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Thread: wideband inaccurate? or something else wrong?

  1. #1
    Advanced Tuner
    Join Date
    Sep 2010
    Location
    webb city, mo
    Posts
    504

    Question wideband inaccurate? or something else wrong?

    I tuned a 2007 Yukon Denali with the 6.2 this week. The truck was bone stock with the exception of a Comp VVT cam, phase limiter, & springs/pushrods, which is 214/228 .559/.571 114. Stock intake, stock exhaust with cats, stock...air filter and everything.

    I tuned it with my new AFRM wideband. In open loop, was getting 1.00 lambda all across the MAF frequency range with a few 0.99's and 1.01's. Fueling was spot on. I put the truck back in open loop and told the owner to come get it. While i was waiting on him, I took the truck for one last test drive now that it was in closed loop and the front O2 was back in place. LTFTs were -9% in ALL cells after each cell got enough good steady state recordings. STFTs were fluctuating nicely, + or - 3-5%, once the LTFT reached -9%.

    After going over the tune to make sure i didn't miss something, i decided to just multiply the Low and High MAF tables by 0.92 and go for another test drive. This time, LTFT were around +or- 4% in the worst cells, most were 2-3%. That's why i think my wideband is off, or i'm not setting up my scanner correctly. My AFRM function is Volts/5.333 + 0.62. Stoich in the tune is 14.67822. i'm not on my laptop right now so i can't post a log or the tune, but i'm just curious if my wideband is junk or not. It shows to be calibrated correctly when i check it. Any thoughts?

  2. #2
    Advanced Tuner
    Join Date
    Sep 2010
    Location
    webb city, mo
    Posts
    504
    Sort of verified my hunch today. I put the AFRM on the shelf and got my AFX back out. It DID have a bad sensor, so i went to autozone and got a Bosch 15401 for it. I tuned a 2011 SS Camaro today with longtubes and cold air. I calibrated the MAF in open loop and when i put the car back in closed loop, fuel trims were +or- 2%....AFRM will continue to sit on the shelf.