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

86 SVO bucking and hopping

  • Thread starter Thread starter cmozez
  • Start date Start date Sep 28, 2008
C

cmozez

Member
May 3, 2003
450
0
16
Tupelo,Mississippi
Sep 28, 2008
#1
  • Sep 28, 2008
  • #1
I just got my old SVO back but it has a small problem. It runs like crap, it will start and run for about two seconds then die. Once it gets warm it will idle but not smooth. You can rev it up in neutral and it does just fine. When you get it on the road it will do ok until the turbo starts to build or it starts to get under load, the car starts to miss real bad, shift gears and same thing.
The things that my buddy did to fix problem: rebuilt dizzy, replaced idle air motor, replaced tps, replaced plugs, rotor, cap, wires, replaced coolant sensor.
I myself checked the timing belt, the timing is at 10, unplugged knock sensor, TPS is at .94vdc.
Before I start throwing parts and time at this thing I sure could use some advice and direction.
 

Red_LX

I’m not much help unless you’re looking for ****!
Founding Member
Nov 29, 1999
5,896
73
129
Morgantown, WV...where couches meet their doom
Sep 29, 2008
#2
  • Sep 29, 2008
  • #2
Tried a new TFI by any chance?

Also, make sure the VAM is functioning correctly.
 
C

cmozez

Member
May 3, 2003
450
0
16
Tupelo,Mississippi
Sep 29, 2008
#3
  • Sep 29, 2008
  • #3
New TFI and PIP with dizzy rebuild. I have not checked the VAM, how do I go about doing it?
 

Red_LX

I’m not much help unless you’re looking for ****!
Founding Member
Nov 29, 1999
5,896
73
129
Morgantown, WV...where couches meet their doom
Sep 30, 2008
#4
  • Sep 30, 2008
  • #4
Well, honestly, I don't entirely know as I've never checked mine.

I know there is a method of hooking up a voltmeter and then opening the "door" inside the VAM to make sure there aren't any dead spots, but I'm not sure where exactly you attach the voltmeter to.
 
C

cmozez

Member
May 3, 2003
450
0
16
Tupelo,Mississippi
Sep 30, 2008
#5
  • Sep 30, 2008
  • #5
I did some research on it today. It is potentiometer(variable resistor). They put 5vdc on one side of it and the more the door opens, the more of that 5vdc the pot will let through to the computer to give it a number to put to the amont of air going through. Any other ideas of what it may be.
 

stykthyn

I want to measure mine. It doesn't look that tall.
15 Year Member
Jul 6, 2006
5,232
2,652
223
gainesville
Sep 30, 2008
#6
  • Sep 30, 2008
  • #6
vacuum leak?
 
C

cmozez

Member
May 3, 2003
450
0
16
Tupelo,Mississippi
Oct 3, 2008
#7
  • Oct 3, 2008
  • #7
It was the vam. Its still not running real good but its a thousand times better than it was
 

86crazyhorse

New Member
Mar 22, 2006
29
0
0
clackamas Or
Oct 11, 2008
#8
  • Oct 11, 2008
  • #8
headgasket.
 
9

94 Black GT

Member
Mar 31, 2005
71
0
6
Oct 12, 2008
#9
  • Oct 12, 2008
  • #9
also inspect the wires and the connection going to the IAB..common to deteriorate..also try removing the IAB and cleaning it..thats what i did on mine and it started the first time and ran perfect with no bucking
 
C

cmozez

Member
May 3, 2003
450
0
16
Tupelo,Mississippi
Oct 12, 2008
#10
  • Oct 12, 2008
  • #10
IAB???
 
8

8T6 SVO

New Member
Nov 8, 2008
5
0
0
Nov 8, 2008
#11
  • Nov 8, 2008
  • #11
cmozez said:
IAB???
Click to expand...

He means IAC - Idle Air Control

This is the silver device attached to the throttle body.

Sounds like you need to do a complete tune up - plug (correct gap), wires, etc.

Check the Vam hose as well - If the spring inside is gone, the hose will collapse and cause lack of power.

What did you do to the VAM to make it work better?
 

Red_LX

I’m not much help unless you’re looking for ****!
Founding Member
Nov 29, 1999
5,896
73
129
Morgantown, WV...where couches meet their doom
Nov 10, 2008
#12
  • Nov 10, 2008
  • #12
Really, it can be either IAC or IAB (Idle Air Bypass), I've seen it written both ways.
 
C

cmozez

Member
May 3, 2003
450
0
16
Tupelo,Mississippi
Nov 11, 2008
#13
  • Nov 11, 2008
  • #13
Did a complete tune up, that all was in first post. I put a meter on the VAM and noticed that the wiper on the pot would jump from 90ohms to 260ohms in one small space. I just bought a new one, BAM, problem almost solved. I have it torn down right now fixing some other stuff I found that probably was the other little bit of issue.
 
You must log in or register to reply here.

Similar threads

7
Engine Random hanging idle
  • 706 Saleen
  • Feb 11, 2026
  • Fox 5.0 Mustang Tech
Replies
9
Views
632
Fox 5.0 Mustang Tech Feb 19, 2026
86HO5.0
8
R
93 LX 2.3 Trouble codes 53, 85, 21 help
  • Rickshaw302
  • Apr 15, 2025
  • 2.3L (N/A & Turbo) Tech
Replies
17
Views
581
2.3L (N/A & Turbo) Tech Apr 18, 2025
AeroCoupe
T
Help with a 95 5L crank no start
  • TheBubbaJoe
  • Nov 4, 2025
  • 1994 - 1995 Specific Tech
Replies
3
Views
440
1994 - 1995 Specific Tech Nov 5, 2025
AeroCoupe
A
Check Engine codes jumping around
  • azactor
  • Jan 9, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
1
Views
182
1996 - 2004 SN95 Mustang -General/Talk- Jan 10, 2026
gkomo
S
Fuel ‘88 GT Runs Rich Cold — Fixes Itself When I Unplug Sensors (ECT, MAF, O2, etc.)
  • Sufarry
  • Nov 6, 2025
  • Fox 5.0 Mustang Tech
Replies
12
Views
825
Fox 5.0 Mustang Tech Nov 9, 2025
Mustang5L5
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2.3L (N/A & Turbo) 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?