Spark threshold and knock

[gunni]

Cliff wrote that tuning ignition (finding MBT) can be also done by finding detonation - once you hear a knock, retard 3 deg and you are good. Isnt this good enough?

No.
As there are more tables in the ecu than just the ignition table. They change the final timing and they must be tuned accordingly.

[AVP]

it is just weird because on motronic i had 20deg on high rpm and more than that on lower rpm + i was geting +3deg when IATs were below 25C or something.

and now im down to 13-14deg on middle range and slowly climbing up to 16-18deg to the red line.

Why is that? Same car, same specs, different way of determening the spark vs boost. Motronic uses load from the MAF

[gunni]

Do you have a log from the motronic showing it using this higher advance?

[AVP]

yes i do. i have done a couple of vagcom logs,although the whole thing got stuck a few times,but i managed to see that even up to 5500rpm on 4th gear pulls it went up to 21deg advance(which was pretty much the same as the map i have)

[AVP]

Next saturday im going to a garage near where i live to recheck the timing with a strobe light.I want to make sure the trigger setting is accurate,and therefore have a better idea of the timing difference between motronic and vems.

[AVP]

we tried to do a timing check today,but it was a no go,due to the coil pipes configuration on the rs2 rather than coil cables.

does anyone know an easy way to get to the cyl 1 spark plug,while still running the engine?

[PeepPaadam]

Why don't you use old spark plug wire connecting it from the coil (pipe) to spark plug? That's the usual way to use timing light with COPs.

[GintsK]

My way to check timing on 20VT is put clamp on primary coil wire. My strobe light is very sensitive in this case. Often it strobes not spark event but start of coil charging. Opening clamp by ~1mm helps to trigger on spark event.

20deg@2bar boost?! May be you have very good fuel. I had never more than 16-18deg@1.8bar. And going higher usualy require overfueling to prevent knock. It is on RON98.

Are you sure that motrnic is maped at so high air masses per cycle?

Gints

[AVP]

motronic was mapped for up to 1.9bar overboost and 1.7bar to the red line,so 20-22deg advance is with probably 1.7bar boost.However i also got aggressive ignition advance with motronic adding 2 degs when IATs are lower than 25C as well. Which is why i thought that now that i have it no more than 16deg on 2bar and 17 at 1.8bar  maybe my basic timing setting is wrong.

Also i recently got some pinging but that wasnt at high rpm,it was only during spool up and low rpm where i was getting the initial high boost.Then it cleared up as revs came up. Anyway,now that is sorted and i have reduced timing on that area plus increased fueling on higher revs to keep everything under control,but i will have to do this check.

does anyone know any cheap ignition cables that would fit the audi 20V so that i could perform that check?