Issues with piggy back Air fuel 'interceptor'. Dam car's ecu safe mode kickin in.

[bajachris88]

Hi. I have just assembled a jaycar Digital Air fuel controller to intercept my 0 to 5 volt output on my MAP sensor on my 1990 5sge celica (5sfe ecu).

The input and output voltages are all great, no worries, as the signal has to go through the circuit when its turned off, but it just bipasses alot of the chips/processors. But! the ecu kicks into safe mode as soon as the controller is turned on and the signal gets processed, despite having a right voltage output and set to an 'unmodified' signal.

It triggers the 5sfe ecu to give me an engine warning light in regards to the MAP sensor and goes either into this gay gutless safe mode or stalls.

How can i get around this? Is there a way i can get the ecu to just relax and chill and take the signal?

Regards,
Chris.

[amichie]

Does the Jaycar gadget and the ECU have the same ground reference?

[bajachris88]

No.
Would that affect it? Cause it says the right output voltage with a multimeter (between it and ground), then as soon as i wiring up the output to the MAP it says 0 Volts (with the ground on the power supply)

Its just grounded on the chassis.

[The Last Streetfighter]

Yeah, I think you really need to pick up the same ground as the ECU is using.