 - 1995 Specific Tech Nov 5, 2025
AeroCoupe
R
94’ SN95 - Intermittent lope & bogging at moderate rpm
  • Red5.0ho
  • Nov 2, 2025
  • 1994 - 1995 Specific Tech
Replies
5
Views
582
1994 - 1995 Specific Tech Nov 3, 2025
General karthief
F
Fox 1990 Mustang GT 5.0 A9L – Engine suddenly shuts off but immediately restarts when key turned
  • FishermansFriend
  • Aug 9, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
16
Views
657
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Aug 30, 2026
General karthief
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 1994 - 1995 Specific 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?