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Thread: 2012 302 lean tipout problem

  1. #1
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    2012 302 lean tipout problem

    *** Begin unnecessarily long backstory ***

    The car I'm working on is a 2012 Boss 302. I bought it with a lot of modifications already done: JLT intake, BBK 85mm TB, Kooks 1-3/4" LT headers, and catless midsection, GT500 mufflers. I had no idea who did the tuning, but it had a bunch of weird drivability issues. First I looked for vacuum/exhaust leaks, and I didn't find any. So I did some remote tuning through an online retailer. After about 5 revisions it was almost as bad as when I started. So I decided to give it a try myself.

    I flashed everything back to stock and then I entered the parameters for the throttle body model that someone had posted on this forum. Then I adjusted the MAF period vs. Air Flow table based on average LTFT + STFT averages. After I did that, the car was running and driving a lot better than it ever had before.

    *** End of backstory ***

    Here's the problem I'm having now: When I let off the pedal, after a few seconds I feel like there's way too much engine braking going on and the AFR sensors go full lean. Someone suggested adjusting the torque based decel settings. So in a previous version (not the one I'm posting) I disabled the torque decel switch. It would do almost exactly the same thing, but then it would stall out when rolling to a stop. Can someone take a look and point me in the right direction?

    Edit: When I roll back on the throttle under about 2k rpm I get a bad pop which I would love to get rid of too.

    FPRD1_V16.hpt
    LogV16.hpl
    Last edited by dtownmikebrown; 09-22-2019 at 08:20 PM.

  2. #2
    Senior Tuner veeefour's Avatar
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    You need to fix your VCT - it hangs in Optimum Power then it transits to Optimal Stability and your OS angles are not the best choice for this setup hence you have so much engine braking.
    Last edited by veeefour; 09-23-2019 at 12:51 AM.

  3. #3
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    I think this is the part where I start to get a little bit out of my depth, so lemme make sure I'm understanding VCT correctly before I ask too many more questions...When the load value drops to 0.13, Optimal Stability mode is triggered. So that means when RPM falls below 4000 it starts going directly from mapped point 7 to mapped point 0, at which point VCT is effectively set to 0 degrees. Correct?

    VCT-1.jpg
    So there's a hierarchy to the VCT modes, right? If I'm in OS mode and I exceed 0.13 load, shouldn't it switch over to Fuel Economy mode? If fuel economy mode is also mapped to point 0 at that load value, will the log still show OS mode until the load increases enough for the mapped point to change? Should I be lowering the load level in the OS max load table, remapping the Optimal Stability table, or both?

  4. #4
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    What yours is doing on deceleration is staying in OP until 4000 RPM beause you have both OP Load/Pedal Position thresholds set to 0. You need to change these. This will also create drivability issues if you were to be driving at highway speeds and your load and pedal exceed their low thresholds. Your car would go into OP at 2000 RPM and would start jerking.
    Your car uses cam angles to control a stable decel and how the car is set up isn't really benefitting your deceleration. They're not optimal Your car is trying to decelerate by using less spark advance and IVO. Theres so much overlap when it's decelerating that you hit tipout limit and the car starts trying to decelerate with your MBT tables. You want the IVO to advance during decel. You don't want the EVC to retard during decel. Change the 7 to a 10 instead, that would help out a lot and probably get rid of your tip-out limit. Populate the Spark Decel table would give you an even better proabability to solve your problem.
    Yes, you're right on how the table works and that is what your car is following.

    The area circled will also give you issues. As load increases the mapped point value should increase. Having them set up similar second picture will give you better drivability, economy, and a better rolling launch.

    BESTFUEleco.PNG
    bestfuelecoadjusted.PNG

  5. #5
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    Thanks for the replies. It put me on the right track. I'm staying out of the tipout limit now that I've made the recommended changes. I think the leaning out was more due to DFCO settings than anything else.

  6. #6
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    the 2012 boss cal is one of the better stock coyote base files for the 11-12s you don't need to go making any significant changes since your basically stock.

    start over with a stock file, put in the jlt maf transfer, kick up the o2 delay and waste your time dialing in the eta table for your throttle body.

    Your car is basically stock is should run like a stock car with no problems at all.

    Once you get the throttle body dialed in and the car is runs show room stock you can then go do as you wish tune wise making changes.
    decipha @ EFIDynoTuning
    http://www.efidynotuning.com/

  7. #7
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    Quote Originally Posted by decipha View Post
    the 2012 boss cal is one of the better stock coyote base files for the 11-12s you don't need to go making any significant changes since your basically stock.

    start over with a stock file, put in the jlt maf transfer, kick up the o2 delay and waste your time dialing in the eta table for your throttle body.

    Your car is basically stock is should run like a stock car with no problems at all.

    Once you get the throttle body dialed in and the car is runs show room stock you can then go do as you wish tune wise making changes.
    I'm at a disadvantage here because I've never driven a showroom stock Boss 302, or any other Coyote Mustang for that matter. I'm hoping I can rely on data logs to figure out how close I am to getting it right.

    The ETC Angle/Effective Area tables I found were supposedly directly from the TB manufacturer. Isn't it better to stick with a known value? I'm not so sure about the MAF values. I found two identical transfer table values from different sources that are supposedly for my JLT intake, but I'm not sure either of them are all that accurate when looking at ST and LT fuel trims.

    Load values at Mapped Point 0 under normal driving conditions seem like they should be a lot lower.

    Capture.PNG

    That also seems to be right around the range where I have a lot of IPC errors occurring.

    Capture2.PNG

    Is it more likely here that my MAF transfer values are off, or that I need to readjust my torque tables for that mapped point, or both?

  8. #8
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    Hindsight being 20/20, it's obvious why the lambda reading was going lean. Deceleration fuel cutoff was enabled. The loud pop rolling on the throttle was "catalyst reactivation" dumping extra fuel for the nonexistent catalytic converters. Seems obvious now why there would be a loud afterfire every time.

    As for the drivability issues I was having, decipha was absolutely right. Get the MAF and ETC values right and it will drive very nicely on an otherwise stock calibration. I pulled a throttle body from a junkyard F150, ditched the 85mm throttle body and never looked back. For the MAF, I emailed JLT support and much to my surprise someone replied quickly with the correct inputs for the model CAI-FMG-11. I believe the data that had originally been entered was for a CAI-FMG2-11. The stuff I came up with myself wasn't too far off compared to what JLT supplied me with.

    Evidently it's not a bad idea to clean and re-oil the filter once every decade or so, whether it needs it or not. That helped too. I think there's a reason JLT discontinued the first version of their cold air intake and redesigned it, and it probably wasn't some foolhardy attempt to improve on perfection. The MAF sensor on version 1 was all the way up at the front end of the intake tube right behind the filter. That just doesn't seem to be a great place for it. I'm no expert in fluid dynamics, but I feel like there's a reason why so many cone filter intakes from other manufacturers (along with JLT's version 2) place the MAF sensor a bit further downstream.