The HKS Vein Pressure Converter is one of the most wildly successful piggyback computers of the mid 90s. This handy fuel management device powered countless turbocharged vehicles by eliminating the OEM air flow meter. Such vehicles as the 1994-1998 Toyota Supra, 1993-1995 Nissan 300ZX and 1993-1995 Mazda RX-7 are just some of the turbocharged applications that enjoyed the benefits of ditching the MAF.
However as cutting edge as many of these fuel computers can be, the VPC was one of those piggyback computers that unfairly received a negative stereotype. Users were installing their VPC and blowing up their motors, with many people being turned off before they could even learn what the VPC exactly did. The HKS VPC is no longer in existence, but for the lucky few that still have this unit, or maybe purchased a used one, we’ll be showing you how to install a HKS VPC today in a 1997 MKIV Toyota Supra.
To kick off our How To Install a HKS VPC Guide, let’s take some time to understand what the HKS VPC piggyback computer does. The Vein Pressure Converter can eliminate the ECU’s dependency on the OE air metering devices most commonly found in late model vehicles. Because of the inherent restrictions the mass air flow meter (MAF) represents, it’s easy to see how powerful a turbocharged application can be when using the VPC.
OEM air flow metering devices, such as Air Flow Meters and Air Mass Sensors (Hot wire / Karmen Vortex types) can restrict the amount of air being ingested as well as fail behind when the performance wick is turned up. Eliminate the bottleneck in your intake design and do away with MAF overrun with the installation of this HKS VPC unit. By installing the VPC you can physically eliminate the OEM air meter and convert your vehicle to a speed density system.
Powered by a 16-bit processor, the VPC reads it’s own intake air temperature sensor and absolute pressure transducer (B-MAP sensor) signals and then converts those signals to one that is recognizable by the factory ECU. Flashable EEPROM gives users further flexibility when it comes to programming the air compensation and fuel compensation tables to take advantage of larger turbos, bigger intake piping and larger injectors. This is about as close as you can get to a fully standalone system, without the huge price tag of the expensive ECU’s.
How to Install a HKS VPC
Before we get started on our How To, please make sure you understand what kind of project you are undertaking. If you purchased this HKS VPC used, make sure you know what ROM chip you own, and how it affects your vehicle and the conversion values. Just because this is technically a piggyback unit, does not mean your engine cannot be damaged from this install. Be aware of what you are doing and like all tuning computers, the HKS VPC is fully capable of turning your motor into a horsepower demon, or a broken lawn ornament.
To begin our How To Install a HKS VPC in our 1997 Anniversary Edition Toyota Supra TT, open the passenger side door and slide back the passenger seat as far back as it can go. Disconnect the negative terminal of your battery to ensure no damage occurs to your ECU or VPC.
Next pull up on the passenger side carpet to expose the ECU cover and the 10mm bolts you need to access to remove this kick panel.
Remove the kickpanel and take a look at the main 2JZGTE ECU, unbolt the main engine harness by undoing the bolt. This piece of the harness is called the E9 connector in your 2JZGTE, and it’s a one piece unit that connects two of the main blocks on your ECU. Most of the wires from the VPC will be tapped here, so unplug this bad boy and let’s get to work.
With your ECU unplugged, we’ll be wiring in the VPC and possibly a Apexi Super AFC or GCC depending on whatever piggyback you will be using to “fine-tune” the VPC signal. We’ll be including both sets of instructions on this article, and if you need a How To Install a Super AFC in a 2JZGTE Supra, click here.
There are several flying loom connectors on your VPC, we’ll be addressing the nine pin connector that should be wired inline of your 2jZGTE ECU. The nine pin harness is comprised of a few wires, which we will show you below.
The first wire in our How to Install a HKS VPC Guide, is PIN 58 found on the E9 plug of your 2JZGTE ECU. Pin 58 is the 2JZ tachometer signal, and this wire must be connected to the WHITE VPC wire on the nine wire harness. Pin 58 is normally yellow with a red stripe, and you must terminate the END of this wire to the white wire on the nine pin VPC harness. If you are installing a Apexi Super AFC NEO in conjunction with the HKS VPC, wire the AFC tachometer signal BETWEEN the white wire and the ECU.
Next we’ll be wiring in your low reference signal or chassis ground for your HKS VPC. Take the black wire from the nine pin harness and connect this wire to the 2JZ ECU ground, which is pin 69 labeled 1 in the diagram below. If you are wiring in a Apexi Super AFC, make sure the VPC ground is BEFORE the AFC ground wires.
The Mass air Flow signal wire is the next up on our guide, and we’ll be cutting this wire to wire it into your VPC. If you are using a AFC in conjunction, leave enough slack for you to solder the connections. You will be wiring in the MAF signal IN which is located on pin 66, labeled 2 in the diagram below to your AFC or piggyback computer.
Take the other half of PIN 66 and connect it to your piggyback in question, if you are wiring it into a Super AFC, connect the WHITE MAF OUT wire to the YELLOW wire on the nine pin VPC harness. Remember that you are wiring the MAF OUTPUT to the yellow wire, not the input.
The last wire we’ll be connecting is the red VPC power wire, and this one will be connected to your 2JZGTE E10 plug, or more specifically PIN 31 on the E10 plug.
This is labeled as the EFI Main Relay Switched Power in the diagram above, and will supply the VPC with direct power with the key set to the “ON” position.
Now with your VPC installed, you must mount and run the harnesses for the extra sensors required to operate the VPC. Now all that’s left is setting up and tuning your HKS VPC, which we covered in How to Tune your VPC article found here.
Have any questions on our How to Install a HKS VPC Guide? Leave them for us below!