Minimum engine RPM for ignition

[stevieturbo]

Scope traces look ok ? good strong signal. The changes in height are rpm changes ( ie voltage changes )

A proper scope trace would be nice though. Yellow lines just seem to have less meaning.

Either way, they look good

[proutyc]

Had a similiar issue on a bike engine. Was informed by DTA is was more related to changes in RPM speed.

The 2 solutions offered was to increase my rotor from 24-1 to 24-2 so trigger can read or other was to go to 24v starting system. I did the 24v short term and cranks and runs great now. Will change rotor and test in few months

[harlequin22]

Thanks for the replys. What confuses me, is that it seems to not sense the missing tooth correctly when the plugs (or some) are in...

Here are the general engine settings:

general engine settings

Thanks!
Toni

btw... is the correct sensor position of great importance? I used the sensor position of the top dead center sensor that was bulid in by volkswagen. But I have no idea at what angle it is and forgot to measure when the transmission was unrigged...

[stevieturbo]

The actual position no. The position you tell the ecu it is, absolutely vital. This value must be correct, and when running you must ensure commanded timing is what is seen at the spark plug. Adjusting this figure until it is correct.

but as suggested above. If it is struggling to see the missing tooth, as could happen on some smaller wheels with less teeth, you might be better removing another tooth to make it 24-2

just means the gap is larger so it's easier to distinguish between a moment of slow cranking which would maybeshow as a larger gap and might think TDC has occured, or the actual correct missing tooth to identify TDC

[harlequin22]

I made another scope with only #1 plug in.

only #1 plug in

So, according to this scope the missing tooth is two teeth before the TDC. With a 24-1 teeth flywheel each tooth is 15 degrees. So the sensor poition has to be at 330 degrees from TDC - or am I wrong?
So i changed the general settings to this:

general settings actual

I had a RPM signal while cranking an i had a ignition on plug 1 (with all plugs except 1 in).
But after I put plug 1 in and cranked again... RPM signal lost and no lightup...
Again I took plug 1 out and tried again but the RPM signal seems lost to whereever...
And (i think) because of this no more ignition. Any ideas?
Thanks for your help!
Toni

[Wally]

Sensor position is Before TDC, so should be 30 BTDC not 330 ATDC.

Wally

[katana]

Sensor position is Before TDC, so should be 30 BTDC not 330 ATDC.

Wally

What you've written above is the same - 30 before is 330 after in 1/2 a cycle.
But in the 720 degrees of one engine cycle, the two are significantly different
in relation to Cyl #1 firing. I'm not versed enough in interpreting the different colour bars to say what is what though - sorry!

[proutyc]

As I said above and Stevie commented to.

Its not seeing the trigger when all four are connected and it is likely to be as mentioned. Wire starter to 24V and try. If you look at the scope you will see large difference in height between the lines. These height Allan told me show fluctuation in cranking speed.

[lumley32]

if its a vr sensor then move it closer to the rotor, this will increase the voltage at low speed.

[harlequin22]

Thank you all for the answers! If the yellow lines are really RPM changes, that would explain why it does not find the missing tooth correctly. Since the missing tooth is quite close to the TDC there is a big change in RPM due to the compression (which is seems pretty good due to new pistons and cylinders). And because of that the times between the teeth are all pretty different so it won't find the missing teeth and won't give a reliable RPM signal. I guess...
So, what I will do now is to make it 24-2 and see what happens then. But before that I will check the sensor again. Thanks
Toni