• Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang Tech

To lean please help

  • Thread starter Thread starter sonic_03gt
  • Start date Start date Apr 2, 2009

sonic_03gt

New Member
Apr 2, 2009
27
0
0
Gas city, Indiana
Apr 2, 2009
#1
  • Apr 2, 2009
  • #1
First off i am a new member. And i absulutely love this site. I have been looking for a forum for a few weeks now. But any ways, My car is coming up to lean on both 02s. And it kinda seems like it wants to rev up and down on its own....Not bad or nothing maybve jumps around 2-300 rpms. Does any one know what would cause this? It runs great while on the gas...My gas mileage seemed to drop real bad tho? My mods are n my sig I am new to the ford world and have always been a camaro guy. Any help would b gretly appreciated. Thnx guys.
 

98COBRA281

10 Year Member
Nov 24, 2007
1,348
30
59
Port St. Lucie, Florida
Apr 2, 2009
#2
  • Apr 2, 2009
  • #2
for some reason you sig is not working, can you post up your mods, and has yuor car been tuned?
 

sonic_03gt

New Member
Apr 2, 2009
27
0
0
Gas city, Indiana
Apr 3, 2009
#3
  • Apr 3, 2009
  • #3
I bought the car with most of the parts all but the wheels springs gears and the shifter. When i got it ran perfect with the mods it had. So i am guessing some kind of tuning has been done. but idk?
slp longtubes
slp o/r x
sp lm1
bbk cai
4:10s
eibach pro kit
steeda ud pulleys
 

RedDaemon

10 Year Member
Mar 31, 2005
3,470
9
108
Atlanta, GA
Apr 3, 2009
#4
  • Apr 3, 2009
  • #4
what octane do you fill up your car with? if its not a cobra, GTs take 87.

if you just filled the car up with a lower octane this could explain why yours running lean.
 

DBMSTNG

I fantasize about it being BIG!
Founding Member
Apr 23, 2002
2,120
0
56
not quite here
Apr 3, 2009
#5
  • Apr 3, 2009
  • #5
is there a K&N filter on the CAI? if so, check the maf to see if there is any filter oil on the sensor. if so, that could be causing the problem.
 

sonic_03gt

New Member
Apr 2, 2009
27
0
0
Gas city, Indiana
Apr 4, 2009
#6
  • Apr 4, 2009
  • #6
I have checked for vaccum leaks and exhaust leaks. Changed the fuel filter and cleaned the maf sensor already. I just dont underst7and why it would b lean like this all at once?
 

GoBabyVroommm

Active Member
Mar 22, 2003
1,156
0
36
Chicago, For Realss???!!!
Apr 4, 2009
#7
  • Apr 4, 2009
  • #7
Well i'm going to say its o2s. If you have a stick car you won't notice bad o2s but if its a auto car it sucks. But then again, if your o2s are out the computer makes your car run very rich so you don't blow your motor.

Another idea is that your pump might be going out. From my understanding that 99-04 pumps work a little harder then the return system pumps.

Just puttin my 2 cent in hope it helps.
 

sonic_03gt

New Member
Apr 2, 2009
27
0
0
Gas city, Indiana
Apr 4, 2009
#8
  • Apr 4, 2009
  • #8
Would both go bad all at once tho?? I mean i guess that kinda makes sense bc of gas mileage.
 
You must log in or register to reply here.

Similar threads

F
Trouble Shooting Sudden Shift of AFR at low RPM
  • Farva_84
  • Jun 6, 2025
  • SN95 4.6L Mustang Tech
Replies
8
Views
430
SN95 4.6L Mustang Tech Jun 8, 2025
Farva_84
F
S
Fox '87 GT can't get to stay running
  • spilly
  • Mar 29, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
26
Views
561
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Apr 25, 2026
CAMTWO1070
A
Please!? I need some help with my 1964.5 alternator conversion
  • Alabear94
  • Dec 6, 2025
  • 1965 - 1973 Classic Mustangs -General/Talk-
Replies
2
Views
280
1965 - 1973 Classic Mustangs -General/Talk- Jan 10, 2026
GOvert
G
Removing speedo cable from the VSS
  • 91AOD5.0LX
  • Mar 25, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
27
Views
680
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Apr 25, 2026
91AOD5.0LX
A
2001 Mustang GT, scorched metal smell and noise from trans/diff?
  • AndyE2255
  • Dec 1, 2025
  • SN95 4.6L Mustang Tech
Replies
4
Views
397
SN95 4.6L Mustang Tech Dec 28, 2025
gkomo
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L 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?