Piggyback Heaven : How To Install a Lexus SC300 AFC NEO

Piggyback Heaven : How To Install a Lexus SC300 AFC NEO


The Lexus SC300 is the USDM counterpart to the Toyota Soarer, a terrific luxury sports coupe found in Japan. The Soarer in the JDM ( Japanese Domestic Market ) is equipped with a factory 5 speed (R154 Transmission) and the 1JZGTE a 2.5 liter version of the venerable 2JZGTE.


And the 2.5 liter version of the legendary 2JZ is nothing to sneeze at either, capable of cranking out over 500 wheel horsepower on stock internals. Sharing many of the overengineering traits that make it’s big cousin such a popular and stout engine, the 1JZ can be found at a considerably cheaper rate for engine swappers.


In an unsurprising outcome however, the USDM version of the Soarer was equipped with a less potent engine the 2JZGE. Many turbo kits exist for this engine as it’s also found in the Non Turbo MKIV 1994-1998 Toyota Supra.

The 2JZGE turbo kits are a very popular NA-T modification
The 2JZGE turbo kits are a very popular NA-T modification

A popular fuel management option for those wanting to bolt on turbocharger power to their non-turbo 2JZ is the Apexi Super AFC NEO. At a low cost, you get rpm and throttle specific fuel tables that can be separated into a low throttle and high throttle settings in a compact form factor.


With the ability to “trick” the airflow or manifold pressure to the ECU, the AFC NEO allows you to adjust the fuel trims of your stock 2JZGE ECU in order to boost safely. You can take this a step further if you are able to locate a HKS VPC and convert your 2JZGE from a Mass Air Flow ( MAF ) operation to a Manifold Absolute Pressure. Today we’ll be installing a AFC NEO into a 1992 Lexus SC300 running a 2JZGE-T turbo kit.

Learn how to Install a SC300 AFC NEO

This kind of setup can net you around the same numbers as a 1JZ provided you make the necessary fuel upgrades.


Since this 1992 is a OBDI vehicle, we’ll also be showing you the OBDII procedure should you own a 1996-1998 Lexus SC300. Your ECU is located under the floor panel of your passenger side floorboard, the same as a MKIV Toyota Supra.



Pull up gently on your passenger side side panel to undo the kick panel that rests against the passenger side of the vehicle. Push in the two plastic tabs up at the top near the bottom of your dash, and slide the protective cover back so that your ECU and brackets are exposed.



Remove the nuts that secure the ECU down in it’s place after removing the ECU shield and foot brace. Your ECU should now be out and you should be ready to wire your Super AFC NEO into your SC300.


Now remove the ECU and flip the engine harness so that the back of the wires are facing towards you, reference this page for the SC300 pinouts, or simply follow this chart.


Now take your Apexi Super AFC NEO instructions and review the different types of wiring that you will need to finish your installation.


Since this vehicle is an OBDI 2JZGE, the Mass Air Flow Sensor that comes equipped with this year SC300 is a Karmen style Mass Air Flow Sensor. Similar to the DSM or Mitsubishi Karmen MAF, you will need to follow the wiring above to complete this install.


First we will begin with the RPM wire, which will be sending the tach signal to the AFC / ECU in order for the NEO to determine what RPM your engine is. This wire is the Green wire, and must be teed or spliced into pin 58 on the 2JZGE ECU.



Remember you should be looking at the front of the ECU when locating your wiring, or the back of your engine wiring harness for your 2JZGE. 

Next we will tee the throttle position sensor ( TPS ) wire into the ECU wire 43, which will enable the NEO to know what throttle position your vehicle is at.


Now you will be moving onto the Mass Air Flow Sensor ( MAF ) for your SC300, keep in mind that the OBDI 2JZ and the OBDII 2JZ use different types of Mass Air Flow. Locate your MAF wire on your ECU, which should be wire 66 and cut this wire in half leaving plenty of length on the harness side.

Splice the PINK wire into wire 66 leading INTO the ECU side of the harness, and then connect the orange wire to the harness side.


Next we will be wiring the power and ground to your AFC NEO, by tapping into the ECU power and ground wires. Depending on what generation AFC you own, you may or may not have 2 grounds or 2 power wires.

If you have the version of the AFC NEO that’s the latest generation, you will have two power wires one solid red and one red with a white stripe. It’s important that you wire these power and ground wires into the ECU harness correctly, and according to the Apexi instructions.

Connecting the Ground and Power Wire.


Take the BROWN wire from the AFC harness, and splice it into the ECU pin 69 close to the ECU harness plug. Now about an inch downstream of the engine harness, splice the black wire into pin 69.

If you have two power wires you will need to connect the red wire with white stripe first to ECU wire 31, and then connect the solid red wire in a similar fashion to how you wired the ground wires.

How to Setup the Apexi Super AFC in a SC300 NA-T

You should now be done with the wiring section of this install, plug your AFC NEO into the flying loom and then turn the key to the “ON” position to see if your AFC powers up.

Step 1 : Setting throttle position

Go to [main]~> [ setting] ~> [3. TH-Point] ~> [Lo-85, Hi-86]

Step 2 : Setting MAF type

Go to [main]~> [ect.] ~>[1. Sensor Type] ~> [KARMEN] ~>[in-12, out-12]~> [in-1, out-1]* (SELECT HOT-WIRE IF YOU ARE OBDII)

Step 3 : Setting the Engine Type

Go to [main] ~> [ect.] ~>[2. Car Select] ~> [Cyl:6, Throttle position:UP]

Step 4 : Setting Adjustment points

Go to [main] ~> [ect.] ~> [3. Graph scale] ~> [Ne=7000RPM]

Here is where you can determine which RPM points you want your NEO to adjust the fuel trims, based on load and throttle position. If you are unsure of what values to put here, speak to your tuner for more details.

Step 5 : Correcting Atmospheric BOV

The Dec. -Air values are used to compensate for air that you have released to the atmosphere, if you have your BOV venting to atmosphere. This step is not legal for most public roads, and if you are not sure on how to use this feature, disable it.

You have now completed the install of your Super AFC NEO into your SC300! Congratulations!

Happy Boosting!