Poor Trigger Pattern

[dazjb]

I have my car cranking, starting and rough idling but the scope I have is not ideal. This is how it is at the moment with both primary and secondary triggers set to 'Falling' edge ...



The secondary trigger is quite near the primary trigger. Using a timing gun I can see the timing marks with this setting and have been able to set my base timing to the correct 7° BTDC by changing the 'Trigger Angle' number.

Now, when I change the primary trigger to 'Rising' the scope looks better as the secondary trigger is further away from the primary ...



The only problem like this is that the timing is way out. I cannot see any timing mark even when I adjust the 'Trigger Angle' number.

In the EMU manual it says "edges should be selected in a manner that gives the maximum distance between Primary Trigger and Secondary Trigger edges. If the distance is too small, the synchronizing trigger tooth can change at higher RPM."

These are my primary and secondary trigger settings ...




Any ideas what I should about about this?

Thanks

[RHD]

Firstly choose the PRIMARY trigger edge setting by first locking the ignition timing in the EMU settings then rev the engine with a timing light and the marks should not move, if they do then you have the wrong edge selected. (or choose the one that moves the least and adjust the delay setting until it stays perfectly aligned)

You may need to adjust the first trigger tooth number until you get your timing marks back then make fine adjustment with trigger angle. The first scope settings will still work ok the signals are not all that close together.

you can do the same with the secondary trigger but you cant check with timing light you will need to take scope reading at idle then at higher rpm and compare the position if the signals against the red lines.

[dazjb]

I have tried the things you suggested but the timing mark is still nowhere to be seen.

I will leave it as it was if you think it is fine, I was just a bit concerned the triggers on the scope were a bit close together. I took a scope whilst the engine was took to over 6000rpm and the secondary trigger was still the same distance away from the primary trigger so hopefully it will be fine.

Thanks for the help