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Thread: Wideband went nuts

  1. #1
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    Wideband went nuts

    I have a 99 Suburban that I put a 6.0 into. I got it running initially with the Stock fuel pump but couldn't get more that 40psi outta it. I replaced the pump with a larger one (quantum 340lph) and started it up. everything was logging good until i blipped the throttle pretty good then the Wideband went to super lean and maxed out on the gauge. I know its not lean bc I can smell the unburnt fuel. What would cause that? Maybe an exhaust leak opened up? Is there any way to read the o2 sensors voltage to see if they match the wideband at lean?

    11-14 new fuelk pump.hpl

  2. #2
    Tuning Addict 5FDP's Avatar
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    Not when you are in open loop. The o2 sensors are useless in open loop.

    If closed loop is enabled again you can watch what the sensors do and watch the fuel trims.

    That is a fairly large fuel pump, double check that you aren't getting too much fuel pressure. Often times people need an aftermarket regulator because the stock regulator on the fuel rail won't handle it.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  3. #3
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    I am running a holly fpr. I have it set for 60 psi at the rail. I?m going to try and get under it tonight and see if I see any obvious leaks.

  4. #4
    I'd be tempted to think that your WB sensor is bad. I have a AEM 30-4110 and it eats sensors - when they go bad they usually go full lean. To test it, take it out or the exhaust but leave it connected to the harness. Wrap the sensor in a rag soaked in brake cleaner - if it still shown full lean, the sensor is bad.
    55 Belair swapped 2000 LQ4, 4L80E, 873 cast iron heads have been swapped for 853's, truck manifolds, 2 1/2 inch exhaust, glass pack mufflers, no cats.

  5. #5
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    So I went and tested the Wideband. I turn the truck to accessory and it rests on 14.7 for a few moments then moves to full lean. I soaked a rag in Starting fluid and wrapped the sensor in that and it dropped to 12.0 so it seems to be responding properly. I checked all my band clamps on the Y-pipe and they were all tight. Check the header bolts and they were all tight. When I initially started the truck I had scaled my injector flow rate in the tune assuming I had 60psi of pressure. It was showing lean then and I rescaled the injectors and it was showing rich like I was expecting since I added 15% to the VE table. When I started it today it was showing rich until I revved it up to around 4000. then it pegged lean. Not sure what would have caused that except for an exhaust leak.

  6. #6
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    Are you letting your wideband warm up? Also ive heard of being so rich it could actually read lean

  7. #7
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    I just thought of something, not sure if it could effect it. I saw my Fuel pressure regulator i have mounted right before my fuel rails was leaking a little bit (very small drip) could it be pulling air in when running and causing a lean condition?

  8. #8
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    So here are some updates on this problem, I really need to figure this out since it is completely stopping me from being able to tune this vehicle. AEM is telling me that their gauges were bad. I called them and they said that's a bad gauge. They next day'ed me a new one and I installed it and same effect. Called them back and they said it was probably a bad second gauge. Now they next day'ed me another one and boom 3 in a row same story. Its got to be something in my setup I would thing. I have the gauge ground run off the pin 41 on the red connector, and the white 5v output from the wideband to the egr pin 55 on blue. power is wired to my switched fuseblock i set up for the power wiring diagram. Here are the links to the first startup where its reading correctly and then after a few minutes when it starts reading lean then pegs out lean. My O2 mv are steady in the 900's throughout all this, telling me that the trucks not running rich. can anyone check my work, tune, and look at these videos and see if anything sticks out that could be causing it? Attached are my logs and tune file as well.
    https://youtu.be/dKT3qkcS6Pc
    https://youtu.be/XUNerIZv7Bg
    Attached Files Attached Files
    Last edited by AndrewJReynolds85; 2 Weeks Ago at 04:47 PM.

  9. #9
    Tuning Addict 5FDP's Avatar
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    So the wideband and what the wideband reads in the HP Tuners is still different?

    Or the both are reading the same and going wonky? If it's the first one I'd try a different ground for the wideband, just go to an engine ground instead.

    You never posted your tune either, so something could be wrong with how you have the tune setup. Like if it's open loop MAF or VE.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  10. #10
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    my fault it was acting weird on my. I have added the attachments now. The gauge sends data to the pcm and is showing crazy lean.

  11. #11
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    Bumping to see if anyone had a chance to look at the tunes?

  12. #12
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    Well I got it figured out and it was my own fault. I used the wide band style clamps on my y pipe and one of them was leaking really bad.

  13. #13
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    isn't that amazing customer service from AEM!! holy cow man

    I was just coming to tell you pressure test everything

    fill the plumbing from intake filter side all the way through turbo to the engine.
    And you can perform a similar test by filling from the exhaust side to check some of the exhaust unions.

    a video for pressure testing I made real quick to explain by doing
    https://www.youtube.com/watch?v=rYZmZqn3-x0


    Eventually you caught this leak. However in the future a leak on the intake side when not using a maf sensor is invisible, and kinetic energy is lost which means ineffiency, in turbo applications it means higher IAT higher EGT more exhaust gas pressure and increases sensitivity to detonation or threshold of detonation or whatvever

  14. #14
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    Aem was amazing. They next day everything to me. I finally figured it out by pulling my y-pipe and throwing rubber Gloves over all the ends and pressure testing it. I was for sure it was my weld on the bung but it was the dang bang clamp.