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

okay this is a weird one...

  • Thread starter Thread starter Shirley
  • Start date Start date Oct 29, 2005
S

Shirley

Founding Member
Nov 14, 2001
112
0
0
Phoenix, AZ
Oct 29, 2005
#1
  • Oct 29, 2005
  • #1
The past 2 days, whenever I just start my car or when the turn signals are operating the tach needle jumps frm idle to 1500, then idle to 1500. When I am driving or not using the turn signals, everything is normal. What in the hell is the deal with this?
 

BlownFiveLiter

have car, will race....wait, it doesn't run
15 Year Member
Nov 29, 1999
3,133
18
108
Chicagoland
Oct 29, 2005
#2
  • Oct 29, 2005
  • #2
Is it just the tach needle jumping, but not the engine speed increasing? How does your voltage look at the battery and at the alternator? I see you have a relocated battery, how good is your ground, and what size cables did you use? Take a look at all your connections for corrosion, and make sure your grounds are good.
 
S

Shirley

Founding Member
Nov 14, 2001
112
0
0
Phoenix, AZ
Oct 29, 2005
#3
  • Oct 29, 2005
  • #3
batt voltage is steady, yes it is just the needle and no increase in engine speed. I have 4 grounding points, all are good. 1 computer ground, and 3engine and frame grounds.
 

Black1987Stang

Active Member
Aug 22, 2004
1,422
0
37
Jersey Shore
Oct 30, 2005
#4
  • Oct 30, 2005
  • #4
My brothers 84 f250 with a 351W does that too except it goes up to like 3,000 rpms lol My guess is bad ground or a break in a wire and its using the ground from the tach to ground through instead of its own. I dont know
 
J

JB66

New Member
Aug 21, 2004
565
1
0
New York
Oct 30, 2005
#5
  • Oct 30, 2005
  • #5
Try the ground wire to the instrument cluster or the tan/yellow wire that goes to the TFI module. Also, possibly corrosion on the connector.
 
You must log in or register to reply here.

Similar threads

8
Electrical Crank-no start ... no spark ... no injector pulse, was it something I did? (redux)
  • 85gtCOBRA
  • Oct 28, 2025
  • Fox 5.0 Mustang Tech
Replies
2
Views
632
Fox 5.0 Mustang Tech Oct 29, 2025
85gtCOBRA
8
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
524
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Aug 30, 2026
General karthief
8
Engine Rough idle and aggressive sputtering when accelerating
  • 88vertible
  • Aug 13, 2025
  • Fox 5.0 Mustang Tech
Replies
4
Views
1K
Fox 5.0 Mustang Tech Dec 13, 2025
Jarhead67
J
D
1996 gt mustang block temp vs coolant temp
  • Dkuehn
  • May 21, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
1
Views
111
1996 - 2004 SN95 Mustang -General/Talk- May 22, 2026
squeak93
P
Weird Voltage & Oil Pressure Gauges
  • PNN
  • May 22, 2026
  • SN95 V6 Mustang Tech
Replies
0
Views
113
SN95 V6 Mustang Tech May 22, 2026
PNN
P
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?