Hello everyone,

After I swapped my l98TPi 1991 for a new 383 custom SBC and modified some parameters in the bin file accordingly I've noticed there is a problem with the ECM. Recently I wrote an S-AUJP v4 bin file but the same symptoms. I've been tuning the VE and spark advance and the car runs relatively well, a few minor adjustments are needed but that's a different story. The problems since I've swapped the engine are:
  • Radiator Fans won't turn on (I have manual switches that ground the ECM wires to turn them on -manual switch turns them on) when requested by the processor (I see that in Tuner Pro),
  • they don't turn on in case of a SYS error either (I had a bad EPROM that caused that, before the swap the ECM worked fine after replacing this same EPROM, so I don;t think this caused the failure; there were random SYS errors, initially I thought it was a bad connection of the pins)
  • digital coolant temperature reading on HVAC does not go higher than 91C although in the Tuner Pro I see it rising and about 10C lower
  • MPG on the dash is pegged at 2l/100km
  • RPM vs idle speed seems to follow HVAC CTS information, basically it goes to set temp for 91C instead of a different RMP in relation to the TUNER PRO data.

Possible cause: The battery went dead while connected to the car, it read 0.9V when I checked it, so maybe the voltage stayed too much at a critical low voltage.
My plan was to buy a spare ECM and see how that works, but it hasn't arrived yet.
Has anyone gone through such problem?