Full rich on bank 2 and full lean on bank 1

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  1. #1

    Default Full rich on bank 2 and full lean on bank 1

    Havingan issue with my 98 cobra, Iíve been chasing it since I bought it. When firstpurchased, it had a p0171 code lean bank one. We checked for vacuum leaks, replaced IM gaskets, etcdid all the grunt work. O2s voltage were good.

    Itook it to the first tuning shop, who after a month apparently fixed it andtuned it. Apparently that O2 was faulty. I get it back and it startedbackfiring on the way home. It still backfires some only in the mornings or ifit sits for around 12 hours. Just recently it started dying on me when I pullinto work in the morning also and It smells like itís running fat. Now itíspulling codes for bank 2 being rich, the egr, and a code saying the pcm wasunable to finish its diagnostic test. I figured it was their tune. When Icalled to see why all of these codes were up and why it was running like this Inever got a call back.

    So Itook it to the second shop powercurvemotorsports. Excellent dude! However when he was logging he noticed that bankone is full lean and bank two is full rich. He said my maf was readingcorrectly. He had an identical cobra same year as mine there and he showed methe dyno for it against mine and Iím down about 50hp and 60torquecomparatively. It feels as tho the engine has a dead miss, however no codesfor it.

    Hasanyone had this issue where one side is full rich and the other is full lean?If so what did you do to fix it??

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  3. #2

    Default

    The ECU reads oxygen in the exhaust off the O2 sensor and based on that reading adjusts fueling to bring the mix to whatever the tuner commanded in the tune. If the mix does not get there then the O2 sensor is bad or the problem lies with the injectors. If it is the injectors then you either have a wiring problem or an ECU problem. It is improbable a whole bank of injectors would fail at the same time. You should hope for a wiring problem. Ford no longer offers the ECU.


    Ed
    Last edited by eschaider; 05-27-2020 at 06:47 PM. Reason: spelling and Grammar

  4. #3

    Default Reversed Front O2 Sensor wires

    Quote Originally Posted by Garrett View Post
    Havingan issue with my 98 cobra, Iíve been chasing it since I bought it. When firstpurchased, it had a p0171 code lean bank one. We checked for vacuum leaks, replaced IM gaskets, etcdid all the grunt work. O2s voltage were good.

    Itook it to the first tuning shop, who after a month apparently fixed it andtuned it. Apparently that O2 was faulty. I get it back and it startedbackfiring on the way home. It still backfires some only in the mornings or ifit sits for around 12 hours. Just recently it started dying on me when I pullinto work in the morning also and It smells like itís running fat. Now itíspulling codes for bank 2 being rich, the egr, and a code saying the pcm wasunable to finish its diagnostic test. I figured it was their tune. When Icalled to see why all of these codes were up and why it was running like this Inever got a call back.

    So Itook it to the second shop powercurvemotorsports. Excellent dude! However when he was logging he noticed that bankone is full lean and bank two is full rich. He said my maf was readingcorrectly. He had an identical cobra same year as mine there and he showed methe dyno for it against mine and Iím down about 50hp and 60torquecomparatively. It feels as tho the engine has a dead miss, however no codesfor it.

    Hasanyone had this issue where one side is full rich and the other is full lean?If so what did you do to fix it??
    Yes, I would check the Front O2 sensor wires to see if they are reversed. Common mistake when taking out engine or transmission. One sensor reads lean, so the computer works to rich it out, then the opposite bank gets the fuel, which then wants to lean out. crazy.

    - - - Updated - - -

    The wire diagram is in the Chiltons Repair Manual.

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  6. #4

    Default Fuel Open Loop?

    What do your fuel trims show? I also had my car tuned by Powercurve. My Cobra now shuts off fuel trims and goes to open loop. I suspect that the tune Forces open loop but he says otherwise. Any thoughts there?

  7. #5

    Default

    You can force open loop in the tune which might be what your tuner did. Other than disconnecting the sensor I think the switch to force open loop is the only way to ignore fuel trims.

    Ignoring fuel trims is a good way to hurt the engine. When you do ignore the trims the ECU can no longer adjust fueling in real time to accommodate unforeseen changes in the engine's appetite for fuel. The inability to see or accommodate those changes is a good place to avoid ó it is the origin of many bad experiences and wounded engines.


    Ed

  8. #6

    Default

    Quote Originally Posted by eschaider View Post
    You can force open loop in the tune which might be what your tuner did. Other than disconnecting the sensor I think the switch to force open loop is the only way to ignore fuel trims.

    Ignoring fuel trims is a good way to hurt the engine. When you do ignore the trims the ECU can no longer adjust fueling in real time to accommodate unforeseen changes in the engine's appetite for fuel. The inability to see or accommodate those changes is a good place to avoid ó it is the origin of many bad experiences and wounded engines.


    Ed
    Thanks for that advice. I'm running out of tuners here in Charlotte. I'll have to have it looked at again by someone willing to take the time to actually tune a car vs loading a canned tune.

  9. #7
    Senior Member Array cobraracer46's Avatar
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    Default

    In my view, it was a mistake to take the car to a tuning shop as its been my experience that "tuners" more often than not are unable to properly diagnose and repair drivability issues. Many times, a "tuning" shop will make issue even worse and you mentioned that the car started to back fire and set rich codes after the car was released from the tuner shop thus proving my point about the incompetence of the tuners in general.

    If I were you, I would reload the factory calibration back into the PCM and use a factory MAF sensor and go from there. By the way, It is very rare for O2 sensors and injectors to cause rich or lean codes. The usual suspects for lean rich codes, backfiring issues are vac leaks, bad MAF, bad MAF transfer function or a "tuner" allowed to do stupid stuff with the PCM, ETC.

  10. #8

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    Quote Originally Posted by RedBarron View Post
    Thanks for that advice. I'm running out of tuners here in Charlotte. I'll have to have it looked at again by someone willing to take the time to actually tune a car vs loading a canned tune.

    While Jan's (Cobraracer46) assessment of the tuning community has more than a bit of a negative tinge to it, the point he is try ing to make is none the less a valid one.

    In any field of endeavor there are a wide range of providers form very good to very bad. As the level of training and professionalism increases it will minimize the number of poor quality service providers and accentuate the number of good service providers. Frequently but not always the court of public opinion will offer valuable cues in terms of who the best and worst might be. That still leaves a rather large selection of good but not great service providers to choose from. Many of those will be local to you. All this is to say, you are still in a buyer be ware situation so as the Knight's Templar admonished Indy in the Indiana Jones Movie, The Last Crusade, 'choose wisely!'

    Price alone is not necessarily a good indicator of the best or worst service provider. A combination of time in business offering the service, and certainly community reputation are good indicators of where the service provider falls on the scale of good to bad. The selection process is neither easy nor quick. It can tax you heavily and demand careful investigatory efforts and skills on your part. I have never known anyone who purchased the best to complain about quality or efficacy. I have known many who did not, that did.

    Do your best to choose wisely and also try not to cut corners in the interest of saving a few dollars. The best service providers will likely not be in close proximity to you. It's just the way the cards sort out. Take your time searching, be diligent and thorough, do your best not to price shop but don't allow yourself to get ripped off. The search will be both tough and demanding. Commit and dedicate yourself to the effort. You will be happier in the end.



    Ed

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