ok this is a weird one and its got me stumped. the car is S5 FC, with 6 port n/a half-bridge running an e6k. the problem is it is knocking like crazy under load. AFRs are 11-12 under load, timing is around 20-25 degrees with 15 split at full load. If i unplug the trailing coil, problem goes away and runs like normal.

The car ran perfect before the new engine was swapped in, no changes were made to the wiring

Ive swapped out four different trailing coils and get same results. I also tried setting the split to zero across the map (and retarding timing some), but still got same results. next, I looked at the trailing and trailing select signals on an o'scope and they looked good. the select (brn/yel) was a square wave, and the main (blu/yel) looked like a normal ignition signal

any ideas?

 

colder trailing plugs?

 

well its running ngk 9's in all four. i triple-checked the wiring again, i did a continuity check from the trailing connector all the way back to the ECU and it is correct. I will try to post an o'scope screenshot, but it looked alright to me

I ended up just rewired it so both L and T plugs running off IGN1 and IGN2, zero split. I retarded the timing map by 5 degrees under high load. zero problems at all, runs perfect..