- The FuelTech Universal 4 cylinder A harness is a great addition to any 4 cylinder build and can be used with both the FT450 and FT550 ECU’s in a complete plug and play style. It is to suit 4 injectors and 4 individual smart coils, wired in semi-sequential fuel injection and wasted spark ignition. It can be used with high or low impedance injectors; low impedance requiring the use of a peak and hold driver, high impedance requiring a peak and hold jumper harness (both sold separately). The harness is set up for either VR or Hall effect cam and crank sensors and includes 3 relays with built in fuses for main electronics, injectors and coils. The universal 4 cylinder A harness has a label for each connector and the insulation is heat, moisture and oil resistant.