MSefi.com read only forum (Jan.15,2018)

Have a new project to work on: 1998 Blazer that I would like to install a V-8 using Megasquirt. My concerns are "What isn't going to work properly after the install?" From what I have been reading, the PCM has most controls built into it such as cruise control, transmission control, A/C, etc. Currently this truck has the 4.3L with 4 speed automatic, 4L60E, 4X4. My plan is to inject with TBI using HEI distributor.

I beleive that if I run the Megasquirt parallel to the factory computer, I should not have problems with the transmission or factory tach. The concern is how do I get an accurate RPM signal to the factory computer? Can I split the wires coming from my 8 pin HEI distributor to feed signals to both computers? The factory system uses a crank trigger that I believe just replaces the reluctor in the distributor sending the signal to the HEI module that is attached to the coil. I am pretty sure that only a coil wire runs to the distributor. Maybe just get a crank trigger for my older V8 to send the RPM to factory PCM and run distributor for the Megasquirt?

What about MegaShift? Is this available to work on this application?

Are there any other electronic problems that I may have? Would be nice to also have the factory fuel economy display to work, but I am sure that is asking alot.

This is a "budget" build(if there is such a thing!), so I do not want to buy a similar year Vortec V-8 and have the factory PCM reflashed. What fun would that be?

Getting a correct tach signal to the stock ECU is going to be tricky. Getting a signal to the dash tach isn't quite as hard but you may have to swap it out for a V8 tach.

The MegaShift is available, sort of. It's based off the GPIO board. Right now we have GPIO boards on their own, which you'd need to add a case and the through hole components to. We plan to have a kit ready in a week or so with the MegaShift components too. For more information on MegaShift, see this link:

http://www.msgpio.com/manuals/mshift/index.htm