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hi everyone,

I have a HKS VPC, I have wired it all up onto my car and checked all the signals with a multi-meter. At idle the VPC is sending about 1.3volts to the ECU and then the volts increase at rpm and throttle, hence the MAP sensor is working and the signal is being processed and sent the ECU. I understand that the AFM operates between 1 and 5 volts, so this should be fine.

However, the ECU is constantly in open loop (think I got it the right way around - closed loop is reading the O2 sensor and fluctuates) I know this from my AFR meter (jaycar), ie it is not fluctuating and just reads rich all the time, plus you can smell the fuel.

So, any thoughts on why the ECU is not happy. When I put it back to stock with the AFM, everything is okay again????

Maybe the VPC is trashed (it was second hand)

Thanks for any help!!
Si.

Is this on a 1.6? Are you aware that the AFM voltage falls as airflow increases?

Yes it is on a 1.6 - so the voltage is inverted. I think I remember somewhere that the 1.8s are the opposite way around. I guess that is the problem then.
Thanks.

put the stock meter on again and do some measurement. I think it's meant to be about 3.5 - 4.0 V at idle, falling to about 1.5V at redline WOT.