so he tried it and its perfect, i havnt a clue why it affects just 1 cylinder not a very good design in my mind as that cylinder must get a hiding its entire life. anyhow. thanks heaps for the advice it was rite on the money

hi thanks for your thoughts, i have disconnected it and left him to try it as i was limited on time however looking at the setup i cannot see why it would only effect the 4th cylinder. ill keep you posted.
thanks

hi all. i have a problem, my brother owns an isuzu! i noticed a couple weeks ago it was running a little ruff. next thing i knew it had a knock it sounded to me like timing or a faulty injector. i told him to crack one injector at a time and see which one if any were playing up. he reconned none so ...