Pulse generator contacts

Hi I'm new on here, I have a VW Type3 that is fuel injected and I have had to adjust my pulse generator contacts using the tool I made to Volker's drawing, but I am experiencing problems when trying to drive the car slowly in traffic. I have carried out lots of test on the entire FI system and ruled out all of the components except the pulse generators. The test guide on this forum says that if I measure the dwell on these contacts that it should be between 135% and165% but my dwell meter measures angle in degrees, what degree angle do I need to be achieving please?
Thanks in advance Doug.

Hi Doug,

well you should mesure in degrees 135° to 165°. of a total 360°. If you want to measure %, you should divide 135°/360° = 37,5% .However it should be more important to measure 2 equal values of a rough size like that. ECU just triggers on closing edge of contacts.

Hi Volker, thanks for the prompt reply , just to clarify with my meter plugged on to the pulse generator terminals and the engine running my dwell angle number is 45 degrees but I am on the 4 cylinder mode of the meter and am I right in saying that there are only 2 cam lobes for the pulse generators so I need to double my dwell number?
This indicates my gaps are too big but they are equal for each pair.

Doug.

Hi Doug,

just measure % or put it to 2 cylinders.

Hi Volker,
I can only measure degrees angle not percentage and my meter only goes as low as 4 on cyl numbers so do I need to double my reading?

Thanks Doug

Then just double the value your instrument shows.

Ok thanks,so that said is my result of 90 degrees on each set of contacts enough or do I need to be achieving much closer to 135 - 165 degrees and will only 90 degrees causie my driving symptom? What I am trying to say in not as many words is if I replace my pulse generator contacts will it cure my problem or are the ones fitted good enough? As my first oat states I have already adjusted them using a tool made to Volker's design but this is not giving me a dwell angle big enough.

Thanks Doug.

Hi Doug,

you made a measuring gauge with Norbert's specs, not mine. Credits should go to him. And of course we cannot jusge from here how well that was done. If it would be done well and if your trigger points would be adjusted accordingly, you would see those 135° to 165° with a dwell meter. We have also seen cases where contacts where somewhat loose and would create strange results. In the meantime I prefer to test such cases on my ignition distributor test stand.

Now the question is how much 90° instead of 135° will matter. ECU just triggers on closing contact. It does not matter how long contacts will be closed. So in practice dwell is not an issue. However 90° show that you adjusted the gap a bit wide. Try to fix it to 0.5 mm opening width on both sides. And check that it does not move. We had cases where even new trigger contacts would work one moment and cease next moment. Just beacuse the contacts plate could move.

Hi Volker, sorry yes you are right it was Norbert's design, ok I'll have a go at re adjusting them and see if I can get a dwell number closer to 135 degrees, thanks Doug.