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Thread: Bank1 lean bank 2 ok

  1. #1
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    Bank1 lean bank 2 ok

    What would cause bank1 to be lean and bank2 to be ok?
    Disabled cl, it would still update long term fuel trims, disconnected 02s, and no o2s trims, but bank1 still lean and bank2 is ok, at wot bank2 is 12.20 AFR and bank1 15.8 AFR, both banks same IPW, same VE, is this a mechanical fault?

    its a 2004 TJ, 6.1L engine
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  2. #2
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    I believe you have a Bad O2 censor.. I've seen this before ... the other problem could be a bad catalytic converter. by one or two things , a leak or damage / poor flow .. i think you have two o2 censor in this year , on latter years there are 4 ..

    bank 1 upper
    bank 1 lower
    bank 2 upper
    bank 2 lower

    dont buy the cheap censors, spend the extra 10 dollars and buy the Bosch.. trust me , i have gotten the auto zone cheapies, and i had lots of problems ,, it not auto zone fault.. but i have found from my experience the Bosch has NEVER given me a single problem , neither on my Jeeps, nor on my clubs jeeps ..

    I hope this help you out ..

  3. #3
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    Quote Originally Posted by castorjames View Post
    What would cause bank1 to be lean and bank2 to be ok?
    Disabled cl, it would still update long term fuel trims, disconnected 02s, and no o2s trims, but bank1 still lean and bank2 is ok, at wot bank2 is 12.20 AFR and bank1 15.8 AFR, both banks same IPW, same VE, is this a mechanical fault?

    its a 2004 TJ, 6.1L engine


    OK after reading this a second time , it makes no since ... because if you unplug them both you should be reading different readings .. seem to me it still holding your last readings .. I suggest you unhook you battery for 15 to 20 minutes to zero setting , and them rehook and run test again .. yes i stick to my guns ,,,,, one or both o2s are bad .. or you could have the wrong ones in the wrong location .. bank 1 is different than bank two ????

  4. #4
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    Yes i did, turned off all sensors on tune, disconnected sensors from vehicle, it does not have cats, disconnected battery for some minutes, still same, and WB shows bank1 Lean at wot, and bank2 ok, fuel pressure is good too, let me upload some logs

  5. #5
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    Logs
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  6. #6
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    Possibly a bad injector on Bank 1? Maybe try swapping Bank 1 injectors over to Bank 2 and see if the lean condition follows the injectors.

  7. #7
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    Not saying this is your problem but.. Ive had a car that had new o2 bungs welded in from a shop and they didn't weld all the way around which caused the wide band on that side to read very lean due to the air being scavenged threw the unwelded spot of the bung. Just a thought I chased this issue for a very long time and never found it until i pulled all the exhaust out for new and seen what had been done. Worth a look!!!

  8. #8
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    I did swaped injectors from 1 bank to other, and still same problem, at this point i will check compression, spark plugs, etc etc, but i dont have a clue of whats going on, maybe bad ecm?, it is lean because it kind of cuts like when a car is out of fuel, but its lean only bank 1.

  9. #9
    Intake manifold gasket. Pretty common on older 6.1s

  10. #10
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    hmm, didnt think about it, will check and update..

    What fueling correction pid do we need to use on these ecm? need a custom math?

  11. #11
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    So, the problem was the fuel rails, the hose that connects both fuel rails was clogged. replaced fuel rails and now it is working good, what maths are you guys using for fuel correction?

  12. #12
    Quote Originally Posted by castorjames View Post
    So, the problem was the fuel rails, the hose that connects both fuel rails was clogged. replaced fuel rails and now it is working good, what maths are you guys using for fuel correction?
    Thats new..Will look for that next time.

  13. #13
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    Quote Originally Posted by castorjames View Post
    So, the problem was the fuel rails, the hose that connects both fuel rails was clogged. replaced fuel rails and now it is working good, what maths are you guys using for fuel correction?
    What was the hose clogged with? Couldn't a new hose have solved the problem? If the hose was clogged I would assume what ever was clogging it would have reached your injectors before fully clogging the hose. I would run a few bottles of injector cleaner through you system of the next few tanks of gas to ensure whatever started the clogging doesn't hurt the injectors. As if the clogging is from bad fuel, then your still most likely getting the bad fuel from you local gas station. You really need to find the source of the problem so you don't go through this again.

  14. #14
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    Quote Originally Posted by CannaGeneticsBank View Post
    What was the hose clogged with? Couldn't a new hose have solved the problem? If the hose was clogged I would assume what ever was clogging it would have reached your injectors before fully clogging the hose. I would run a few bottles of injector cleaner through you system of the next few tanks of gas to ensure whatever started the clogging doesn't hurt the injectors. As if the clogging is from bad fuel, then your still most likely getting the bad fuel from you local gas station. You really need to find the source of the problem so you don't go through this again.
    Owner says it was stored for some time, they did the service, spark plugs, oil, new fuel, they took injectors to lab etc.
    There was rust inside the fuel rails, after the injectors where cleaned, all looked ok, but the hose was clogged, at WOT the flow to that side of the fuel rail was lower. Its all good now.

  15. #15
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    Well that sucks. At least every thing is good now.