oops! sorry guys. I only realised i left this thread open when I checked my 'suscribed threads'
Turns out the problem was a combination of a few issues listed below:
1) the PSU I made for the CarPC was too close to the RCA inputs for the EQ. Moving the PSU further back, along with rewiring the 4g wiring I have running behind the dash, reduced the engine noise to almost zero in the front speakers but the rear speakers were still giving me some grief.
2) the rear speakers were running off cheap-o RCA's, I removed these and the fronts work perfect with little to no noise. I have still yet to replace the RCA cable with a decent low-noise one (like the one running my front speakers).
Hope this helps
oh, also. Just wanna add that I rewired my speaker (inc. RCA's) and power cables to seperate sides of the car with the spkr cables running on the side of the car that the ECU wasnt on. This helps too
