Which ECU

[festy]

Here's the wiring diagrams for both the TBI and MPFI versions of the pulsar/astra if they help at all.

[Apples]

When I did Astra training we were told the D9 and D10 pins were linked to enable both injector drivers to work together / both take the load for TBI only.
never played with it to see what it really did do or could do.
I did read some were that gm did it on other ecm for TBI / low ohm injectors.

[knuts2au]

I thought it would have the other way around, joining 9 & 10 would join 15 &16 together on the output, but then really it should all be software driven. Might have to have a closer look inside and see what's in there. Anyone have a cct diagram for one.
So what is the impedance of the single TBI injector and what is the impedance of the individual MPI injectors?
PeterN

[VK_3800]

Even though there are two output pins, there's only one injector driver on the 808 - that's why its not suitable for V8 TBI, the GM TBI ECUs have two drivers so that the injectors can be alternated when required. Most wiring looms simply join D15 and D16 anyway.

GM low impedance TBI injectors are normally around 1-2ohms if I recall correctly.

[Holden202T]

can you get a driver off another ecm and put it into give you the extra needed or is there more too it than that ?

[VK_3800]

I have no idea but I'm guessing it would be simpler to just get a US TBI ECU with memcal and suitable definition files for Tunerpro, although you wouldn't get the benefits of $12P. I suppose it would be an interesting exercise though, you'd need to figure out which TBI ECU is closest to an 808 and compare specs

[UCMatt]

Joining D9 and D10 enables the 'Peak and Hold' function of the driver for lower impedance TBI injectors.

[knuts2au]

Pulled mine to bits for a quick look, D15 and D16 are joined together on the PCB and go to a single FET, D3 is the earth for the injectors only (other side of the FET). D10 goes to earth on the PCB. Won't be much trouble to upgrade the FET to a bigger (higher current) one, and put a wire link for the return on D3.(so we don't cook the PCB track) all the parts have DELCO numbers on them which doesn't help much.
PeterN

[briney]

Joining D9 and D10 enables the 'Peak and Hold' function of the driver for lower impedance TBI injectors.

so just to be clear, i jumper d9 to d10 and then it'll happily run 2 2 ohm injectors ? or do i also need a higher capacity driver ? any software changes ?

[VK_3800]

Yes that's the theory, which seems to be supported by the documentation. I believe you should disconnect any existing earth on D10 and only jumper it to D9.

As far as the software goes well that depends on the rest of your setup. The biggest problem is that if say you wanted to run two TBI injectors on a V8, generally if your injectors are big enough to supply adequate fuel at full noise then they're too big to have enough control at idle and low throttle. The TBI ECMs have two injector drivers and the software alternates the injectors rather than firing both at once to get around this, but the 808 only has one driver. It does seem to work OK with the single injector TBI setup on the four cylinder cars.