A wise contributor on this forum wrote this.
"The High Altitude Compensator is a barometric pressure sensor. It is used in the calculation of mass air flow along with Karmann Vortex frequency and Intake Air Temperature inputs. Without a functional HAC, the car will run differently according to barometric pressure. It will run richer in low pressure conditions and leaner in high pressure conditions. The closed loop operation will compensate fuel trim to some extent. Spark advance is also pressure corrected but there is no "fallback" sensor to make up for the lack of correction without the HAC. Spark timing is advanced inversely to barometric pressure.
The corrections made on account of the HAC sensor are small under normal conditions. In extreme conditions, such as a hurricane or driving through a large mountian range, the corrections can be significant."
This sounds like a prime candidate way of "tuning"
We can trick the ECU into thinking the barametric pressue is changing to change timing advance.
Anybody have any bright ideas?
"The High Altitude Compensator is a barometric pressure sensor. It is used in the calculation of mass air flow along with Karmann Vortex frequency and Intake Air Temperature inputs. Without a functional HAC, the car will run differently according to barometric pressure. It will run richer in low pressure conditions and leaner in high pressure conditions. The closed loop operation will compensate fuel trim to some extent. Spark advance is also pressure corrected but there is no "fallback" sensor to make up for the lack of correction without the HAC. Spark timing is advanced inversely to barometric pressure.
The corrections made on account of the HAC sensor are small under normal conditions. In extreme conditions, such as a hurricane or driving through a large mountian range, the corrections can be significant."
This sounds like a prime candidate way of "tuning"
We can trick the ECU into thinking the barametric pressue is changing to change timing advance.
Anybody have any bright ideas?