ST165 VPC Installation

Here is a few notes about ST165 VPC installation. There is no harness for the ST165 so it MUST be hardwired. There are a few extra notes here that are not covered on ST185 installation. Note that a Supra 87-88 VPC harness can be converted to work for the ST165, so that you don't have to splice into your wiring. Please see me for more explanation.



MR2 Stock Injector chip for VPC

HKS VPC Air temperature sensor

HKS VPC 3 Bar Map Sensor

Resistor for Air Temp Mod

Wire Taps or ability to solder to existing wires

Some way to turn on fuel pump





Just tap the wires! You won't cut the AFM (VS) signal since when you remove the AFM there will be nothing going to that signal wire. The VPC yellow wire will then send the signal to the VS wire.

A resistor must be installed between the THA (air temp sensor) and E2 (sensor ground). See this page for more details on that mod. CLICK HERE

The air temperature sensor must be installed after the IC. The throttle body is the ideal location. This will require drilling and tapping of the throttle body. You can also use the intake manifold if desired. This is where the supra TT guys put their air temp sensor and we can see it works out great for them.

The map sensor for the VPC must have a source directly from the manifold. You can tap into any line coming directly from the manifold. Be sure to use the filters included with the kit, so that dirt does not find it's way into your expensive sensor.

Note: The AFM on the ST165 also turns on the fuel pump. You need some way to turn on the fuel pump once the AFM is removed. For testing, you can turn on the fuel pump manual by bridging the +B and FP ports of the diagnostic box. But you need some way for the fuel pump to be turned on when your car is started. You can wire the fuel pump to be on with IGN on, but remember that this will make the fuel pump always on when you are driving. This is great, but if you crash, the fuel pump will still be on and can possibly be dangerous. Seek help if you would like to make a proper fuel pump switch that will be safe. If you do turn it on this way, at the very least make some sort of fuel cut off switch accessible by the driver in the event of an accident.


Tuning should be performed by a person familiar with VPC, hopefully a professional. You can ruin your engine by "playing" with the knobs. Set all to zero and start the car without the AFM. It will take a little while, but it will settle down smooth idle. If the idle is rough you can use the idle adjustment knob. You might find that the idle must be adjusted at times depending on ambient conditions.

Click here to view the actual HKS VPC documentation and notes

An MR2 owner noted on his relatively stock car that these settings started him out best:

Response -2

Gain -1

Idle +3


Many have asked about the gains associated with removing the AFM. There is no correct answer. It depends on your car. If you have a turbo upgrade, or are running a lot of boost, the gains will be higher. For example, if you put a VPC on a stock car, the gains would be very little. Just know that it's always GOOD to remove the afm. Some have reported gains around 20 hp, depending on their mod level.

More questions? Email us