ign advance - configuration or measurement problem ?

Car runs fine. If advance is forced (terminal command) to 10deg, it is 10deg. But when forced 20 or 25deg, it really is 25 or 30deg.

Here's how it went:

For 15 crankdeg ignadv command change (10..25), measurement shows appr 30 crankdeg change (1..30).

Our first guess was that something misconfigured, eg. for 2 cyl. But I couldn't spot such problem. Eg. RPM constant is 3000 (12000/4, so looks good for 4 cyl):

So it is kindof likely that using wasted spark, your smart strobe light gets confused. We've seen that happening (yes: a dummy light is often better - harder to get bad readings). Consult the the timing light userguide to investigate this.

Yes, I thought that too, but i have been measuring with this (Snap-On) tool for ages, never had any such problems before. It is a known fact though, that with this lamp, you cannot get sensible reading with advance selection at 0deg. It has to be 1 or more. I have measured dozens of VAG cars with this, including my own cars former setup with MS-Extra. I will check this anyway, maybe build a dumb-light from a bright led.

Assuming info on refcard.pdf means, mdaxx = force advance xx units, where 1 unit means 0.25deg. So 0x28 equals 10deg, 0x3c equals 15deg, 0x50 equals 20deg. => exactly. More notes:

0x50 = 5 x 16 = 80 => 80 x 0.25 = 20 deg. True.


Bought cheap dummy timing light. I also draw more markings on crank pulley to help. This was very strange, because the other light has worked perfectly with other wasted-spark systems.