 This is closed by a motor/arm assembly when the traction control ECU senses loss of grip/spin at the wheels.The engine was also equipped with a different throttle position sensor (six pin, as opposed to three), and a different coolant temperature sensor (which was black, as opposed to the normal light blue colour).The engines that appeared in the early 1990s also swapped the cast metal spark plug cover for a cheaper (and less regarded) plastic version.