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Thread: LMM Engine Reduced Power Mode

  1. #1
    Tuner in Training
    Join Date
    Sep 2006
    Posts
    19

    LMM Engine Reduced Power Mode

    So after around 3 years of dealing with ERPM and searching and never really finding a complete answer and thinking the problem was fixed when it was just intermittent, I came across a Thread the other day from Wildman stating that EFI live has a boost error table that HP Tuners does not have to offset the boost error "or the difference in desired boost and actual boost". What they were saying the issue is, is the MAF and the desired boost tables run hand in hand and if the one is too much different than the other it will cause the ERPM, so in order for us, "HP TUNERS" guys to fix the issue you can go in and,

    1-Change the desired boost tables to what you are actually showing on a boost gauge or reading during a scan, or in my case it was my race tune and I knew I was not achieving my desired boost levels. "this is how I fixed mine initially"
    2-Changed my Boost Max table, in my case I had mine at 400kpa as I wanted as much boost as I could get "NOT RECOMENDED" I then changed it to 320kpa instead of changing all of my desired boost tables as it will not desire over 320kpa now and this is a much faster way of doing it.
    3-Rescaling the MAF to fool it into thinking it was getting as much air as you was desiring in your desired boost tables, "I have not tried this option as I am not terribly familiar with rescaling or changing my MAF and I was able to fix the problem with the other 2 options.

    Hopefully this will help someone, and there could possibly be a thread on this already but whenever I searched I couldn't find anything!
    Happy Tuning and Happy Holidays

  2. #2
    Tuner
    Join Date
    Mar 2009
    Location
    Kokomo,In
    Posts
    54
    Post your tune and ill look at it in when i return Monday
    Joe ''House'' Kupferschmid
    Diesel Tuning man..
    FB me or
    www.angoladavesdiesel.com

  3. #3
    Tuner in Training
    Join Date
    Sep 2006
    Posts
    19
    My engine reduce power mode has not come on since making these changes.. I posted this to hopefully help some others that have had the same issues. I know that there is more than one reason for these trucks to go into ERPM however this is the one thing that was triggering mine.

  4. #4
    Potential Tuner
    Join Date
    Mar 2019
    Posts
    2
    So I understand this is an old thread, but in light of my recent discovery while encountering the ERPM on my own LMM after switching from EFI live to HP tuners...I wanted to share my findings in order to help anybody else with an issue if they have it but the previous boost table related post does not solve it.

    Back story on my truck is 2008 Chevy 2500HD 6.6 LMM duramax, When I bought the truck it had EFI live on it, DSP5 tunes from a reputable company, and the autocal was in the console, I playedaround with the autocal after downloading the EFI live software for awhile learking about tuning but the DSP5 tune was locked of course, understandable. Anyways the truck had its emissions equipment removed for "off road reasons" so when I bought HP tuners to delve deeper into knowledge of improving calibrations not only for duramaxes but for cummins, LS, coyote, etc.

    So my research led me to several different observations about the "off road removal of emissions products" with HP Tuners, after getting it and reading my ecm (after I changed back to a stock file and os from efi live) To my understanding from playing with the tune, I figured if i went into the DTC tab and disabled all fault codes related to my missing emissions equipment, that all would be well and I wouldn't have to worry about any fault codes.

    The tunes seemed to work fine for awhile with no DTC's or ERPM. But about a week ago,i started getting ERPM after changing to a different HPT calibration, I had assumed I had did something wrong, so I reflashed back to the calibration I had previously had good luck with and no ERPM, after driving for awhile longer, I got the ERPM again, odd, re-flashed to a different previously working tune. Same thing, I always logged my drives for future improvements so i checked DTCs with the scanner, nothing. No fault codes but ERPM, Flashed EFI Live back to the truck and no problems. Flashed back HPT again, and ERPM, tried several calibration modifications all week but all with the same result, ERPM.

    I had researched several forum posts including this one, all of them had ideas of MAP/MAF/ECM/ or table problems,such as this post. Until tonight I was considering ECM failure, and dependent on other peoples experiences, I might still consider it. At one point I had watched a data log and noticed I had 3 MAP values recording, but they all 3 had different results, about 1 psi separation (i.e 11.5, 12.5, 13.5) So while at work I took the MAP, MAF, and ECM out of the truck and disconnected the batteries on my lunch break. Cleaned the MAP and MAF. Cleaned the ECM contacts, and used dielectric grease on the connector pins of all 3 items, Replaced them in my truck when going home. Re-flashed a tune and logged it while idling, all 3 map values were showing the same now but not long after, ERPM....

    So tonight I was driving home and it did it again, I always have my laptop with me so I checked DTC's again in the scanner and nothing. However, I was about to change to EFI Live again when I remembered I can check the DTC's with EFI scanner. So i started the program and scanned it, no MIL light on dash but ERPM on DIC. EFI Live showed me 6 codes in the ECM.

    P0128 ECT below regulating temp (that has happened before I need to change my thermostats but the code only comes up about every 2 months or so.)
    P0401 EGR flow insufficient
    P0546 EGT Circuit High Bank 1 sensor 1
    P2033 EGT Circuit High Bank 1 sensor 2
    P2455 Particulate Matter trap Diff pressure circuit high
    P2463 DPF soot accumulation

    So I took EFI live scaner back off and reconnected HPT and scanned the DTCs, there were none, all of them were "disabled" in the calibration. Put the EFI back on scanner and cleared the codes, when I hit clear, ERPM went off of the dash, and I had full power again for a short while until down the road, I got ERPM again, cleared codes, no ERPM.

    So after this long story I am confused as to why the calibrations ran fine for awhile and then all the sudden something changed, was it a lower level OS problem I'm running into since HPT doesn't have any Custom OS mods for the LMM? Was it a problem with a previous flash that hurt something in the ECM? Does HPT truly disable the fault codes or only the MIL light for that particular DTC?

    I do apologize for the long post but I am a detailed person and would like to share my experiences with this community as they have shared theirs with me. I am looking for any insight into this problem I am having for I am constantly learning. Hope this ost helps someone who might be having similar issues. Now I'm off to find a solution to my problem.

  5. #5
    HPTuners (alone) cannot fully disable what you are looking to do

  6. #6
    Potential Tuner
    Join Date
    Mar 2019
    Posts
    2
    I see, yes I understand that now. After I posted this I did some more looking around and found out that HPT used to have the parameters for disabling the emissions but from my understanding the parameters dissapeared in one of the updates. I didn't know this when buying the HPT. But, I still plan on using it for other vehicles.