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

For Those Who Care

  • Thread starter Thread starter OhNo- 5-0
  • Start date Start date Mar 9, 2016
  • Tags Tags
    fmu fuel management unit hesitation paxton rough running sputtering supercharged
O

OhNo- 5-0

New Member
Jul 26, 2013
1
0
1
Mar 9, 2016
#1
  • Mar 9, 2016
  • #1
For those who care to take a guess at the issue or have seen this issue before!-

As warmer weather nears, I'll be fiddling with the car to get more info. Here are the specs/ concerns:

-88 original 5.0 car Paxton novi 1000 supercharged with FMU
- (No chip in ECU)
-Car is still speed density

Issue: After reaching NOT, the car sputters at maybe 2300rpm-3000 rpm (sounds almost like fuel cut) . Before and after those rpms, car has good power and runs fine

Again, if anyone feels confident they have a good test for me to do before I begin to do the diagnostics, your knowledge would be greatly appreciated!!
 

jrichker

StangNet's favorite TOOL
In Remembrance. Thank you for your contributions
Mar 10, 2000
27,512
2,813
234
Dublin GA
Mar 10, 2016
#2
  • Mar 10, 2016
  • #2
Dump codes sticky.

Look at the top of the 5.0 Tech forum where the sticky threads are posted. One of them is how to dump the computer codes. I highly suggest that you read it and follow the instructions to dump the codes.
 

7991LXnSHO

wanna catch the space herp
10 Year Member
Sep 1, 2010
7,387
2,745
194
Kearney, NE
Mar 11, 2016
#3
  • Mar 11, 2016
  • #3
Can you even run a speed density with a supercharger? That seems likely to exceed the stock computer's programming if changing c/h/I will.
 

coupestang2

Active Member
Sep 11, 2014
108
132
53
Cornelius NC
Mar 13, 2016
#4
  • Mar 13, 2016
  • #4
7991LXnSHO said:
Can you even run a speed density with a supercharger? That seems likely to exceed the stock computer's programming if changing c/h/I will.
Click to expand...
Yes...with a stand alone system like megasquirt, Accel, Holley..etc.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,236
17,921
224
Massachusetts
Mar 14, 2016
#5
  • Mar 14, 2016
  • #5
Step #1, run the codes


But, gonna go out on a limb here and guess that a supercharged setup on a stock SD system might be part of the reason. I'd run the codes first, aside from anything else obviously wrong, I'd suggest a Mass Air conversion to start
 

7991LXnSHO

wanna catch the space herp
10 Year Member
Sep 1, 2010
7,387
2,745
194
Kearney, NE
Mar 14, 2016
#6
  • Mar 14, 2016
  • #6
Yep, that's exactly what I was thinking. Unless he left something important off the list...

But we'll hopefully hear the codes.
 
You must log in or register to reply here.

Similar threads

G
Sputtering/misfiring below 2500rpm
  • Godless
  • Sep 14, 2025
  • 2005 - 2014 S-197 Mustang -General/Talk-
Replies
5
Views
384
2005 - 2014 S-197 Mustang -General/Talk- Sep 14, 2025
gkomo
B
'03 GT Fuel Pump/Pressure/Delivery Issue
  • Brodach
  • Oct 21, 2025
  • SN95 4.6L Mustang Tech
Replies
8
Views
876
SN95 4.6L Mustang Tech Oct 31, 2025
gkomo
Engine '93 running rough, especially at low rpm's and idle.
  • evintho
  • Oct 19, 2019
  • Fox 5.0 Mustang Tech
Replies
1
Views
4K
Fox 5.0 Mustang Tech Oct 19, 2019
jrichker
J
93 mustang breaking up during acceleration
  • JDiFet
  • Dec 12, 2019
  • 2.3L (N/A & Turbo) Tech
Replies
11
Views
6K
2.3L (N/A & Turbo) Tech Dec 24, 2019
1993TripleWhiteFox
1
P
Info for 05-09 Mustang GT owners who have experienced total power loss (dead stalls) after 1-2 hours of hwy driving
  • purplegold90
  • Oct 31, 2019
  • 2005 - 2014 S-197 Mustang -General/Talk-
Replies
1
Views
3K
2005 - 2014 S-197 Mustang -General/Talk- Nov 1, 2019
racerraj
R
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?