i have read here on the site that only one resistor is needed no matter what ecu you are using that the extra two resistors are for removal of the hac so if i run with the hac sensor then i only need to use the 2.4k resistor in the afm clip
vpc 1 vs three resistor question
- Thread starter koreyd
- Start date
I was also wondering the same thing. There is such limited resources when it comes to the VPC it almost sucks to have one :evil2:. I found this which is for the 86-88 installation, but is it necessary to disable the HAC system. It appears to me that the VPC may become messed up (or the ECU gets different inputs or outputs) when the HAC system begins to work. So, is that why we have the constant resistance between the HAC and E2 and VC terminals? If true, it is the only reasonable explanation I can come up with. I don't know if Supracentral has anything to do with the website i found but it is oldschool.supracentral.com, so who knows.
I'm actually at this point in my VPC install too. I'm not sure as to what i need to do in terms of the resistors. Can anyone clarify what the HAC is? And maybe explain what the resistors are supposed to do?If it makes any difference I'm running it with an SAFC?
The ECU needs to know the mass air flow into the engine. Our AFM detects volumetric air flow and need a correction to convert to mass airflow. The temp sensor is used as the primary correction since hotter air is predictably less dense. However, altitude also affects air density and the HAC is used to correct for that.
Since the VPC discards the AFM for a speed-density setup, it doesn't need the HAC. In fact, the HAC correction is going to make things worse so HKS disables the HAC to make the ECU think it is at a constant altitude.
One 89+ ECUs the HAC is embedded in the ECU, so this is no longer possible. I have no idea what HKS did to overcome that.
Since the VPC discards the AFM for a speed-density setup, it doesn't need the HAC. In fact, the HAC correction is going to make things worse so HKS disables the HAC to make the ECU think it is at a constant altitude.
One 89+ ECUs the HAC is embedded in the ECU, so this is no longer possible. I have no idea what HKS did to overcome that.
That does not make sense. The HAC signals are not available to the outside world on the 89+ ECUs. It is all contained on the PCB board inside the ECU.
3p141592654;1523325 said:
Thanks for the info, it makes a lot more sense now. Does anyone have any info they can share about the wiring it up with an safc?is there anything important to note?