H-Dev grounding kit
This grounding kit can help smooth out engine idle and give better throttle response.
To judge whether the grounding kit would make any difference we chose to measure the signal from the air flow meter at the ECU (in the passenger footwell) and also the noise present at the throttle body, with the engine idling. I’ve got a laptop based oscilloscope that we used to record the signals.
First we took some measurements of the air flow meter signal at the ECU and voltage at the throttle body without the additional grounds. Results below. We then added 4 grounding cables – 2 cables from the battery ground body connection to the inlet plenum and the front of the engine at the same point as a loom earth. And 2 cables from the left hand side of the engine to the body. Pictures below.
We were really surprised to see that the additional grounds did reduce the noise at the AFM and throttle body quite a bit. Also, I’ve driven the car and it does seem smoother when coming on and off the throttle in the lower gears.
Kit is available in red or black