Petrified.Rabbit wrote:i just looked around too, most suggest you have to share or double (some) sensors so the megasquirt gets all of its readings, and basically unplug the fueling harness from the ecu. but be careful with this as if the fueling the computer wants to send out doesnt match the o2 reading you will get a code, and i believe the etech retards timing as well correct?
never used megasquirt as piggyback, nor do i know the etech inside and out..
If hes using the 2.0L its the DTEC
![Razz :P](./images/smilies/icon_razz.gif)
Anyways it has to do with the management more than the motor itself.
If you are going to totally cut off the injectors from the stock ECU, I would expect some issues. This being an OBD2 ULEV vehicle, the ECU is anal about fueling and emissions. During idle, cruising and part throttle conditions the ECU will be trying to run the fueling in closed loop mode with the O2 sensor. If you have your wideband hooked up you will see the AFR's oscillate constantly between low 14's to low 15's during those conditions. It does this to get the best tailpipe emissions while also prolonging the life of the catalytic converter. What I'm trying to say is that the ECU watches the O2 readings in correlation with fuel being added very closely. If you take away its ability to adjust fuel, you will likely get some sort of DTC with a CEL (maybe not right away tho). Once a fuel/O2 related DTC is activated, the ECU will be in a sort of limp mode with slightly less timing and worse throttle response. This is one of the reasons I am planning for standalone on my car this summer.... I am sick of having to clear DTC codes for stupid O2 and emissions related stuff.
Overall with that method, I believe the car will still run ok, just that it won't be optimal. If you could take control of both FUEL and TIMING, then you're really in an ideal situation. Another option is to get an O2 simulator for the primary O2 sensor that would splice into the signal line and continually feed a fake oscillating O2 signal to the ECU, so that you could do whatever you want with the fuel and the ECU will be happy. Let us know how it goes it any case.