Originally Posted by JimN
Did someone remove all of the plug wires at one time? Verify the firing order and base timing (you need to put the ECM in 'Diagnostic Mode" for this (you can use a paper clip, inserted in terminals A and B of the diagnostic harness plug, then raise RPM to 1000).
Thanks JimN, yes we have checked the firing order and the leads are correct. We have had to adjust the timing as per my first post to dial out the pinging low down but it brings the backfire / misfire lower down the rev to 4100, advance the timing increases the pinging but backfire and misfire higher up at 4500rpm.
Then just to be difficult some times it does not do it at all......
Fresh fuel as well!
Also read on other posts this week how to set base timing and will buy a timing light and test tomorrow.