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

idle problems

  • Thread starter Thread starter ja950a
  • Start date Start date Jul 21, 2009
J

ja950a

New Member
Jul 21, 2009
9
0
0
neworleans la.
Jul 21, 2009
#1
  • Jul 21, 2009
  • #1
hi guys i have a 89 mustang 5.0 lx. this is my problem the engine will idle fine until the a/c is turned on or steering is turned. Also the engine don't seem to have any crack to it or responce, but it will climb rpm's.It's a fresh stock longblock with aftermarket: headers, h-pipe,catback,and blaster coil. Any help would be appreciated thanks.
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
34
129
Jul 22, 2009
#2
  • Jul 22, 2009
  • #2
Retarded timing can cause lackluster performance and a low idle.

Idle assistance under load (for the AC) is achieved with the IAC. Yours might be having issues or dirty.
 

jrichker

StangNet's favorite TOOL
In Remembrance. Thank you for your contributions
Mar 10, 2000
27,512
2,813
234
Dublin GA
Jul 22, 2009
#3
  • Jul 22, 2009
  • #3
See the "Surging Idle Checklist for help with all your idle/stall problems. Everything you need to find and fix idle problems is in there.

The first two posts contain all the updates to the fixes. At last count there were 24 possible causes and fixes for surging idle/stall problems. I continue to update it as more people post fixes or ask questions.
 
B

BYRDPE

Founding Member
Nov 4, 1998
1,556
0
37
Memphis,Tn.
Jul 22, 2009
#4
  • Jul 22, 2009
  • #4
yup...verify your timing with a light and the spout out.
 
J

ja950a

New Member
Jul 21, 2009
9
0
0
neworleans la.
Jul 22, 2009
#5
  • Jul 22, 2009
  • #5
thanks for the info.Should I go with the stock timing at 10* btdc because thats where it is now for sure.Also would the iac affect power even with no load from a/c, power steering etc.
 
J

ja950a

New Member
Jul 21, 2009
9
0
0
neworleans la.
Jul 22, 2009
#6
  • Jul 22, 2009
  • #6
I have one other problem the engine don't warm up past about 135* with new 180* thermo,new water pump, and stock radiator.
 
B

BYRDPE

Founding Member
Nov 4, 1998
1,556
0
37
Memphis,Tn.
Jul 22, 2009
#7
  • Jul 22, 2009
  • #7
are you verifying the temps with an aftermarket gauge?
as far as timing i would start ~12 and make a couple of wot pulls and listen for detonation. if there is none go to 14 and test.
 
J

ja950a

New Member
Jul 21, 2009
9
0
0
neworleans la.
Jul 22, 2009
#8
  • Jul 22, 2009
  • #8
yes auto meter mechanical
 
J

ja950a

New Member
Jul 21, 2009
9
0
0
neworleans la.
Jul 22, 2009
#9
  • Jul 22, 2009
  • #9
just noticed your from Tn. i'm from huntington tn.
 
B

BYRDPE

Founding Member
Nov 4, 1998
1,556
0
37
Memphis,Tn.
Jul 22, 2009
#10
  • Jul 22, 2009
  • #10
ja950a said:
just noticed your from Tn. i'm from huntington tn.
Click to expand...

yup...howdy neighbor.
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
34
129
Jul 23, 2009
#11
  • Jul 23, 2009
  • #11
Yes, the IAC affects the idle even with no ancillary loads on the engine.



Confirm the reading on your aftermarket gauge.
 
J

ja950a

New Member
Jul 21, 2009
9
0
0
neworleans la.
Jul 25, 2009
#12
  • Jul 25, 2009
  • #12
I mean would it effect anything besides the idle quality.
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
34
129
Jul 26, 2009
#13
  • Jul 26, 2009
  • #13
ja950a said:
I mean would it effect anything besides the idle quality.
Click to expand...

Not anything meaningful (it affects idle quality, accomodation of load, and a few little things like dashpot). It has no effect on power.
 
J

ja950a

New Member
Jul 21, 2009
9
0
0
neworleans la.
Jul 26, 2009
#14
  • Jul 26, 2009
  • #14
can the charcoal canister be removed or is it nessesary. I did forget to mention that the car has no cats and no smog pump,also has mallory hyfire 4 ignition box.
 
You must log in or register to reply here.

Similar threads

M
Idle problem
  • miser143
  • Oct 9, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
4
Views
187
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Oct 11, 2026
CAMTWO1070
W
1993 LX 5.0 dies after ignition parts replacement
  • Warhorse85
  • Aug 16, 2025
  • Fox 5.0 Mustang Tech
  • 5 6 7
Replies
122
Views
5K
Fox 5.0 Mustang Tech Nov 4, 2025
General karthief
B
Electrical Why does my fox body keep frying eecs
  • brandyn200
  • Jun 20, 2026
  • Fox 5.0 Mustang Tech
Replies
8
Views
498
Fox 5.0 Mustang Tech Jun 25, 2026
AeroCoupe
Engine Random Misfire at idle.
  • Gulftown980x
  • Jul 29, 2026
  • SN95 4.6L Mustang Tech
Replies
11
Views
593
SN95 4.6L Mustang Tech Jul 31, 2026
squeak93
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
661
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-
  • 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?