By Mark Higgins (aka DirtyLude)
Last Updated

• Introduction
• Get at the ECU
• This is Where the Wires Go
• Testing
• Mounting the Unit
• Test Drive
• Items You Have Left Over
• Where I Got It From

Introduction -

The J&S ignition retard unit listens to a sensor placed on the engine for an audible knocking noise from the engine. This knocking noise alerts the unit to pre-ignition, detonation or 'pinging'. The unit can be set to retard ignition on only the cylinder which is knocking.

This modification prevents damage to your engine due to other modifications you may make. Advancing timing, forced induction, high compression, radical cam timing can all cause your engine to ping.

I didn't install this unit the way the instructions say. I tapped into all the sensors and spliced the ignition control wire right at the ecu. Also, instead of using the knock sensor that J&S supplied, I used the stock knock sensor. This way I didn't have to go through the firewall at all, which is a pain on the 5th gen. If you want to do it the way the instructions say, then they are pretty straight forward. If you want to do it my way then follow along.

Get at the ECU -

You need to take out the passenger side mat and pop out the plastic kick panel that's between the door and the back of the passenger side foot area. This allows you to pull the rug up exposing the cover for the ECU. You'll need a 10mm ratchet with an extension to get the 4 nuts off that hold the ECU plate down. Once you have the nuts off you can pull the bottom of the plate out and up, exposing the wires and ECU wire harnessess. You'll need to cut off some of the tape that hold the wires together so that you can isolate the specific wires and tap into them.

If you want to do a test harness you can just strip a bit of each of the J&S wires and slip them into the wire harness in the appropriate spot. Unfortunately you can't do that with the ignition control wire which must be cut.

This is Where the Wires Go -

1.1 ECM connector A / wire 20 / YEL/GRN - Ignition Trigger Wire

- This wire is going to have to be cut. The J&S GREEN wire is attached to the wire going towards the ECM. The J&S WHITE wire is connected to the wire going out of the firewall.

1.2 ECM connector A / wire 11 / YEL/BLK - Key On Power wire

-The J&S RED wire must be spliced into this wire.

1.3 ECM connector D / wire 6 / RED/BLU - Knock Sensor

-The J&S BLUE wire must be spliced into this wire.

1.4 ECM connector D / wire 1 / RED/BLK - Throttle Position Sensor

1.5 Ground

- Under the plastic kick panel that you removed to get at the ECU there's a grounding bolt with a few other black wires going to it. Ground your J&S BLACK wire here.

Dual Monitor only

2.1 ECM connector D / wire 7 / WHT - Oxygen Sensor

- The J&S Monitor GREEN wire must be spliced into this wire.

2.2 Ground

- Ground the J&S Monitor BLACK wire same as the black wire above.

Testing -

Plug the monitor cable into the unit. Once all the wires except the throttle position sensor wire are connected make sure the sensitivity dial is somewhere around minimum and try starting the car. Turn the sensitivity dial towards max until some knocking is detected by the unit when you press the gas. If the car doesn't start or the unit never registers any knock at max sensitivity, check your wiring again. Somethings wrong. If it doesn't start, there's four wires which could be your problem; the two that go to the ignition control wire, the power wire, or the ground wire.

Once it's running, if you haven't already, cut the wires to the proper length to reach it's mounting location. To permenently connect these wires either use the blue connectors to tap into the sensor wires or strip and solder the J&S wires onto the sensor wires.

Mounting the Unit -

Mount it anywhere inside the passenger compartment. The glove compartment is a good choice or mounted on the passenger side of the centre shifter console. You'll need to route the wires to the ECU under the passenger side foot rest. You'll need some large loom to cover the wires from the unit all the way back to the ECU. For those of you with the dual sensor use some small loom to cover the Oxygen sensor and Ground wire back to the ECU.

Test Drive -

Take it for a drive and set the sensitivity so that it's just below where the regular engine noise is fooling it into retarding cylinders.

Items You Have Left Over -

• 1 Knock Sensor
• A whole lot of wire
• A whole lot of wire loom
• A silly purple velvet bag

Where I Got It From -

I bought this unit during a group buy from the Endyn boys (www.theoldone.com). Larry was extremely helpful and seems like a down to earth nice guy. This is not a cheap mod. I got the unit for $400 USD and the dual monitor for $112 USD.