Strage ignition and dwell problem.

[AudiS2]

Hello!

Made a new engine loom last winter for my Audi S2 on vems. The engine runs perfect and car drives fine. Only now the engine misfires when running boost higher than 250Kpa. The car was running perfect on the old original loom so i checked all the wiring but everything was fine. I used a coil tester to test the coils and noticed coil 1 was a little weaker than the other 4. When i set the dwell time low (1ms) it is a lot more noticeable. So i changed coil 1 for 2 and 2 for 1 and now the coil on cilinder 2 was weak. So it seems i have a bad coil.

I made a movie off this. https://www.youtube.com/watch?v=Kz_iK7X5xvo and also on this forum. http://www.s2forum.com/forum/showthread.php?t=71275

So i purchased 5 new AEM smart coils and wiring and new MSD plug wires.

Today i placed everything on the car. So all new wiring to the coils. The new coils and new wires.

Of-course i did a new spark test and its still weak on coil 1!
I changed coil 1 for 2 and 2 for 1 to see if i have a bad coil. But the weak spark was still on cilinder 1!

So now its not the coils but the wiring or VEMS i think. I checked all the wiring and all is fine. No voltage drop and good grounds.
Also tried a other ignition output but still a weak spark.

Is it possible the VEMS gives coil 1 a low dwell and the other coils the dwell i set? Is my vems bad?

[VEMS]

Hello AudiS2,

There has been an issue with manually triggering the coils and its effective dwell, this issue has been corrected 2 okt 2013 (released around 1.2.18 firmware). If you are running any firmware version lower than this, this bug is indeed present.

However since it is only active during manual engagement of spark test (not during normal running conditions), it should not impact running engine performance.

Best regards, Dave

[AudiS2]

Hello AudiS2,

There has been an issue with manually triggering the coils and its effective dwell, this issue has been corrected 2 okt 2013 (released around 1.2.18 firmware). If you are running any firmware version lower than this, this bug is indeed present.

However since it is only active during manual engagement of spark test (not during normal running conditions), it should not impact running engine performance.

Best regards, Dave

Nice! Im running firmware 1.2.11

So its not posible to test the coils this way on my firmware? I will just take the car for a test drive than. Tanks!

[VEMS]

Testing the coils (for connection or function) is possible as you have seen; However using it as a gauge to judge spark strength unfortunately not (during spark test: index 0 will have correct dwell, all others will have enlarged dwell).

[AudiS2]

Tanks Dave! Nice info.