firechicken1992

So looking on the Oriellys website for ECMs, the V6 MPI computer has the same code (01227730) as the V8 MPI/TPI, and same part number. So my question is, knowing there is no crk sensor, are the injector banks fired by dist. pickup? I'm just trying to understand how this ECM works as a whole.

RBob

iTrader: (1)

Yes, the ECM counts the distributor reference pulses (DRPs) to know when to fire the injectors. All injectors are wired to the one driver in the ECM and fire together (batch mode).

It is the MEMCAL that is different between a V6 and a V8 application. Note that the '7730 was also used with a single 1-bbl TBI set up on 4 cylinder engines.

RBob.

firechicken1992

OK. So the MEMCAL is what counts pickups between the V8 and the V6? I saw it behind the small cover thats held on by two screws. I dont plan on doing anything crazy, I just wasnt sure how it varied between the two.

RBob

iTrader: (1)

The MEMCAL sets the DRP count rate. This is done via resisters setting a voltage level that the ECM interprets. The counter is in the ECM hardware, not the MEMCAL.

Note that the distributor is the crank position sensor.

RBob.

firechicken1992

So the MEMCAL makes the ECM decide which values to use essentially? By changing voltage input to the ECM? So does that all use the same counter just at a different rate?

RBob

iTrader: (1)

Yes, there are four choices, port injection for a 8, 6, or 4 cylinder. Then 4 cylinder TBI.

I can't say for sure as this function is internal to custom GM chips. But from past experience in these matters the odds are the same counter is used. Just reset back to 0 after a different number of counts.

RBob.