I HAVE A 2001 COBRA THAT IS DRIVING ME CRAZY. MY CAR HAS BEEN RUNNING RICH FOR 6 MONTHS. TESTING COMES UP THAT IT IS A O2 SENSOR. I HAVE HAD A SHOP CHANGE THEM OUT AND IT STILL DIDNT FIX THE PROBLEM, SO THE OLD ONES WERE PUT BACK ON. AT FIRST THE CODES SAID THAT THE COILS WERE BAD OR MISFIRING SO I CHANGED OUT THE WHOLE SET. COULD THE PROBLEM BE THAT I PUT A X-PIPE ON AND REMOVED THE CATS? IF SO HOW DO I FIX THIS PROBLEM. THANKS.
COBRA RUNS RICH-HELP
- Thread starter armyhulk1081
- Start date
COBRA90GT
Mustang Master
1st - Welcome aboard to Stangnet. 
2nd - How do you know your car is actually running rich ?
Gonna need answers to a few questions to help you further troubleshoot this...
What kind of shop did you have the car at? Did they get an air-fuel ratio reading for the car? If so, what was the engine's air-fuel ratio across the RPM range? Did they put it on a dyno or anything or how did they datalog the air/fuel ?
If you have already swapped all 8 COPS (coil-on-plugs) and all 4 of your O2 sensors (2 front, 2 rear), you have already thrown quite a few parts (and money) at the problem. I'm guessing you have changed all 8 sparkplugs as well? Were they the correct gap?
Did you or the shop try changing one COP at a time to see if the misfire code "followed" the bad COP around to a different cylinder ?
Also, are you the original owner of the car? What is the complete modification list for the car?
Does the car have a prior custom tune on it or has the factory ECU/computer been re-programmed ? Still have the stock 24lb fuel injectors or are they bigger sized ones (did previous owner run forced induction) ?
FWIW - Swapping to an aftermarket midpipe does not "cause" the engine to run rich - common misconception. Your rear O2 sensors are only there to monitor for the presence of a voltage change (via electronic signal) in the exhaust stream between the front O2 sensors and the rear O2s IIRC.
If catalytic converters are not present, the rear O2s will simply "see" a difference in the electronic signal (via voltage) and trigger a check engine light. The rear O2s are simply a monitoring function.
Now, your front O2 sensors DO communicate with the car's computer/ECU to affect drivability, etc.
Double check everything and get the codes read again and/or try another shop for a 2nd opinion. Most auto parts stores (Autozone, etc) will read check engine/MIL codes for free as well...g'luck !
2nd - How do you know your car is actually running rich ?
Gonna need answers to a few questions to help you further troubleshoot this...What kind of shop did you have the car at? Did they get an air-fuel ratio reading for the car? If so, what was the engine's air-fuel ratio across the RPM range? Did they put it on a dyno or anything or how did they datalog the air/fuel ?
If you have already swapped all 8 COPS (coil-on-plugs) and all 4 of your O2 sensors (2 front, 2 rear), you have already thrown quite a few parts (and money) at the problem. I'm guessing you have changed all 8 sparkplugs as well? Were they the correct gap?
Did you or the shop try changing one COP at a time to see if the misfire code "followed" the bad COP around to a different cylinder ?
Also, are you the original owner of the car? What is the complete modification list for the car?
Does the car have a prior custom tune on it or has the factory ECU/computer been re-programmed ? Still have the stock 24lb fuel injectors or are they bigger sized ones (did previous owner run forced induction) ?
FWIW - Swapping to an aftermarket midpipe does not "cause" the engine to run rich - common misconception. Your rear O2 sensors are only there to monitor for the presence of a voltage change (via electronic signal) in the exhaust stream between the front O2 sensors and the rear O2s IIRC.
If catalytic converters are not present, the rear O2s will simply "see" a difference in the electronic signal (via voltage) and trigger a check engine light. The rear O2s are simply a monitoring function.
Now, your front O2 sensors DO communicate with the car's computer/ECU to affect drivability, etc.
Double check everything and get the codes read again and/or try another shop for a 2nd opinion. Most auto parts stores (Autozone, etc) will read check engine/MIL codes for free as well...g'luck !
So essentially youre running an O/R midpipe then since you removed the cats, as mentioned above you are probably not running rich but your computer is just telling you something is off. I put an O/R xpipe on my v6 and i had the same issue, and my OBDII scanner said it was running rich because of the code it put up, which had to do with the rear o2 sensors, but I installed some 02 simulators and it made the service engine light go away. Do you actually have the rear sensors plugged in still? because a lot of times with aftermarket mid pipes the rear sensors are not long enough to fit, in which case you can buy some extenders on summitracing.com. But any more info you have would help a lot more 
cobra reply
I can tell the car is running rich because you can smell the gas. The milage on the car has also suffered.
I took the car to 2 shops. One shop checked out my mass air and found out everything was fine on the mass air part. The guy designed the intake on the 2010 GT and has a very nice shop, so he knows his stuff. I bought a custon setup from him in which he tuned it for my car. None of this fixed my problem.
I changed the sparkplugs as well with the correct gap. Ive actually changed them 3 times.
I have also put the (cop) in diff places to see if the codes would follow and they didnt. The car actually spit out like 4 diff. codes.
The modifications include. bbk x-pipe, aftermarket cop, bbk twin throttle body, cold air intake and not the cheap jdl kind, underdrive pulleys, flowmasters. Thats all of the engine mods
Also, are you the original owner of the car? What is the complete modification list for the car? Im not the original owner of the car, but the lady who had the car had not driven it in 3 years.
Does the car have a prior custom tune on it or has the factory ECU/computer been re-programmed ? Still have the stock 24lb fuel injectors or are they bigger sized ones (did previous owner run forced induction) ? injectors are stock- nothing has been reprogramed
FWIW - Swapping to an aftermarket midpipe does not "cause" the engine to run rich - common misconception. Your rear O2 sensors are only there to monitor for the presence of a voltage change (via electronic signal) in the exhaust stream between the front O2 sensors and the rear O2s IIRC.
If catalytic converters are not present, the rear O2s will simply "see" a difference in the electronic signal (via voltage) and trigger a check engine light. The rear O2s are simply a monitoring function.
Now, your front O2 sensors DO communicate with the car's computer/ECU to affect drivability, etc.
Double check everything and get the codes read again and/or try another shop for a 2nd opinion. Most auto parts stores (Autozone, etc) will read check engine/MIL codes for free as well...g'luck ![/QUOTE] The code that comes back now says that its in a intake/exhaust pressure- the guy said that usually meant o2 sensor bad
I can tell the car is running rich because you can smell the gas. The milage on the car has also suffered.
I took the car to 2 shops. One shop checked out my mass air and found out everything was fine on the mass air part. The guy designed the intake on the 2010 GT and has a very nice shop, so he knows his stuff. I bought a custon setup from him in which he tuned it for my car. None of this fixed my problem.
I changed the sparkplugs as well with the correct gap. Ive actually changed them 3 times.
I have also put the (cop) in diff places to see if the codes would follow and they didnt. The car actually spit out like 4 diff. codes.
The modifications include. bbk x-pipe, aftermarket cop, bbk twin throttle body, cold air intake and not the cheap jdl kind, underdrive pulleys, flowmasters. Thats all of the engine mods
Also, are you the original owner of the car? What is the complete modification list for the car? Im not the original owner of the car, but the lady who had the car had not driven it in 3 years.
Does the car have a prior custom tune on it or has the factory ECU/computer been re-programmed ? Still have the stock 24lb fuel injectors or are they bigger sized ones (did previous owner run forced induction) ? injectors are stock- nothing has been reprogramed
FWIW - Swapping to an aftermarket midpipe does not "cause" the engine to run rich - common misconception. Your rear O2 sensors are only there to monitor for the presence of a voltage change (via electronic signal) in the exhaust stream between the front O2 sensors and the rear O2s IIRC.
If catalytic converters are not present, the rear O2s will simply "see" a difference in the electronic signal (via voltage) and trigger a check engine light. The rear O2s are simply a monitoring function.
Now, your front O2 sensors DO communicate with the car's computer/ECU to affect drivability, etc.
Double check everything and get the codes read again and/or try another shop for a 2nd opinion. Most auto parts stores (Autozone, etc) will read check engine/MIL codes for free as well...g'luck ![/QUOTE] The code that comes back now says that its in a intake/exhaust pressure- the guy said that usually meant o2 sensor bad
So essentially youre running an O/R midpipe then since you removed the cats, as mentioned above you are probably not running rich but your computer is just telling you something is off. I put an O/R xpipe on my v6 and i had the same issue, and my OBDII scanner said it was running rich because of the code it put up, which had to do with the rear o2 sensors, but I installed some 02 simulators and it made the service engine light go away. Do you actually have the rear sensors plugged in still? because a lot of times with aftermarket mid pipes the rear sensors are not long enough to fit, in which case you can buy some extenders on summitracing.com. But any more info you have would help a lot more
yes the rear sensors are plugged in and barely fit. The car has a hard time staying cranked sometimes, and the exhaust reeks of gas. A slight white smoke also comes out during acceleration and a sut is all over the bottom of the engine.
Mystic1350
Member
check to see if your front Oxygen sensor wires are criss-crossed...I did a bunch of exhaust work and I didnt route them the right way when reassembling which threw everything off/codes/ran rich/etc.
just a quick thing to chizeckkk
just a quick thing to chizeckkk
Similar threads
