Vw pencil coils dwell settings

[nathanhardy]

I'm looking for a complete resource. Dwell crank? Max dwell and spark duration. As well as a voltage correction table I was going to run LS three coils but changed my mind they are well documented and was hoping to source the spec for the vw's

I figured they should be since they're in the manual and I'm pretty sure Volkswagen didn't change internals much with different types

[Drew442]

I was running these on a bike a while back and burning them up all the time. I wasn't able to find anything like what you're looking for back then.

You could have a look through my post history if you're just trying to stop them burning up.

Sent from my MI 5 using Tapatalk

[ArttuH]

A bit more specific coil model identification could help. There are quite many different VW coils that can be called pencil coils.

I have some data for one VAG COP coil model.

[nathanhardy]

Part number is 022 905 715D from what I know I have a pretty solid idea of max ms and duration it's really just the voltage comp table I'm looking for on theses! They shouldn't be to far off or different from any vag coil

[ArttuH]

Ok, the coil that I have measured was 06C 905 115M. Slightly different looking animal.


For that one I measured following currents with different dwell times and voltages:
12V
0.5ms - 3,5A
1.0ms - 6A
1.5ms - 8A
2.0ms - 10A

13.5V
0.5ms - 4A
1.0ms - 7A
1.5ms - 10A
2.0ms - 13A

I haven't written down spark duration but if I recall correctly it was about 1.5ms.

[nathanhardy]

I'm still learning here but that doesn't look like the correct table I'm use to seeing did you interpolate

[ArttuH]

I'm still learning here but that doesn't look like the correct table I'm use to seeing did you interpolate

What's wrong with it?

These are actual values that I have measured. Although current readings are from scope screen with relatively coarse resolution. So 10A there might be actually 9.5A or 10.4A. Based on my experience this kind accuracy is completely fine for determining suitable dwell time. For example this coil had saturation point around 11A so for maximum spark energy I would aim for 10A peak current (to have some safety margin). Based on these measurements I would set dwell at 12V to 2.0ms and at 13.5V to 1.5ms. Outside of this voltage range I would just guesstimate something. In the end it doesn't matter much if current at 10V (for example) ends up to be 8A or 12A.

[nathanhardy]

I wasn't saying there is anything wrong all I was saying is I do not know how to input that information correctly into mega squirt three pro... I have never been talked to properly interpolate things yet.

[ArttuH]

Ok, let's see how these values would turn to dwell settings.

At first you need to decide what peak primary current value you want to aim for. For this coil I would use 10A since it would produce almost maximum spark energy and still keep some safety margin. From measured values we see that this coil needs 1.5ms dwell time at 13.5V to achieve 10A primary current. So let's take this as base point and fill in 1.5ms to "nominal dwell" setting.

Then voltage correction. Measurement data is somewhat limited as I have measured the coil only at two voltages (12.0V and 13.5V) but we can still estimate something. In the "dwell battery correction" table we start by filling 13.5V and 100% on one row, for example on the second rightmost row. So this means that we get the "nominal dwell" at 13.5V. Then we know that we want 2.0ms dwell at 12V to get the same 10A current. This is 33% than our nominal dwell 1.5ms so we fill 133% on the 12V row. The rest of the table we need to estimate based on these two data points. So I would enter something like 170% @ 10.5V, 75% @ 15V and so on.

Hope this clarifies the idea.