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

What should The fuel pressure be set at?

  • Thread starter Thread starter ShortThrow50
  • Start date Start date Apr 10, 2007

ShortThrow50

Member
Oct 22, 2006
923
2
16
Pa
Apr 10, 2007
#1
  • Apr 10, 2007
  • #1
When installing the trick flow top end street heat kit, what should i set the fuel pressure at for a starting point? I plan on getting a bbk fuel pressure regulator and fuel gauge. I want to be on the safe side and not run lean .Im not there yet but I soon will be because Im still painting and cleaning. Hey, im a neat freak. Went through the trouble to pull engine and trans and i dont want to put dirty crap back in the engine bay. Thanks fellas
 
8

86bluecobra

Advanced Member
Dec 20, 2004
4,265
12
69
B.C. Canada
Apr 10, 2007
#2
  • Apr 10, 2007
  • #2
well set it to 40psi. No way you will be lean with that setting.
 

cobradvm

New Member
Sep 2, 2003
245
1
0
Woodinville, WA
Apr 11, 2007
#3
  • Apr 11, 2007
  • #3
39-40 psi is fine as a starting point. But the reality is that it doesn't really matter what you set your fuel pressure at. Once your car goes into closed loop and reads the O2 sensors it will adjust the pulse width of your injectors to get the A/F to where it thinks it should be - will it be lean or rich? Who knows - you will need to get a wideband to tell you that. Once the computer adapts, when you go WOT, it goes to the tables it stored when in closed loop, so what ever it is doing in closed loop will have a similar effect at WOT. If you bump up the fuel pressure, the computer will shorten the injector pulses and vice versa if you drop it. So set it where ever you want to, it doesnt' really matter!
 

jtfairlane

New Member
Mar 5, 2006
468
3
0
Apr 11, 2007
#4
  • Apr 11, 2007
  • #4
The above ^ is kind of true, and kind of not true. The computer can only adjust the injector pulse if the fuel pressure is set within a certain range. If its really rich or really lean, the computer cant adjust the pulse enough to get it to idle/run correctly. Otherwise he's right.
 

ShortThrow50

Member
Oct 22, 2006
923
2
16
Pa
Apr 11, 2007
#5
  • Apr 11, 2007
  • #5
eh. I was afraid of this. Id rather not take my car to get dyno tuned. What are my options? What is the wideband thing? Some sort of programmer. Please explain. I know car engines and such but not the computer part. Thanks
 

vristang

15 Year Member
Mar 31, 2005
4,933
101
124
Seattle
Apr 11, 2007
#6
  • Apr 11, 2007
  • #6
A wideband O2 is an oxygen sensor that is more accurate than the stocker.
Stock O2's are narrow band. An aftermarket wideband O2 will set you back at least $200, depending on options. Most will include some form of datalogging, and the ability to simulate the narrow band signal.

A narrow band O2 is only accurate in a 'narrow' range, which happens to be near stoich. Effectively the narrow band O2 is a switch type sensor. It can only tell the computer that the exhaust is either Rich or Lean; not how far rich or lean though.

A wide band O2 is accurate over a very large range. More than you are likely to use.

The Adaptive Strategy of the EEC-IV can adapt within a range of +/- 12.5%.
Once you peg out of that range, there is no further adaptation to the injector pulsewidths.

jason
 

ls1beater4eva

New Member
May 13, 2005
334
0
0
mooresville
Apr 11, 2007
#7
  • Apr 11, 2007
  • #7
pro pruducts intake??

ok well a friend of mine baught the propruducts intake for his car and the screen that goes under the pcv grommet falls strait to the bottom of the baffel has anybody else had this prob with this intake ?
 

ShortThrow50

Member
Oct 22, 2006
923
2
16
Pa
Apr 12, 2007
#8
  • Apr 12, 2007
  • #8
vristang said:
A wideband O2 is an oxygen sensor that is more accurate than the stocker.
Stock O2's are narrow band. An aftermarket wideband O2 will set you back at least $200, depending on options. Most will include some form of datalogging, and the ability to simulate the narrow band signal.

A narrow band O2 is only accurate in a 'narrow' range, which happens to be near stoich. Effectively the narrow band O2 is a switch type sensor. It can only tell the computer that the exhaust is either Rich or Lean; not how far rich or lean though.

A wide band O2 is accurate over a very large range. More than you are likely to use.

The Adaptive Strategy of the EEC-IV can adapt within a range of +/- 12.5%.
Once you peg out of that range, there is no further adaptation to the injector pulsewidths.

jason
Click to expand...
So would one of these be beneficial for a top end job? Or should i hold off till the day i do something bigger such as a stroker?
 

Flavadave4

Active Member
Nov 28, 2003
1,044
21
49
Utica, NY
Apr 12, 2007
#9
  • Apr 12, 2007
  • #9
start at 40psi with the vac off.
 

ShortThrow50

Member
Oct 22, 2006
923
2
16
Pa
Apr 12, 2007
#10
  • Apr 12, 2007
  • #10
Flavadave4 said:
start at 40psi with the vac off.
Click to expand...

With the vac disconneted? Ok. Ill do that. Gotta love this site for all the fox owners. I would be up ****s creek without you guys. Thanks
 

ronburgundy

Member
Nov 19, 2006
179
0
16
BC coast
Apr 12, 2007
#11
  • Apr 12, 2007
  • #11
i have the aeromotive press. reg. it said to start at 48 psi static(no vaccuum). mine seems to run fine with the tf top end and 24 squirters.
 
You must log in or register to reply here.

Similar threads

D
Fuel Erratic Fuel Pressure 1985 GT
  • DienstXIV
  • Jan 14, 2026
  • Fox 5.0 Mustang Tech
Replies
16
Views
680
Fox 5.0 Mustang Tech Jan 16, 2026
AeroCoupe
Fox Xtremely high fuel consumption
  • PonyGTrider
  • Apr 11, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 9 10 11
Replies
213
Views
4K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- May 9, 2026
PonyGTrider
Engine 1990 LX 5.0L EFI Mustang Fuel Management Problems - HELP!
  • 5.0LXStanger
  • May 25, 2025
  • Fox 5.0 Mustang Tech
  • 2 3
Replies
45
Views
2K
Fox 5.0 Mustang Tech Jul 11, 2025
5.0LXStanger
A
Resolved Fuel pressure high at 52 new FPR same thing
  • afjLX
  • Dec 28, 2024
  • Fox 5.0 Mustang Tech
  • 3 4 5
Replies
90
Views
4K
Fox 5.0 Mustang Tech Jan 11, 2025
AeroCoupe
B
'03 GT Fuel Pump/Pressure/Delivery Issue
  • Brodach
  • Oct 21, 2025
  • SN95 4.6L Mustang Tech
Replies
8
Views
911
SN95 4.6L Mustang Tech Oct 31, 2025
gkomo
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?