Trigger offset not the same if rpm changes

[g-snoop]

Hello,

Actually running with a MS on a 1272vw polo G40, I'm trying to set up the trigger offset with the trigger wizard tool.
The problem is that the offset is perfect at low rpm, and when I want to go higher (>2500rpm), the offset is not equal to the timing ligth reading. Difference is nearly 30°. EGO disabled, no correction.
I don't understand wich parameter is wrong on my MSQ...
The RPM input for my MS is the original four windows vw hall effect (modded with 1kohm resistor).

Anybody have an idea about the problem ?
My MSQ as attached file...

Thanks for help !

[grippo]

Your cranking rpm is 350 and you are using trigger rise, so you can't compare anything 350 and below with 2500 rpm and you can't set trigger offset during cranking either. But if you are comparing idle and 2500 and at idle your timing light advance and the PC advance gauge match, but they don't at 2500 rpm, then that is a problem. If you post a short datalog from idle to 2500 rpm and pick 2 rpms and tell me what the timing light says at those rpms, that will help figuring this out. But do this with the same msq you just posted.

[g-snoop]

Thanks Grippo,
I'm comparing the trigger offset at idle (perfect match with the gauge) and at 2500rpm (more or less 30° of difference with the gauge).
I will check this tomorrow and post a datalog as soon as possible !

[g-snoop]

Here is the datalog. (Same MSQ, EGO was enable, but result is the same as disable)

My readings:
At 750rpm: 12° on timing light, 12° on gauge.
At 2750rpm: 54° on timing light, 24.5° on gauge.

I don't know if it's important, but there is 5° of static advance (running very well with VW ECU).

[grippo]

I have looked at the data and msq and can't find anything wrong. When I get a chance I will run your msq on the bench and check the timing with a scope, but I am 99% sure that I will see a 13 deg change form 750 rpm to 2750, which is what your spk adv table calls for, not the 40+ deg change you are seeing with your timing light. You have a very simple and well tested setup.

Are you sure about your timing light. Other things I can think of: are you sure about your spark output polarity - what could be happening is you are dwelling when you should be sparking. Also, are you going by the regular spark gauge in MT/ TS or are you going by the trigger wizard ? You aren't changing trigger offset in between because the trigger wizard is telling you to are you ? Get out of trigger wizard when you do this test and just look at the normal spark gauge.

[g-snoop]

I'm pretty sure about my timing light (I tried up two differents).
The problem is that as soon as I put some boost (above 2500rpm), I've got a lot of knock immediatly. The spark map is the same as my ECU, but no knock whit this one.
I used the trigger wizzard gauge, so Il will test with the regular soon !
Concerning my spark output polarity, I'm not sure at all. I put this configuration according to some examples I found. Maybe wrong, how can I check this ?

[g-snoop]

Ok, I think you were right about the output polarity ! I change it from high to low, then approximatly recalibrate the trigger offset, and it seems to provide very good results !
I didn't have enough time to verify with timing light but, the engine runs very well (not going up and down at idle) and, that's new, this is very powerfull, without any knocking.
Thanks for your help Grippo, you put me on the good way !