a/f ratio goin crazy

[306Stang]

my car isn't a cobra but i don't know where else to post this.

about 3-4 days ago i got in the car, started it up, and started driving. i always keep an eye on the guages and i noticed the a/f wasn't right. first off when i turned the car on and let it warm up a bit the meter was reading that the a/f ratio was pegged out at rich. so i start driving it and when i give it about 3/4 throttle it feels like the car is bogging and getting starved for fuel. while i do this the meter is going crazy. as in the meter is reading that it is lean all the way through stoich. and through rich as well. if i barely give it gas the car acts fine but the meter is still going crazy.

i bought this car at the end of jan. and all the mods were done by the previous owner. i've sent him a message on a local forum but he has not replied. the car has driven perfectly untill now and i have a chip that has been burned from JMSCHIP in the mail to me.

mods related are :

Engine: DSS Pro bullet 306, Edelbrock RPM 1.90 valved heads, FMS e-303 cam, Crane 1.6 RR's, 7 qt canton pan, Trickflow Streetheat Upper/lower, 65 mm T/B, 75 mm Pro-M mass air, 24 lb injectors, smog pump delete,

Drivetrain: Tremec 3550, spec stage 1 clutch, 3.55 gears, 28 spline moser axles, aluminum driveshaft, and steeda clutch quadrant,firewal adjuster, adjustable cable.


Fuel: 255 lph fuel pump, FMS fuel pressure regulator,24 lb injectors

anyone have any clues????????????????????????????????

 

[306Stang]

nobody???

 

[SNSTR_SNK]

is this one of the auto meter a/f guages?

 

[CY98Cobra]

My auto meter a/f guage does the same thing. Dances back and forth until I go WOT, then it goes rich. Don't go by the guage, they aren't accurate.

 

[COBRASVT]

Do you have a check engine light? You probably should, but maybe not yet.

Your a/f guage is a pos...it doesn't actually read the air fuel...it is simply a visual representation of the voltage that the O2 sensor is sending to the pcm.

Sounds like you may have a bad O2. That's where I'd start.

 

[306Stang]

is this one of the auto meter a/f guages?

don't think so but they are Cobalt series gauges, i'll try to find out what they are tomorrow

 

[94CobraPace]

If it is the Cobalt series Auto Meter gauge then it is a narrow band O2. It is a good light show & can only tell the if it is richer or leaner than around 13.9 (not sure on the exact number).

 

[306Stang]

Do you have a check engine light? You probably should, but maybe not yet. <-------------NOPE

Your a/f guage is a pos...it doesn't actually read the air fuel...it is simply a visual representation of the voltage that the O2 sensor is sending to the pcm.

Sounds like you may have a bad O2. That's where I'd start.

looks like i get to go to the parts store

Quote from 94CobraPace:
"If it is the Cobalt series Auto Meter gauge then it is a narrow band O2. It is a good light show & can only tell the if it is richer or leaner than around 13.9 (not sure on the exact number)." <----------------well damn it!!

 

[306Stang]

well it was the o2 sensor. thanx for the hint cobrasvt

 

[Doug]

all cars run a little rich on cold start up. a/f gauges only work at WOT and don't do squat unless you have a wideband o2 sensor