MPM

I've got an 88 GTU with a ported N/A engine. I'm in the process of installing a fuel only computer(SDS EM-2) and was wondering what the those of you with a similiar setup did to keep the factory ignition functional? I seem to remember a few Megasquirt installs where the factory ignition was utilized.



If it matters I'll be using the factory intake and stock injectors with all the emissions related items removed.



Any help is greatly appreciated.

j9fd3s

if you keep the stock ecu hooked up it will run it, just use the sds for the injectors

jwx

what you could do is switch to the earlier(I think it was the 84-85 GXL_SE) 13B ingition.

MPM

Thanks. I was hoping it was something as simple as not touching it.

j9fd3s

factory ignition works like this:



cas-->ecu-->coils



if you take the ecu out theres nothing to fire the coils, you can however just have the fuel only ecu run the injectors and leave the stock ecu hooked up to run everything else

dcrasta

Anyone here doing that with a megasquirt. I have a 88 TII that I want to add a megasquirt system to. I was hoping to use the fuel computer to compensate for boost mods and maybe with my hybrid 90 turbo/manifold be able to go 15-20 psi and still preserve good a/f ratio. I just need information how they work together. ANyone good websites or links?



Thanks

(new to turbo rotaries)

mazdaspeed7

I guess this is as good of a place as any. As some of you may or may not be aware, Im running a Megasquirt controlling fuel, and the stock ecu controlling ignition on my 90 GTU.



The following info is S5 specific, but the S4 is easier.



The factory sensors necessary for proper timing control the CAS, TPS(narrow range), and the coolant and air temp sensors. The afm, full range tps*, BAC, AWS solenoid are not necessary, but you may want to keep at least the BAC if you have a/c and/or p/s. I havent tried unplugging the pressure sensor, but I dont see why it wouldnt work. Between that and the tps, you may not have functional vacuum advance on the timing, though. Ill try that this week and post the results. The BACt takes care of the idle compensations. I used the stock full range tps for the MS, BUT that would be a problem for those with functional OMP's. Roger Enns modified the code to allow for no TPS, which would work great in this situation. It uses only the MAP for load sensing. Colin should have this S record, I dont right now.



The only problem I have is the check engine light is constantly on. Ive been meaning to cut the wire from the ecu to the light so it will go out, or maybe put a switch on it so i can still use it for checking codes if need be.





If you have any other questions, ask away.

j9fd3s

another idea would be to use the megasquirt on the secondary injectors and leave everything else as is, this way the car will start and run the same and you just tune the power

mazdaspeed7

But then you have to keep the AFM.



FYI, I did just that though. I tuned the secondary map, and then went back and tuned the primaries afterwards.

dcrasta

Sounds great. Did you wire this into your car's harness and then disconnect secondary injectors into the megasquirt. Did you wire it all up? Im a little intimitated by the whole thing dont want to destory anything hahaha.