Can I leave my stock ECU in place to control non-EMS related gadgetry, while letting the MegaSquirt control the engine?
Yes you can– This is what is known as a ‘Parallel Install’ and on some newer cars where the OEM is putting more and more responsibility on the ECU (more than just an Engine Management role) you may need to go this route. Some of the other responsibilities that OEM’s are putting on the stock ECU are gauge control, cruise control, auto tranny lockup, etc. Youd basically leave the stock ECU in place, and leave the stock sensor inputs connected to it. Then youd 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. Youll 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. T
Yes you can– This is what is known as a ‘Parallel Install’ and on some newer cars where the OEM is putting more and more responsibility on the ECU (more than just an Engine Management role) you may need to go this route. Some of the other responsibilities that OEM’s are putting on the stock ECU are gauge control, cruise control, auto tranny lockup, etc. 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 (you can share these but it can be troublesome, read up on it if you want to share IAT/CLT with the stock EMS), 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 the E
