Injector firing sequence?

[Gavin]

Can anyone tell me if the SETA injectors fire in batched or sequential configuration?
I think I remember reading that cylinders 1,2,3 & 4,5,6 fire separately in a batched configuration but I'm dot positive.

[jlevie]

The injectors are grouped in two banks of three. So each injector firing pulse will open three injectors. The engine does not do per cylinder sequential injection, like later BMW's.

[Gavin]

Am I correct then in my recollection that the injectors for cylinders (1,2,3) fire as a batch, and (4,5,6) are grouped as a second batch?

Also, are our injectors grounded and receive power to trigger, or do they receive constant power and a switched ground signal to trigger?

[nando]

Motronic 1.3 cars are semi sequential - meaning they are timed to the combustion cycle of the engine, but only in a batch of two. that is what the impulse sensor on the #1 plug wire is for.

they do recieve constant power and are fired by grounding them.

also, the batches are 1,3,5 and 2,4,6

[Gavin]

Thanks for the info.

I’m still working on my ITB setup, and while I wait for my ‘i’ head to be shipped to me, seized at customs, returned to sender, and resent to me, I thought I might bastardize a 12 injector set up just using a series of relays to trigger my GSXR1000 injectors in tandem with the factory set. Why? You might ask…. Just for fun really. I have a fuel piggyback installed to dial back the overabundance of fuel this would create (over and above the small amount of extra fuel I’ll need to run the ITB’s).

[nando]

I don't think that's a good idea - with high-z injectors, you will end up with really small idle PW's and possibly trouble getting the thing to idle at all.

[Gavin]

I suppose you’re right, I shouldn’t bother if I’m just going to half ass it.
Ultimately what I would like to do is run the stock injectors within the limited low RPM vacuum gradient I’ll be left with (once the ITB’s are on), & have the up stream 6 injectors take over most (but not all) of the fueling at higher RPM based on TPS. A TPS/MAP dual metering setup seems like a good idea to me. Now if only the computer I’ll need to do this wasn’t so expensive/complicated.