NefMoto

Hi, I am trying to understand what would cause this inconsistent running condition.

Background, this is a B5 S4, M-Box ECU - compound turbo setup with blow-thru MAF, 1300cc injectors. The car was tuned Jan-2023 and ran well. I only drove the car 1000 miles or so last year. This spring I have been dealing with the car intermittently running lean at idle and part throttle. WOT fueling seems ok, but transient response gets real rich when the car runs lean (probably because the ECU is trying to compensate with STFTs). LTFTs are not active.

I have not boost leaks, fuel pressure has been verified under all conditions (idle, part throttle, WOT), cleaned my MAF.

After reviewing some logs of when the car ran well vs. running lean (both logs taken last week), I am seeing an offset in actual load vs. request load in the lean running condition at idle, part throttle and WOT. Logs attached. The good running log is v31_141_10, and the lean log is v31_141_20.1.

I see from the FR the RL is calculated from the intake manifold model.
nyet's decode of RL from the FR:

rl = rfges - rfagr
    rfagr = rfges * (250 hPa)/ps (MAF path)
    rfges = pbr - pirg * fupsrl (MAF path)
        pirg = Lowpass(pirgro) * fho (internal residual gas AGR)
            pirgro = (select a prg based on sumod)
                from PRGNM, PRGSUNM, PRG2SUNM, PRG3SUNM (dependent on rpm)
            fho = (correction factor based on ambient pressure)
        fupsrl = Lowpass(psrlro) * ftbr
            psrlro = (select a url based on sumod)
                from URLM, URLSUNM, URL2SUNM, URL3SUNM (dependent on rpm)
            ftbr = (correction based on modeled combustion chamber temp)
                from CWTEMPK, FAKTABGM, FWFTBRTA, FWLKFTBR
                    (dependent on ps, tmot, tans, etc).
        pbr = ps * fpbrkds (MAF path)
            fpbrkds = KFPBRK -> KFPBRKNW (based on fnwue - cam position fader)
    ps = psfg+psagr (MAF path)
        psfg =  sum (0->psmx-(250 hPa)) (rlroh-rlw)*fvisrm
            fvisrm = KISRM * ftsr * 10.13
                ftsr = (tsges + 273)/273
                    tsges = tans (SY_TFA=false) (?IAT downstream of EGR?)

rlroh = rlfgroh (MAF path)
    rlfgroh =
        if (B_dk & B_lm) RLNOT (88->21 for rpm 480->2000)
        if (B_negldrg | E_lkvdk | (SY_EGFE, !B_hfm, etc) rlfdkroh (speed density)
        if (B_mxrlroh) rlfdkroh/fkmsdk (lambts < 1, rldkofk-rlflmroh > DDRLDKZU)
            rlfdkroh = (mste+msdk)/(nmot*KUMSRL)
                mste = (tank ventilation airmass in intake)
                msdk = (air flow over throttle plate)
            fkmsdk = integral(fkmsdkg)
        rlflmroh (MAF path)
            rlflmroh = (mshfms+mste)/(nmot*KUMSRL) - drllad (MAF path)
                drllad =
                    if (B_edsl) 0
                        B_edsl = pvdkds>PVDKMX (dependent on rpm)
                    else pvdkds-lowpass(pvdkds) * KVLAD

http://nefariousmotorsports.com/forum/index.php?topic=617.msg9452#msg9452


However, I don't have most these variables in my logger config file.
Any thoughts on next steps here would be greatly appreciated!!

check maf readings, dirty maf measures less at idle probably

Load is calculated and then multiplied by the factor in KFKHFM (load and rpm), so my issue is before the Maf measurement in the fueling calculations. But I did clean my maf too just to rule that out. The logs show similar injector pulse widths, but the throttle is open more in the lean condition because of the actual vs. requested load error (from what it looks like). I’m hoping some one can help me understand what could cause actual load not too much requested load so I can continue troubleshooting. The FR refers to RLROH as the raw value from the load sensor, is the load sensor the map sensor pre throttle?