1991 Mustang LX Smell Fuel in Exhaust, Bogging down

James Sims

New Member
Mar 13, 2004
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1991 Mustang Smell Fuel in Exhaust, Bogging down Code 91 HELP!!

-NEW WATER PUMP
-TIMEING CHAIN
-TFS TRACK HEAT UPPER AND LOWER WITH STAGE 1 PORT
-GT40 HEADS
-SCORPION 1.7 ROCKERS
-24LB INJECTORS
-ADJUSTABLE FUEL REGULATOR
-New Fuel pump 255
-F CAM
-Z RATED 93 COBRA 5 SPEED
-93 COBRA COMPUTER
-70 MM MASS AIR
-THROTTLE BODY
-NEW MOTOR MOUNTS
-BASSANI HEADERS
-BASSANI X PIPE WITH CATS
-NEW STAGE 2 CLUTCH
W/ STEEDA ADJUSTABLE CLUTCH CABLE AND CLUTCH QUADRANT THAT HAD

These are all the mods are the car, I do have a tweecer too that I havnt used just yet.....
I can smell fuel in the exhaust and it falls on its face at 2500rpm I have tried everything need some help! Timing has been checked it sitting at 14.5 or so! help please
 
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ls1beater4eva

New Member
May 13, 2005
334
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mooresville
whats your fp set at? and when u say falls on its face at 2500 is it just like laying over or spitting and popping ? what kind of maf are you running? what kidn of balancer are you useing
 

James Sims

New Member
Mar 13, 2004
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fp set at 39psi and its spitting and popping detonation, my maf is stock from a 93 cobra, what do you mean by balancer? James
 

James Sims

New Member
Mar 13, 2004
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ran the codes last nite

I ran the codes last nite iam getting a 91 which is oxygen sensor problem, fuel pressure out of specified range or injectors out of balance! hmmmm
 

backfocus

Member
Sep 3, 2004
254
2
18
45
Little Rock, AR
Need more info on the computer and the Mass air. The computer is for sure a cobra unit? What is the Mass Air, is it a Cobra unit as well? Just asking since the cobra computer compensates for the injectors in the computer and not the Mass air.
 

2000xp8

SN Certified Technician
Aug 8, 2003
6,659
890
194
NJ
It's probably the o2 sensors.
They are a common problem.

I'd also ditch the cobra computer and meter, in exchange for a stock computer and PMAS meter. Although i doubt they are the problem, but they are certainly a restriction.
 

97vertstang

Member
Aug 17, 2005
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33
fontana ca
Code 41 or 91 - O2 indicates system lean. Look for a vacuum leak or failing O2 sensor.

I also pull 91 new 02 sensors and I know for a fact the car is hella' rich. You happen to run long tube headers?
im having a similar problem, and it happened after i installed my long tube headers. how does it all tie together and whats the problem???
 

ram360

Founding Member
Oct 19, 2002
2,162
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Pennsylvania
superstallion360.tripod.com
im having a similar problem, and it happened after i installed my long tube headers. how does it all tie together and whats the problem???
the 02 sensors are furuther down and they don't heat up. It's telling the computer it's lean and it's adding more fuel that I don't need My 02's are brand new and no vacuum leaks. Keep giving me code 91. I know for a fact the car is not lean whatsoever....in fact it's so rich it's to the point the exhaust burns my eyes. I have a tuner and pull %12 fuel out a idle just to compensate but its' more of a band aid than anything else at this point. I've yet to have someone tell me how to solve the issue...
 

James Sims

New Member
Mar 13, 2004
4
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0
bad injectors

I changed out the injectors last nite! it fixed the problem!!! bad injectors! simple enough! james