DIY - Fitting an Apexi SAFC II to your gen1/2 Coupe

How to fit an Apexi SAFC II to your Coupe, including a very useful ECU pinout guide.

Many thanks to Marko

This mod can be discussed in the DIY section of the forum

Before we get started, you're going to need tools, time and patients. Tools needed are a sharp knife, cable cutters (or scissors), electrical tape and some crimps (or pliers). Time, say 2 hours to be safe, patients, well, that's up to you.

Ok first things first, locating the ECU! The ECU is on the driver's side under the dash board, it's easier to access if you remove the lower half of the dash from under the steering wheel, which is secured by 4 bolts if I remember correctly. Once this is gone, get yourself upside-down and look to the side for a great big black plug with a big mass of wires going into it, that's your ECU. Before unplugging it, make sure the battery is disconnected! Then unclip it by pulling the little metal shiny clip away from it and pulling the plug down over, it sort of folds out, give it a good pull, it's a tight little bugger! Once its out, untangle it from the other bundles of wiring and get as much slack as you can to make it easier to work on. Unscrew the plug cover and slide it off. Remove the tape to reveal the wires. This is when you need to start cutting wires!

Here's where the wires need to go, so familiarize yourself with where each pin is on the plug, the bigger wires at the bottom of the plug are where pins 1 and 28 are, whilst pins 27 and 55 are nearer the wires end.

S-AFC II Wire ECU Wire
Description Colour Pin No.
Power Wire (on/start) Red 24
Engine RPM Signal Green 43
Throttle Position Sensor Grey 19
Ground (closest to ECU) Brown 3
Ground (furthest from ECU) Black 3
MAP sensor IN White 16
MAP sensor OUT Yellow 16
Other Useful Pin numbers
Knock Sensor Pin 8
CMP Sensor Pin 42
O2 Sensor Pin 17
Intake Air Temp Pin 20
Battery Voltage Pin 52
Vehicle Speed sensor Pin 12
Engine Coolant Temp Pin 15
Memory power Pin 32

I listed the 'other useful pin numbers' just in case.

Firstly, start with the wires your actually going to cut rather than 'splice'. These are the MAP sensor connections, and it is only the one wire that needs cut, this is pin 16. Cut it about 2 inches away from the plug and join the apexi's white wire to the end of wire NOT going to the plug, join the yellow wire to the end going INTO the ECU plug. Their, wasn't that easy… oh, you HAVE DISCONNECTED THE BATTERY RIGHT? If not you might want to pack up now and go buy a new ECU! Anyhow, hopefully you did, and things are looking good.

Next are the ground wires, which again are on one wire of the ECU. Pin3. You're not going to cut this one, just splice into it twice to join the two earths. By splice I mean remove the insulation in two areas, and wrap the apexi's wires round the exposed wire. The brown wire wants to be joined nearest the ECU and the black slightly further away. Next is the TPS, again, splicing this into the wire which is pin 19. Next the engine RPM, splice this to pin 43 and finally the power, I used pin 24 for this, again spliced.

You should have just done this…

A few tips, I used the blue wire of the Apexi to monitor the O2 sensor voltage, this can tell you if the car is running lean or rich but ISNT RECOMMENDED! I've read reports of the Apexi screwing with the signal from the o2 sensor and messing with the ECU, although mine has been fine. If you want to do this splice into pin 17 and join the blue wire to it.

Another useful thing to do whilst you're down here would be to put a switch in the memory power cable, which is pin 32, this could then be located somewhere like under your stereo and allow you to reset the ECU when you like without having to disconnect the battery.

Next is to locate the Apexi. This is totally up to you, but I went for under my radio, I simply fed the wires thru to where I wanted it and mounted the Apexi accordingly. A little drilling is required here for the cable.

Ok now you're ready to plug the ECU back in, rebuild the dash, reconnect your battery and switch your ignition on but DON'T START THE ENGINE! The Apexi should power up fine at this point. If it doesn't, SWITCH OFF AND CHECK EVERYTHING! Once you're happy it is working, follow the instructions in the guide you got with it and get it set up. When ready, start the car up and you should be able to monitor most aspects of the engine thru it. Please note that the car should run as normal, if it doesn't, switch off and check everything again!

Finally, go to a rolling road, and get that new little toy set up and enjoy your new power/toy!

Hope this was helpful!

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