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Thread: First GenIV LMG swap AFM data logs

  1. #41
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    The only VSS I have is on the trans output shaft and mine shifts the same regardless of TC gear.

    Ther'es a few things you can do in the lean cruise area to get it to stay in V4 mode longer.

    Raise your TPS max% - I believe GM set it at 6%, raise it to 20%.
    Raise your TPS HYST - I believe GM set it at .5%, raise it to 3%

    Then you can change your enable/disable vacuum thresholds to suit.

    I'm not getting 28 mpg, but I'm getting better than you are with my 6,000lb Jeep Wrangler. Conversion is still too new and I only have freeway data while pulling my camper trailer and I was getting around 14 mpg @ 75 mph. I would assume without that bigger brick back there it would be higher than 14...? My Edge controller says I'm getting around 22-26 mpg through town. I didn't have it with me on my trip to Moab last month to know how accurate it is...

  2. #42
    Senior Member PSWired's Avatar
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    Where is this TPS hysteresis calibration value? I can only find the TPS upper cutoff value in my OS...
    1995 GMC Yukon 4WD 4DR
    5.3 "LMG" engine: E85 with AFM
    6L80e 6 speed automatic transmission

  3. #43
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    Quote Originally Posted by PSWired View Post
    Where is this TPS hysteresis calibration value? I can only find the TPS upper cutoff value in my OS...
    It might only be a value the other guys use - I don't have EFILive.

  4. #44
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    Thanks for the TPS info waynehartwig. I have AFM staying active most of the time now.
    You mention lean cruise which I have been trying to achive with mixed results. As other threads indicate the USA E-38 is not lean cruise friendly. My old EBL ECU went open loop under cruise and picking an AFR was simple, not so with my E38.
    I had the pleasure to meet Harold recently and we discussed the E38's desire to run at stoich or richer.
    I performed Swingtens Auto VE and too my surprise my stock VE Map was not far off. Most annoying though is IM running about 14:2-14:3 AFR in most cells closed loop. I've sucsessfully modified DFCO to stay in till about 1000 rpm which helped mpg. Most of this is trial and error at best but here is what I have tried to lean out cruise:
    Lowered MAF frequency-seemed to make a very small change, but the LTFT increased and the end result was nothing.
    Changed the stoich setting to 15.3-result nothing.
    Changed o2 switching point to as low as 200mv-nothing.
    Added an EFIE(O2 signal modifier). The first one I tried was digital which switched from .1-.9v and the switch point was adjustable-had no effect. Tried a analog EFIE which piggyback's a few hundred mv to the O2 signal and I got some results, however the LTFT's again seemed to fight back.
    As of today I lowered the MAF frequency and am running the EFIE and am able the keep most VE cells about 14:7 as read through my wideband. It's not a solution though, I believe the E38 is too rational. In a steady state cruise all seems fine at 14:7 +; although, when it switches between AFM and V8 mode there is a flat spot and sometimes it will throw a P0106 MAP performance code and go into some kind of limp mode and the O2's stop switching. Once it threw an AFR irrationally code. If I lower the piggyback voltage the codes stay away but the results are neglagible. I believe the E38 cross checks different inputs and knows where it should be and ignores what it feels isn't correct.
    All this and my VE map averages 14:7, not worth it. I would expect in stock tune the VE would be closer to stoich, and 15-16:1 lean cruise is just not there.
    PS waynehartwig you have out done me. One of my plasitic leaf springs cracked so I reinstalled the steel ones(an xtra 200lbs:(
    Also I believe my Dashdaq readout was off regarding milage. After several thousand miles of fill ups, calculating gallons/miles, I am averaging 26.7 mpg. With the EFIE and the MAF Hz mod my hwy mpg is over 30, but driveabily suffers. We need an open loop lean cruise for the E-38(N0x aside), maybe add an EGR?
    PSS Running open loop the world is wonderful, obtaining 15:1 + at cruise is easy. This is my next trial, although losing CL I think is too high of a price to pay, and there will be a lot of WB monitoring for saftey. I know there is a few more mpg to be had. I understand the lean cruise issue and why the real smart guys don't assist us with it which would make it simple. Im running and old truck mostly off road so I'll keep trying.

  5. #45
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    F350 running gear, V8 swap, 1/4" thick steel plate panels, bumpers, roll cage, etc. add up!

    P0106 is because the MAP min/max values are incorrect. Look at your tune and see if there are tables dedicated to V4 and V8 mode. Maybe when V8 mode kicks in, the MAP is skyrocketing causing the code. Maybe simply raising the max value will stop the code from showing up? I just know you don't want to disable the code. It's actually a good thing to have.

    Understand what I'm saying? In case you need to know how V4 mode works.

    When signaled, the ECM shoots one more shot of fuel in all of the cylinders, then disables the valves from moving, keeping that charge in there. Even though the valves no longer operate, the cylinders still fire. Then when the time limit in V4 mode is exhausted, the exhaust valve opens, pushing the spent charge out and then moves to V8 mode and all is normal.

    So maybe it's just too close?

    Lean cruise is doable, as I mine does it. I run around 14.8-15.1 while going down the freeway. I wish you could see my tune. It might help.

  6. #46
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    Default Lean Cruise

    Yes there is a dramatic increase in MAP kpa when AFM kicks in; certainly the OE ECM takes this into account when transitioning into LC.

    What software are you using to calibrate? How are you maintaining 15:1 in CL? I would be interested to see your tune; perhaps some parameters are similar to EFI LIve.

  7. #47
    Senior Member PSWired's Avatar
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    While on the subject of MAP codes, if anyone here manages to update their 2007 ECM with a 2008 or 2009 OS without bricking it, be aware you will need to replace your MAP sensor with the new part for 2008+
    1995 GMC Yukon 4WD 4DR
    5.3 "LMG" engine: E85 with AFM
    6L80e 6 speed automatic transmission

  8. #48
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    Quote Originally Posted by VEGASROBBI View Post
    Yes there is a dramatic increase in MAP kpa when AFM kicks in; certainly the OE ECM takes this into account when transitioning into LC.

    What software are you using to calibrate? How are you maintaining 15:1 in CL? I would be interested to see your tune; perhaps some parameters are similar to EFI LIve.
    I use HPTuners.

    It doesn't maintain 15.1, it varies between 14.8 and 15.1 - according to my wideband that I run constantly. Maybe yours does as well if checked with a wideband? I need to fatten mine up, though, because while a lean cruise is ok most of the time, it's not ok when pulling a trailer. If I was to run it a bit fatter, I could control my engine/oil temps better. It's all because of the super small radiator I have to run in the Wrangler, then it's also blocked by a big winch to boot.

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