megasquirt!---------- some questions

[02 Vortech]

im just finishing up my 60-1 rearmount turbo set-up on my blazer and im wanting to swap out the stock spider injection with a marine intake manifold that has MPFI- I need a system that can piggy back my ecu and allow me to run more than 14psi- stock 2bar map sensor is holding me back as well as stock 19lbs injectors.

i was wondering if i could run an MS2 piggy back my stock 4.3L computer to control the fuel/spark and boost maps, as well as bigger injectors- and let the stock computer run the the transmission functions

[FoundSoul]

You can-- You’d basically leave the stock ECU in place, and leave the stock sensor inputs connected to it. Then you’d run a new CLT and IAT sensor for the MegaSquirt, and then share the TPS and O2 signals between the stock ECU and the MegaSquirt. You’ll disconnect the spark output(s) from the stock computer and wire the spark input to the MegaSquirt (pin24). You should be able to share that signal in most cases. Next wire the MS spark output (pin36 usually, depends on model and mods)to the stock igniter or directly to the coil if modded for direct coil control. Then disconnect the fuel injectors from the stock ECU and wire them to the MegaSquirt. This will basically give your factory ECU control of everything but the engine, and give the MegaSquirt control of the engine.

Note that's just a quick rundown, and not necessarily in the order you might go about things, and I can't promise you I thought of every bump in your road. It might be best to start with fuel control, go ahead and do all of the above EXCEPT the spark output change (you do need the spark input shared with the MS at this point). This way you've got full fuel control, but the stock ECU is still controlling ignition. You can dial in your fuel map and get the car running good, and then move spark over as well with this transition being much smaller than taking it all on at once. Not to mention you'll know the MS ECU and the tuning software MUCH better.

[02 Vortech]

alright cool- thanks for the help man- i will be ordering the megasquirt sometime around x-mas- that really sounds simple enough- do you know where i can find a wiring diagram of my vehicle??

also does the MS batch fire or can it do sequential firing as well?

[Matt Cramer]

It runs in batch fire. Normally this is not much of an issue on most installations.