I'm curious about how the ECM fires the injector banks on a batch fire setup. Does it fire both banks simultaneously once per cam revolution when a distributor reference pulse is received, or does it use another method?

The reason I'm asking is I'm having a custom cam ground and am considering changing the firing order, so I'd need to know if I have to play doctor with the injector wiring.

 

No change to the injector wiring required. Will need to swap the spark plug wires for those same cylinders that match the new cam firing order.

The TPI set ups are batch fire, all 8 fire together at the same time. Usually once every revolution (double fire). Not sure if the '85 ECM does it, but the '86 - '92 TPI ECMs (code base actually) will switch to single fire on short injector PW.

That is, all eight fire together once every two engine revolutions, with the PW having been doubled.

RBob.

 

Is this true of the TBI ecms also? I thought I read somewhere on these forums that the TBI injectors fire alternately, one injector for a revolution and then the other injector on the next revolution (crank revolution).

 

Good to know. I am running an EBL flash unit btw

 

Cool, it is also a batch fire set up. With the Single Fire (S/F) mode being implemented with the V2.2 release of the ECM firmware (May of 2010).

RBob.

 

TBI ECMs fire each injector alternately on each plug firing. So on an 8-cylinder each injector fires twice per revolution.

RBob.