Trying to figure out what is going on under boost, looking for some suggestions as to how to pin point this issue before something goes very wrong. Recently as it has been getting colder outside, 20-35 degrees, and under boost, which is about 12psi stock S4 turbo, rtek1.8, under a pretty modest tune that I have not touched in a while, now under boost it has this knocking sound almost like a woodpecker or jackhammer, but its not very loud, but still very obvious and not right. I poured in some octane booster (NOS), addeded some fuel, even under 11.4 afr's, it is still making the noise. I wish I knew what spark knock even sounded like on a rotary engine, but I can't find anything on the internet! Car pulls great, but I am afraid to boost hard the second I hear this unintended noise

mods also include safc, 3" dp, no emissions, fmic, 1000 secondaries, 720 primaries.

Any advice will be nice.

 

Turn the boost down and see if it goes away. I'd also check the timing with a light and remove the CAS cover to be sure it is lined up correctly.

 

seems like your engine is having detonation/spark knock.
Do what RotaryRocket said and check the timing and set it to stock timing with the CAS.

 

checking today. just to throw another variable in the mix though, I boosted last night on the interstate in 4th and it didn't have any problems... I am going to check the turbo for shaft play as well, but I am leaning to spark knock.