S13 Silvia Tuning

Installation is fairly straight forward, with only basic tools required. Electronics knowledge needed is minimal, just a decent soldering iron to ensure neat connections. When knowing exactly what needs to be done, the entire process could be completed in around half an hour. Thanks to DumHed from SilviaNSW for his great help and guidance.

Items required

The minimum items required are as follows:

Daughterboard	Just to make sure people are paying attention
Socket (supplied with board)	Remember this too!
Socket Set	Removal of ecu from car
Soldering Iron	Installation of socket, etc
Solder braid or a Solder sucker	Removal of factory solder
PCB cleaning spray	Removal of factory applied protective sealant
Phillips-head Screwdriver	Opening of ecu casing

Optional items are as follows:

Bubble wrap	Insulation and protection of board
PCB protective insulation spray	Resealing of soldering

The Process

	The factory ecu in the S13 Silvia is behind the passenger side front kick panel. This plastic cover is removed by two screws and a clip, with the first screw in the sill cover possibly needed removal to give a little bit of extra room. Once removed you should be greeted with a view like that shown in the picture to the left.
	Installation requires that the entire ecu be pulled from the car, and luckily this is simple too. Two silvia bolts above and below secure the casing to the chassis, remove these and unclip the plastic plug that holds the wiring loom to the mounting bracket. By now the casing should be unattached to the car except by the main connecting plug. Use a socket to unscrew the last remaining screw that holds the plug into the ecu. This is an excellent and reliable way of connecting to wiring loom to the ecu, it will never come undone unless it is unscrewed. Don't try to plug or unplug the loom, the screw is the only way to connect and disconnect it. There is no need to unclip the clear plastic cover. The ecu should now be completely seperate from the car and ready to proceed with daughterboard installation.
	Next remove the front and back covers from the ecu casing with a Phillips-head screwdriver, to expose the electronics. The front side is that which has all of the electrical components and the underside is obviously the other. At this stage you should be able to spot the location that the socket for the daughterboard will be soldered in. It is the 2 x 20 formation of solder dots just underneath the writing "JECS". First spray PCB cleaner to remove the protective coating from the solder dots, and clean up the area. Apply the soldering iron to these solder dots and then use either solder braid or a soldr sucker to remove the factory solder. This should leave just holes, ready for the socket to be soldered in.
	Note the orientation of the socket. It is placed on the upper side of the PCB, so that the exposed side makes a plug for the daughterboard to plug into. Solder the pins on the underside of the board making very sure that the soldering is neat and that no bridges are formed betewwen the pins. You wil notice that the socket has a cutout on one of its long flat sides. It makes no difference whether this is facing the "JECS" writing or the opposite direction. At this point you may wish to apply a spray on protective coating, but this is optional.
	The final alteration to the ecu PCB is to move a small resistor. On the underside of the board is a tiny rectangular resistor marked with zeros, placed in an area marked "CJ1". To make the ecu read from the daughterboard as opposed to its internal memory, this resistor needs to be moved to the join marked as "CJ2". Use PCB cleaner spray on the immediate area and then unsolder the resistor and solder it in in its new location. The picture to the left shows how the ecu will look when the modification is performed correctly. The area in question is located just to the right of the printed on graphic "M4". Note that a switch could be installed to alternate the circuit between CJ1 and CJ2, thus changing operation from internal memory to daughterboard reading. If the in the future you wish to remove the daughterboard completely, this resistor must be reverted back to original placement for the car to run properly.
	You may now plug in the daughterboard to see how it fits. The original casing will fit back over the daughterboard with no problems, but you may wish to protect the daughterboard and ecu hardware with some foam or bubble-wrap insulation. Just make sure whatever material you use it is not conductive, or there is a great chance of a short and permanent damage to the car. Here is a strip of bubble-wrap has been glued into a loop so that it will fit loosely over the daughterboard.
	The picture to the left shows the daughterboard in place with the protective cover. At this point all that needs to be done is to put everything back together. Obviously if you were planning to be fiddling soon after installation you would not put everything back together, to ensure easy access.

Potential Problems

It is very easy to plug the daughterboard into the socket so that the pins are not correctly lined up. When this happens two pins will not be connected either side and the others will be mis-matched. When you start the car, it is the equivilent of not having the daughterboard inserted at all. With the factory programming disabled from the resistor swap, you will immediately notice the effect. The car wil run and even drive, but it will cough and stutter terribly and almost stall every time you apply some throttle. Obvious signs are a lumpy idle, running rich to point that black smoke is visible even at idle.

The solution is to disconnect the battery for a short while, which will reset any fault errors in the ecu. During this time re-insert the daughterboard correctly with all pins inserted. When power is back and the car is started, it still may take a minute or two for the car to recover from its choked stage. A few presses of the throttle should should burn off excess cylinder carbon deposits. A short drive around the block should do the trick.

Because of this it is strongly recommended that the daughterboard only be inserted when full concentration is being used. Please note that the car will not mind the board being taken out while it is off, just as long as it is inserted correctly for start up.

Another thing that may upset the ecu is to switch between the daughterboards maps while the engine is running. I personally have not tried this, but if you do and the car reacts badly, the previously stated steps should rectifty the problem.

Both of these problems are easily avoidable with some care and common sense.