Unstable ignition

[murat]

I am trying to stobe, but there is around 3 degree variance, even if I use the ignition lock.

How can I fix this?

I am using div by 27
car is stock tigger audi rs2

[murat]

Here is the config file


http://www.vems.hu/files/muratADU/v3.3_n002005-A-2013.08.20-08.45.18.vemscfg

[GintsK]

Does your timing light is fixed to 0deg? If you use "smart" timing light with adjustable angle it calculates flash time from previous two spark events. And that cause some imprecision.
From what you trigger your timing light?

Gints

[murat]

Does your timing light is fixed to 0deg? If you use "smart" timing light with adjustable angle it calculates flash time from previous two spark events. And that cause some imprecision.
From what you trigger your timing light?

Gints

It is adjustable up to 60 degrees

I am triggering from the cable which goes to COP( I am using TFSI coils) on cyl #1

What is the best way to check my tdc value in config then??

[GintsK]

If you trigger strobe light from low voltage side there is a risk to trigger at wrong signal edge. If angle is fixed in software but strobed angle drifts as rpms rising - probably strobe takes start of coil charging as trigger event.
My timing light is this case works right if clamp is slightly opened. Or spark cable is used between coil and spark plug.

And use 0deg on strobe light - then it hopefully fires directly at spark event. Mine does. You can fix 0deg in VEMSTune by typing 0.3 instead of 0.

 Regarding VEMS. I would use div by 9 or even div by 3. More teeth [should] give more precision: less time to accumulating  error since last tooth before spark event passes the sensor.

Gints

[murat]

If you trigger strobe light from low voltage side there is a risk to trigger at wrong signal edge. If angle is fixed in software but strobed angle drifts as rpms rising - probably strobe takes start of coil charging as trigger event.
My timing light is this case works right if clamp is slightly opened. Or spark cable is used between coil and spark plug.

And use 0deg on strobe light - then it hopefully fires directly at spark event. Mine does. You can fix 0deg in VEMSTune by typing 0.3 instead of 0.

 Regarding VEMS. I would use div by 9 or even div by 3. More teeth [should] give more precision: less time to accumulating  error since last tooth before spark event passes the sensor.

Gints

will try...

ı am checking during idle, but there are some fluctuations(minor),

ı have to find a plug cable to check the high voltage side.

[gunni]

You will absolutely need to strobe from a HT lead, everything else is likely to cause issues with readings.