I was able to pick up a cross fire system complete and was wondering if I could use bigger throttle bodies (two barrels)with that computer? I thought this would be a good way to use two throttle bodies but will the computer be able to run the two bigger throttle bodies? what was that you mentioned about two Q-jets? Where they computer controlled and what intake did you use?

 

Just an observation but do you want to run 2 2 barrel TB units? If that's the case then you might be in the same boat as me. The problem I'm having is running 4 injectors off of 2 drivers. The ecm was designed to run only 2 injectors just like in crossfire, I just wish there was an easy adaptor or some plans to do it.

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, Jon (350 TBI!)
91 Red My website

 

What I did was had the TBs machined out for 2" butterflies. The cross fire runs two single barrel Throttle Bodies.

While not a perfect answer, there is the option of just running some Power MOSFETs and forget the peak+hold strategy. There has been comment some time ago that that would work. Just be sure to have a ton of heat sinking for them. I'm not saying this is a definete answer, but might be worth investigating. Also, a good excuse for putting together an ecm bench.

 

The answer is pretty reasonable, if you are proficient at soldering. The parts you need would be peak and hold drivers, made by National Semiconductor, I beleive the part number is something like LM1949 or something like that(it is on the efi332 website, or GMECM website). The driver circuit would be as shown in the datasheets, and they give examples for low imdepance injectors. The things you need are power transistors(make sure you heat sink them) and power resistors(part of the current sensing ckt). YOu will have to terminate the existing injector driver/add a resistive divider, and add an inverter(HC04 chip) to make sure the injector drive signal is the right polarity. I'm still looking into this circuit, if I get something drawn up, I can post it. Alternately, ONSEMI makes a driver that is completely self contained, no external transistor, but the right logic interface is still necessary. Once that is done, chip tuning will be necessary for things like AFR, and idle(oh, the IAC's would be connected in parallel). All this of course depends on how well you are capable of building circuit boards, but it is well within the realm of the do-it-yourselfer, using prototyping materials available from Radio Shack, etc.