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  1. #1
    Lifetime Member LB72004's Avatar
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    Default somewhat sluggish at times

    doing some logging to see if i can find out why at times it seems that when i am pushing my truck hard it seems to accelerate to a point then hangs and won't accelerate any more. almost like it is loosing fuel pressure but the log shows good pressure.

    it seems like it is as if it is related to boost or grams/sec air but maybe it is vain position???

    here is a screen shot
    Click image for larger version. 

Name:	Bug log.PNG 
Views:	324 
Size:	62.6 KB 
ID:	17446

    anyone able to see anything obvious?
    2008 Chevrolet 3500HD DRW LTZ
    285/75/17 Nitto Dura Grapplers, 4.56 gears, Front and rear ARB lockers, Efi Live tuning by me, Raptor 160 LP, Cognito 4-6 NTB Lift, 4" Exhaust, Built Trans by Mike L.

    Sold - 2004 LB7 Duramax, EFI Live with DSP5 Tune
    stage 4 SC transmission, 265/70/16 tires

  2. #2
    Lifetime Member LB72004's Avatar
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    Opps, put this in the wrong area. Any administrators able to move this over to the LMM section for me.

    Thanks Jason
    Last edited by LB72004; September 8th, 2014 at 09:12 AM.
    2008 Chevrolet 3500HD DRW LTZ
    285/75/17 Nitto Dura Grapplers, 4.56 gears, Front and rear ARB lockers, Efi Live tuning by me, Raptor 160 LP, Cognito 4-6 NTB Lift, 4" Exhaust, Built Trans by Mike L.

    Sold - 2004 LB7 Duramax, EFI Live with DSP5 Tune
    stage 4 SC transmission, 265/70/16 tires

  3. #3
    Lifetime Member Mitco39's Avatar
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    Where are you having the issues? Just a quick look at the image shows a fairly linear acceleration...

  4. #4
    Lifetime Member LB72004's Avatar
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    if you look at the MPH from about 2770 all the way to 2800 it only increases about 5 MPH. from 2800 to the end it is about a 25 MPH difference. also right at the line you can see the mm3 shoot up. prior to the line you can see that the throttle is held at roughly 90% and the mm3 is slowly dropping. something changes, this is what i am trying to find out, and the fuel increases and the truck starts to accelerate much quicker. about 20 MPH quicker in the same amount of time as before the line on the graph.

    the only thing that i see is that i pull out a little on the throttle just before the fuel jump up, which i would only think it should make it less not more, and of course the bottom of the graph with the grams/sec, vane position & boost.

    i believe my problem lies in what is happening at the bottom of the graph. some sort of limiter or bad vane to boost correlation. you can see that shortly before the line boost starts to rise and gains about 10 PSI. the vanes are slowly opening up then suddenly the grams/sec air starts to climb and bam, the ECM sees the right amount of air and adds more fuel.

    the problem with this is that it is a little smoky before the line on the graph then right at the line when the fuel jumps up the smoke clears up. so there does seem to be a air to fuel ratio problem here but why is the turbo holding back? i am starting to think that i should try and open the vanes up a little in that area of the map and see if it helps. i am wondering if the closed vanes trying to create boost is just choking off the exhaust and hurting air flow
    2008 Chevrolet 3500HD DRW LTZ
    285/75/17 Nitto Dura Grapplers, 4.56 gears, Front and rear ARB lockers, Efi Live tuning by me, Raptor 160 LP, Cognito 4-6 NTB Lift, 4" Exhaust, Built Trans by Mike L.

    Sold - 2004 LB7 Duramax, EFI Live with DSP5 Tune
    stage 4 SC transmission, 265/70/16 tires

  5. #5
    Lifetime Member Mitco39's Avatar
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    So your smokey before the turbo spools? I need to see a actual injection time (in Us) to be able to see what sort of fuel your throwing at it.

    Just looking at it quickly it looks like your MAF may be dirty, thats whats causing you the issues. Or thats where I would start looking anyways. You could have a leak between your MAF and turbo I guess. If its all been modified I would just look around there and see if anything looks out of place. As long as you havent scaled your MAF with some funny adjusters I would believe looking at this log that its a mechanical issue.

  6. #6
    Lifetime Member LB72004's Avatar
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    ok, i will see if i can get my MAF cleaned and run another log for my way home today.

    i thought i had selected the Us pid when i logged it, but maybe not. i will add it to this run

    the intake is all stock. stock filter, stock intake and i haven't changed the MAF scaling.

    one thing i noticed last night when going over the information and looking at the tune is that the tune calls for something like 35% vane position in the area of the log between 2770 to 2800 yet the log shows something like 95+%. and looking over the multipliers, etc I could find nothing that would explain the high vane % in the log. maybe it is jacked up PID control. time to verify that. may also try and zero out some of the multipliers too
    2008 Chevrolet 3500HD DRW LTZ
    285/75/17 Nitto Dura Grapplers, 4.56 gears, Front and rear ARB lockers, Efi Live tuning by me, Raptor 160 LP, Cognito 4-6 NTB Lift, 4" Exhaust, Built Trans by Mike L.

    Sold - 2004 LB7 Duramax, EFI Live with DSP5 Tune
    stage 4 SC transmission, 265/70/16 tires

  7. #7
    Lifetime Member Mitco39's Avatar
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    The turbo is going to do everything in its power to make the request boost that you have set in the boost tables (as long as B2231 and B2232 allow). So if your telling the turbo to build more boost than possible (or if you have a leak bleeding off boost) the turbo is going to ride the Turbo Vane Target Position Maximum to do its best to reach your intended boost.

    Look over your Desired boost level tables and make sure you are not asking to much of the turbo you have.

  8. #8
    Lifetime Member LB72004's Avatar
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    just realized, in order to get an effective turbo brake one would have to modify the B2231 & B2232 tables right?

    back on track, so the boost tables override the vane tables. vane tables are supposed to be a starting point and then the ECM adjusts them based on if the turbo is making the required boost or not. and is is the PID tables that dictate how quickly the ECM makes the adjustments. is this correct?

    so if the ECM is running the low altitude boost table then the boost is pretty close to commanded. if it is running the transient table then i can is 8 or so PSI short and the ecm would want to crank it up some.

    i didn't want to but maybe i need to make my transient and altitude tables the same. then i will have a better understanding on what tables to look at when combing through the logs.

    it seems that most of the time it is running in the transient tables, even during acceleration. is this what others do?
    2008 Chevrolet 3500HD DRW LTZ
    285/75/17 Nitto Dura Grapplers, 4.56 gears, Front and rear ARB lockers, Efi Live tuning by me, Raptor 160 LP, Cognito 4-6 NTB Lift, 4" Exhaust, Built Trans by Mike L.

    Sold - 2004 LB7 Duramax, EFI Live with DSP5 Tune
    stage 4 SC transmission, 265/70/16 tires

  9. #9
    Lifetime Member LB72004's Avatar
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    ok, cleaned the MAF sensor.

    here is another log:
    Click image for larger version. 

Name:	Sluggish.PNG 
Views:	311 
Size:	64.3 KB 
ID:	17455
    same thing happened here. oddly enough it happened at the exact same time as the last log. right when i start to lift off the throttle. hmm new lead???

    here is another screenshot from later in the log where it did what it should. ran strong right from the get go and did not get stuck with declining mm3s and short on boost
    Click image for larger version. 

Name:	Not Sluggish.PNG 
Views:	307 
Size:	60.4 KB 
ID:	17456

    and attached is the full log
    Attached Files Attached Files
    2008 Chevrolet 3500HD DRW LTZ
    285/75/17 Nitto Dura Grapplers, 4.56 gears, Front and rear ARB lockers, Efi Live tuning by me, Raptor 160 LP, Cognito 4-6 NTB Lift, 4" Exhaust, Built Trans by Mike L.

    Sold - 2004 LB7 Duramax, EFI Live with DSP5 Tune
    stage 4 SC transmission, 265/70/16 tires

  10. #10
    Lifetime Member LB72004's Avatar
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    i added my input on these attachments
    Click image for larger version. 

Name:	Sluggish.PNG 
Views:	273 
Size:	73.8 KB 
ID:	17458

    Click image for larger version. 

Name:	Not Sluggish.PNG 
Views:	294 
Size:	65.4 KB 
ID:	17459

    what do you think?
    2008 Chevrolet 3500HD DRW LTZ
    285/75/17 Nitto Dura Grapplers, 4.56 gears, Front and rear ARB lockers, Efi Live tuning by me, Raptor 160 LP, Cognito 4-6 NTB Lift, 4" Exhaust, Built Trans by Mike L.

    Sold - 2004 LB7 Duramax, EFI Live with DSP5 Tune
    stage 4 SC transmission, 265/70/16 tires

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