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Thread: Newbie questions about L67 3800 tuning

  1. #1
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    Newbie questions about L67 3800 tuning

    Hi guys,
    I have just started dipping my toes into tuning on my 2005 Monte Carlo SS with the 3.8L SC L67 engine. I have been reading and watching videos, and tonight I went and did a scan for LTFT+STFT tuning. I don't have my wideband installed yet, so as of now I am just trying to tune idle and low throttle fuel trims. I went ahead and disconnected my MAF sensor, however I didn't disable PE as advised by Goat Rope Garage and a few others. I have uploaded my log file below.

    first drive 1-4-2020 original tune.hpl

    The first thing that stands out to me is my LTFT+STFT table is waaayyy off, assuming I have it set up correctly of course. My understanding is that I now need to multiply by half those values into my Primary VE vs. RPM vs. MAP table and then do it all again, is that correct? Is there anything else I should do? Did I do something wrong with my table or something?

  2. #2
    Tuning Addict 5FDP's Avatar
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    If you want my opinion, tuning the VE is not really worth the time on a 3800. It's a MAF based operating system.

    I never once tuned the VE when I had my 2000 Grand Prix with a 3.6 pulley, intake, headers etc. Can't even remember anyone really specificly tuning the VE years ago when I owned that car. If you plug the MAF back in I bet all the trims go back to normal.

    Add more data to your logs for the future tuning. Thing like commanded AFR, knock retard, your primary O2 sensor, injector pulse width avg for both banks, cylinder airmass.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  3. #3
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    Quote Originally Posted by 5FDP View Post
    If you want my opinion, tuning the VE is not really worth the time on a 3800. It's a MAF based operating system.

    I never once tuned the VE when I had my 2000 Grand Prix with a 3.6 pulley, intake, headers etc. Can't even remember anyone really specificly tuning the VE years ago when I owned that car. If you plug the MAF back in I bet all the trims go back to normal.

    Add more data to your logs for the future tuning. Thing like commanded AFR, knock retard, your primary O2 sensor, injector pulse width avg for both banks, cylinder airmass.
    Gotcha, I'll have to go plug that back in and check it. As for the more data, this is what data I have it set up to log when its not plugged into the car
    log.PNG

    But, as you can probably see from the log in the OP, a lot of that stuff disappears when I actually scan. Why is that? For example, I clearly have Knock Retard selected as a PID I want to log, but my log doesn't actually have it when I go and open it. When I got the car dyno tuned a few months ago (which is why I am tuning this myself now), the guy mentioned he couldn't read KR, I wonder if its the same problem I have with KR not being logged for me?

  4. #4
    Tuning Addict 5FDP's Avatar
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    You need to add those channels while connected to the vehicle. So go to the car, connect the scanner, click vehicle and repoll for supported parameters. Then add the channels you want to log, they all should start showing up then.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

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    Quote Originally Posted by 5FDP View Post
    You need to add those channels while connected to the vehicle. So go to the car, connect the scanner, click vehicle and repoll for supported parameters. Then add the channels you want to log, they all should start showing up then.
    Just did a repoll, all the channels in the screenshot above stayed there. They don't disappear until I hit the record button.

  6. #6
    Tuning Addict 5FDP's Avatar
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    Did you remove them, then re-add them?

    If not, do that and see what happens.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

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    I deleted KR, connected the MPVI2, repolled and then readded KR. Still disappears when I hit record.

  8. #8
    Tuning Addict 5FDP's Avatar
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    Beats me. Never run into that issue before. Repolling for supported channels and adding it back in while connected to the vehicle has always worked for me.

    May have to contact support directly to have them figure it out.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  9. #9
    Advanced Tuner ZeroBoostBuick's Avatar
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    I tuned a handful of 3800 cars and the VE table only made a difference on my 98 Regal. All other cars were 2000+ and the VE tuning didn't matter.

  10. #10
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    Quote Originally Posted by Keudn View Post
    I deleted KR, connected the MPVI2, repolled and then readded KR. Still disappears when I hit record.
    Inbox me your email address and I can send you my config files (Channels, Graphs, etc)...
    Daily Driver= 1998 Pontiac Grand Prix GTP Coupe (3.4 pulley, SD Headers, SLP catback, FWI, 180 t-stat, hotwired FP, Autolite 103's, poly dogbone bushings, solid rubber engine and trans mounts, self tuned with HP Tuners)
    Weekend Cruiser= 2009 Pontiac G8 GT (Vararam, TSP LS3 N/A Stage 1, OBX, CTS-V converter, MagnaFlows w/ J-Pipes, 160 t-stat, self tuned with HP Tuners)
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