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Thread: Lean cruise and hpt 2 bar, anyone tried it?

  1. #1
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    Lean cruise and hpt 2 bar, anyone tried it?

    Tuning a turbo 5.3 2001 silverado. Decided to put lean cruise on it. Every time it goes into boost when it comes out and goes back to lean cruise the pcm inverts the subtractor to an adder. AFR goes rich until you go slow enough to kick out of lean cruise, then works correctly again. Anyone tried this before? Solutions?

  2. #2
    AFAIK, all US calibrations have lean cruise disabled in the operating system. This because of emissions (high NOX). HPT doesn't have the ability to turn lean cruise on.
    You can do a open loop tune to achieve similar results

  3. #3
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    Aware of this, this does turn on. Same custom os used on Australian vehicles, was wondering they experience same issue.

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    Fuel Injected! Lextech's Avatar
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    I am not an HPT user---But, doesn't the HPT COS make it a Mafless calibration? If so, I don't think you actually use "Lean Cruise". You would set up your light load Open Loop mixture cells to run at the AFR you choose.

    Jeff
    98 GMC RCSB, 5.0, 4L80e, Moser M60, 4.10 gear, Homemade twin turbo w/Junkyard T3 turbos, 24x CNP, 12200411 PCM.

  5. #5
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    Not sure why you think maf plays in but it works just fine in sd. All lean cruise is is a afr subtractor based on airflow vs rpm once you surpass the enabling speed. I have tested it blended, maf only, sd only and works fine . First hiccup was 2 bar os and becoming an adder after boost.

  6. #6
    Fuel Injected! Lextech's Avatar
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    I guess the point I was actually trying to make is - I'm not sure lean cruise is properly functional in a Custom Operating System.
    98 GMC RCSB, 5.0, 4L80e, Moser M60, 4.10 gear, Homemade twin turbo w/Junkyard T3 turbos, 24x CNP, 12200411 PCM.

  7. #7
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    You would appear to correct on that. Was hoping someone else had tried, maybe on someone with commodore experiance.

  8. #8
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    HPT can enable it...in a cable throttle vehicle. If you try to do it in a DBW vehicle, you seem to lose cruise control...I haven't figured that one out yet.

    To enable it without the OS hack that EFILive does, just change the platform code to V, and move the data from your original platform code over to the V platform in the system options table under engine/system. After that, you need to setup the speed and time delay constants, the EQ ratio subtractor and multiplier, and leanout rate...and don't forget the AFR spark adder...compare to a Holden for an idea of what to do and then tune it from there.

    I did this in my old F-Body (2000 Z28) running a 2002 12212156 OS. I eventually converted that car to the 1 bar enhanced SD OS because of a failed MAF sensor...I saw no need to replace it), and LC still worked fine. I never had any issues with operation of any features of the car with the platform changed to V.

    I have not tried it combined with boost on a 2 or 3 bar OS though.

    I tried the same thing in my 2005 Silverado (12592618 and DBW), and I immediately lost cruise control. Everything else worked, but no cruise control (it did lean cruise though). I wound up doing it with the OS hack in EFILive instead...but I'm not running an enhanced OS in that truck...just the original OS with a minor amount of tuning.
    Last edited by MikeOD; 11-11-2014 at 04:51 PM.

  9. #9
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    I enable lean cruise in .bin format before it goes into hpt. I have modified every o/s from 12212156 to the last p59 available in 2007 including some the efi live patch does not have. Works great. Only problem I have found is when used in conjunction with hpt cos. I want to do some more testing, but have not had access to a vehicle to play with while I had time to play.

  10. #10
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    Quote Originally Posted by mecanicman View Post
    I enable lean cruise in .bin format before it goes into hpt. I have modified every o/s from 12212156 to the last p59 available in 2007 including some the efi live patch does not have. Works great. Only problem I have found is when used in conjunction with hpt cos. I want to do some more testing, but have not had access to a vehicle to play with while I had time to play.
    Are you able to change the VIN# in .BIN form??? Looking for a Lean Cruised version of the 12212156 O/S 2002 350 4L80E Express van calibration. My current setup lacks lean cruise and started life as a 4L60E calibration that has been segment swapped by HPT and simply does not feel right to me. That and I want a 6.0L 4L80E tune for the same VIN for my future EFI Connection 24x swap.

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