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Did some diagnosis on the 99 with EMU this weekend....confirmed that rear o2 is putting out a signal. When the car warms up, and goes into closed mode at idle [I think], the idle becomes terrible. I end up throwing misfire codes, like P0302.

Clear the code, cool the car off - idles beautifully.

This car has 440 injectors and a MAP to run the EMU. I have also relocated the IAT to the exit of the intercooler. The ECU still uses the MAF for its functions.


I am not versed enough in EMU to understand where to move next...

The goal will be to get through the O2 sensor check and finally get emissions tested, but I cannot do that if I am continuously throw P03xx codes due to what I guess is an over-rich idle condition after closed mode starts.

How do I get the EMU to take over the function in this case? Or how do I get the ECU to recognize the larger injectors. How do I get the ECU and EMU to handoff to each other correctly?

PS - EGR tube not available, bu GA allows 2 unfilled readiness checks, so I think I can live with that, as I think EGR is the last test in the readiness cycle.

Thanks in advance for any advice.

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Quick update - earlier, I got a hint from sturovo to check if the O2 was shunted to the EMU. Just one is - signal from the front O2. This is being run into the analog voltage input and back out of the analog voltage output. Also - the sensor ground send to / from the EMU, but that is needed for the injectors.

For my next move, I will look into the menus of EMU, and likely break and short the connection back to the ECU.