Originally Posted by JimN
Can you run it at night, in the dark? You would want to remove the engine cover for this but it's more loud than unsafe (unless someone tries to stick their fingers in the belt and pulleys. Look for arcing between the plug wires- I think I mentioned them before and I would bet they're not insulating the way they should. Cross-fire will cause exactly what you're describing.
Yep, ran it in the dark, (Scary at 40mph in the dark, but know the lake and did a slow cruise down first) no arcing. Replaced the plugs, plug wires, distributer & rotor. Used dielectric grease on all joins (not contacts of course). Have also removed all earth contacts and cleaned and replaced where necessary. No Change. Fully charged battery.
PS have also replaced, map sensor, TPS, idle controll valve(faulty), injectors(buggered), temp sensors (all 3), checked earth resistance and wired new earth lead to compare - no difference. Fuel pressure is as per manual at idle, and 2000rpm -sprung a leak at 3000 but still looked good, fuel was spraying over the motor by then so no test at 4000rpm and above.