I'm thinking about trying to use a '7747 to run a 1bbl throttle body on a 4-cyl. Since the injectors are just grounded through the ECM, can the two injector driver leads from the ECM be tied together to drive a single injector? Can just one of the injector drivers be used and just leave the other one unconnected? or maybe substitute a resistor/inductor to simulate the load of an injector? Susposedly the '7747 can be used on a 4-cyl, but I don't know of any 4-cyl applications off the top of my head.

 

Tying the two injectors driver leads together can be done. Just using one driver can also be done. No need to load the unused driver.

If the two drivers are tied together to the single injector be aware that at 50% DC that one injector is really at 100% DC. This is still a viable setup as there is twice the amount of time between firings as a V8.

If only one driver is used then the one injector will fire every other spark plug firing. This would work, but would not properly fuel all cyllinders.

The '7747 hasn't been used for a stock GM 4 cyl TBI app. GM used the '730 in those cases.

RBob.

 

Thanks.... tying the two drivers together sounds like the ticket. I wasn't sure but I couldn't see why it would hurt anything.

Good advice pointed out on the DC, but I had already come to the same conclusion that stated. At 50% DC (from the ECM) the injector is really seeing 100% DC, but since the 100% DC (at the ECM) for a 4-cyl = 50% DC (at the ECM) for an 8-cyl. So, it is well within the injectors abilitly and shouldn't present a problem.

My other option would be to just go ahead and use a 2bbl TB on it. GM put 2bbl TBs on the 2.8L so I would think it would work ok on 3.2L 4-cyl.