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Thread: 2000 GTP Tuning Trouble

  1. #1
    Tuner CTX-SLPR's Avatar
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    2000 GTP Tuning Trouble

    Howdy,

    I've run into a bit of an issue with trying to tune some upgrades to my car. It's basically a Grand National old school Turbo6 run by a 2000 Grand Prix GTP ECM. It was working as well as it could without a turbo while I got the mechanical bugs work out of the car. This meant stock L67 injectors, an L36 timing table, and the LQ4 MAF table off of the repository with a bunch of the trouble codes turned off. I started the car with the new turbo and 55lb/hr injectors and even took it on a short drive around the block on this same tune looking for oil leaks, ect. It will run and idle fine but it's pig rich and giving it anything other than the lightest of touches to the gas will make the ECM pull fuel and it'll lean pop and try to stall. Still good enough to move the car around though.

    I went into the editor (3.6, I had to download it since I'd wiped the laptop since my last tuning years ago which was done on 2.something) and multiplied the injectors straight across by 1.5 and promptly got an error about exceeding the range and if I wanted to override it (which I have done both ways, the number always populates the table either way). I then copied the stock L67 timing tables in and double checked my MAF table to make sure I had the LQ4 table in there. After flashing it I got start but fail to stay running like it's a VATS problem. I tried flashing cal only, complete write, and even complete write slow and nothing has resolved the start but stall. I've double checked that I have P1626, P1629, P1630, and P1631 all set to 3, No Error Reporting as well as logging the VATS status bit and I get a PASS. I've attached the baseline tune (which still run when I reloaded it), the new tune, and the matching logs.

    Thanks for the help in advance,
    Attached Files Attached Files
    Central TEXAS Sleeper
    Experimental Physicist

    Current:
    1964 Riviera (4.1L Buick Turbo6, 4L80E, L67 PCM)
    2012 Hyundai Genesis Sedan (3.8 GDI, 8spd Getrag)
    1998 Chevrolet Suburban K2500 (454, 4L80E)
    SOLD:
    1970 Riviera
    1965 Riviera GS (465 Super Wildcat, SP400) #'s Matching
    1967 Skylark Deluxe
    1997.5 Regal GS

  2. #2
    Tuning Addict 5FDP's Avatar
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    Your MAF curve is whacked.

    Compare it to a stock curve, look at how different your numbers are when you look at lb/min. It can't run when you have numbers in the table that aren't even possible to see, they are so low that the computer could never run a such little airflow.

    Just as an example. On a stock GTP curve at 7,000hz, it will say 11.158 lb/min of airflow. Your table says 0.192 lb/min. Now you'll see why it could never run.

    You copied the wrong information over, or something went wrong when you did.

    I went and found a stock 6.0 file on my computer, copied the MAF curve, pasted the curve and it went back to a stock MAF curve with similar OEM numbers.
    Last edited by 5FDP; 06-29-2017 at 12:00 PM.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  3. #3
    Tuner CTX-SLPR's Avatar
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    So my "double check" of the MAF table has some how corrupted it it sounds like. OK, tonight I'll pull that one again and put it in and see what happens.

    Thanks
    Central TEXAS Sleeper
    Experimental Physicist

    Current:
    1964 Riviera (4.1L Buick Turbo6, 4L80E, L67 PCM)
    2012 Hyundai Genesis Sedan (3.8 GDI, 8spd Getrag)
    1998 Chevrolet Suburban K2500 (454, 4L80E)
    SOLD:
    1970 Riviera
    1965 Riviera GS (465 Super Wildcat, SP400) #'s Matching
    1967 Skylark Deluxe
    1997.5 Regal GS

  4. #4
    Tuner CTX-SLPR's Avatar
    Join Date
    Jan 2008
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    Livermore, CA
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    Put the original MAF table back in and it starts and runs though not great. Now I actually get to tune this thing. Thanks for the help!
    Central TEXAS Sleeper
    Experimental Physicist

    Current:
    1964 Riviera (4.1L Buick Turbo6, 4L80E, L67 PCM)
    2012 Hyundai Genesis Sedan (3.8 GDI, 8spd Getrag)
    1998 Chevrolet Suburban K2500 (454, 4L80E)
    SOLD:
    1970 Riviera
    1965 Riviera GS (465 Super Wildcat, SP400) #'s Matching
    1967 Skylark Deluxe
    1997.5 Regal GS

  5. #5
    Potential Tuner MorisT67's Avatar
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    Jul 2015
    Location
    milwaukee
    Posts
    4
    you know where i cound find a stock maf curve for a LT1 maf?

    2002 GTP
    -PTE6766 turbo
    -Stage 4 turbo cam
    -Double Roller
    -Ported heads
    -Built TEP transmission
    More...More....More...

  6. #6
    Tuner CTX-SLPR's Avatar
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    Jan 2008
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    Livermore, CA
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    Update: It's running better and better as I sort it out. Still having issues with the fact that a 4T65E has a 30 tooth reluctor and a 4L80E has a 40 tooth and that's causing it to throw incorrect gear errors. I've also somehow got it stuck thinking it's in gear (might be the pesky Range A codes that I still need to check the harness on) so it doesn't do so well transitioning from in gear to out of gear.

    I've finally tracked down a stock Grand National timing table and it's way more aggressive than even an L36 table so it's running like crap beyond light load where I had spliced in L36 values. I've got that ready to flash on tomorrow and I richened up the part throttle (up to 7500Hz) by 3% over baseline LQ4 since the wideband is showing an average AFR in the 15.5:1 region.
    Central TEXAS Sleeper
    Experimental Physicist

    Current:
    1964 Riviera (4.1L Buick Turbo6, 4L80E, L67 PCM)
    2012 Hyundai Genesis Sedan (3.8 GDI, 8spd Getrag)
    1998 Chevrolet Suburban K2500 (454, 4L80E)
    SOLD:
    1970 Riviera
    1965 Riviera GS (465 Super Wildcat, SP400) #'s Matching
    1967 Skylark Deluxe
    1997.5 Regal GS