I had been reading thru this topic few times now trying to get a grip. I have some thoughts to share.
First, talking about tuning new car for WI. It has been mentioned that you want AFR about 12.5 as cars under boost run normally richer. Well here is a third gear pull of my car. It?s totally stock:
AUDI 2002 model 1.8 Turbo
Max boost hit early about 7PSI@2000RPM. After 4500RPM there is boost reduction due to turbocharger going outside efficiency range at the same time AFR seem to be becoming richer. This does not correspond with max torque band as it is 2500-3500RPM.
Look like new cars run lean stock. My cruising AFR is 14.7@ light load(80Km/h)
Second, according to stock ECU knock sensor reaction KNOCK been detected throughout whole RPM range. Under knock I mean not audible knocking but early knock detection by ECU(mild knock). Here is Correction Factor data log:
CF1,2,3,4- timing pull back by ECU due to high knock sensor activity.1-cylinder number one and so on.
BTDC ? ignition advance.
You can see as CF goes up ECU pulls ignition down. This present equally thru whore RPM range not just thru max power band. This would mean that WI have to be active thru whore RPM range. During normal cruise there is no CF noted. It only appears under the boost and can vary from during whole RPM range to showing up here and there. There is no consistency in knock. Looks like it is very unpredictable but load dependand. It is also noted that poor fuel quality will make it more intence as well
Any comments anyone?