Quote:
Originally Posted by botbs
Hi all,
Matt @ cosworth helped me a lot on the tune. However, I am on the 6th tune now and still have knocking at 5000rpm. I kind of give up because it cost me a lot for the shop flash and test again and again.
Matt noted that mt vehicle (2018 brz ts) may have a more restrictive exhaust and canadian 94oct fuel may not as good so knocking still exist.
I need suggestions from you guys, shall I ditch the cosworth supercharger and call it a day. Or shall I take the risk to buy full exhaust (header and catback)
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I am also getting a little spark knock above 5,000 rpms. Running smaller pulley on a 2016 BRZ with the Cosworth Exhaust except I retained the factory header. Eventually the ECU compensates for the spark knock but it's not entirely smooth when it does it. I noticed my advance multiplier was down to 0.43 and when I hit 5,000 rpms under wide open throttle, the car would feel a little jerky like it was climbing a stair case. I believe this is the ECU learning where the spark knock is occurring and is pulling back timing, but not smoothly.
If I reset the ECU and take the advance multiplier back to 1.0, I get significant spark knock initially when under WOT at high rpms. I'm not sure if the car is entirely happy with the smaller pulley.