What does BLM represent? I have a 1989 Chev K1500 350 with a 1227747 ASDU computer. I have both the TunerPro Rt program and the WIN ALDL program. I am trying to find out why my engine will not run correctly when the alternator is charging? I can unplug the single signal wire to the alternator and the engine will smooth out. When the wire is plugged in the motor will go down when accelerating and continues to surge. The tuner program shows a fault [in red] 155 BLM long term fuel trim? When running at less than 12V the number is 128 BLM. If I stay in the throttle long enough the INT fuel trim will go red also? Any help will be appreciated. Thanks G.S.
Please don't take this the wrong way because this appears to be your first post. There are many here more than willing to help, but perhaps you should first do some searching regarding what BLM represents as well as the effect of/reason for/need of the alternator signal wire. There are thousands of posts regarding each on this and other forums. That research may not answer your questions, but it may serve to refine them and will ensure that replies to your questions will make sense. In short, the ECM makes adjustments for battery or pump voltage to the injectors (depends on how the calibration is set-default likely the pump). But way too many variables at this point to speculate. Do some research and come back.