The real cause of injector rattle?

[JTaylor2005]

See that's what I was thinking. If they are completely controlled by tiny electronic pulses having a bad earth could destroy the smaller pulses as the current wouldn't have enough umph to overcome the resistance. I have cleaned the ones I could find but they were only on the front under the air box and probably mostly for lights etc.

What other earth's are there? Also thanks for the info on the fpr as well