Technical Information K-Series Engine Ground
With K-Series engines, especially with engine swaps or situations where the intake manifold has been removed, it is important to ensure there is a good ground connection between the ECU and the cylinder head / engine block.
It is very important that the ground from the wiring harness to the engine (G101) makes good electrical contact with the cylinder head. Otherwise the return path for the sensors, ignition and VTEC may be through the ECU case to the vehicle body, which may damage the ECU and/or programmable board inside the ECU.
The recommended position for the engine ground is on the stud attached to the cylinder head. While the stock location on the intake manifold will usually work without problems, the stud on the cylinder head provides a better electrical connection.
Programmable ECU Insulation
Owners of the K-Series programmable ECU prior to serial #260 may wish to further insulate the programmable board. Programmable ECUs with a serial number greater than #260 will have insulation between the ECU lid and USB connector and do not need to do anything.
Place electrical tape or a non-metallic sticker on the ECU lid so that the lid is insulated from the USB connector. This will ensure that in the event of a bad electrical ground, no damage will occur to the ECU and/or programmable board.