'7749 Low-Z injector driver modification v.USDMECM

Ecu Hardware Modifications
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Six_Shooter
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'7749 Low-Z injector driver modification v.USDMECM

Post by Six_Shooter »

This is for the 1227749 USDM ECM. I know most people around here are running Australian ECMs, but there are a few of us North Americans here. ;)

Anyway, this is some information that I thought would go well with the scope of this forum, and very well might apply to more than just the '7749, at least in pricipal and values.

This is for running 8 low-Z injectors.

http://home.comcast.net/~p-928/749mods.html
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Re: '7749 Low-Z injector driver modification v.USDMECM

Post by antus »

Thats a nice mod, I never thought of replacing the drivers to run low-impedance injectors. Its probably a better way to do it than external low impedance driver box. It probably wouldnt be to hard to base other delco ecu mods around that one.
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Re: '7749 Low-Z injector driver modification v.USDMECM

Post by briney »

digging up an old thread. if i wanted to run a falcon tbi setup, one of these looks like it'll work.

http://www.jaycar.com.au/productView.as ... rm=KEYWORD

any suggestions ?
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Re: '7749 Low-Z injector driver modification v.USDMECM

Post by briney »

also, i'm looking at my computer which only has 1 driver. all the resistors i look at are surface mounted. would changing the driver only be ok ? or would that mean it wouldn't work ?
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Re: '7749 Low-Z injector driver modification v.USDMECM

Post by antus »

I think VL400 has looked in to what would be involved.

This is not an answer, just some info.. .what i know of low impedance aka peak and hold, the ecu needs to supply high current for a short moment (something like 8 amps per injector I think) to get the injector open, then its up to the ecu to then limit the current to about 2 amps to hold it open. Thus I think the fuel controller needs to be set up for it. Im not sure what happens if it just holds the inejctor at 8 amps for duation of the injection, but I would want to know before I tried it.
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Re: '7749 Low-Z injector driver modification v.USDMECM

Post by briney »

thanks antus. i've just been looking at how the falcon stuff works and they are peak and hold. in all honesty i'm probably better off not being a poof and just making the mpi manifold straight away. then using high impedance injectors.
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Re: '7749 Low-Z injector driver modification v.USDMECM

Post by VL400 »

Yeah I couldnt get the '808 to do peak and hold - was drawing near 8 amps on the injector from memory, but never went to a lower current hold condition. Will try again sometime with a car battery, my bench supply is only 10A so was starting to run out of puff.

There was some recent discussion here .. https://pcmhacking.net/forums/viewtopic.php?f=7&t=2245
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