Disappointing Dyno Runs Today

[cdssolara]

The guy at Curry's Auto told me he didnt know what the setting was for the knock sensor for our cars. But however... he told me I wasnt knocking according to the dyno graph. Line was smooth going all the way up to 5k. He assured me I wasnt knocking because there would be lines that squiggle up and down.

If that's the case, then it's possible that the sound from the supercharger is setting off the sensors. Some people have been guessing that this might be the case from the beginning. Keep us posted.

[shidosha01]

The guy at Curry's Auto told me he didnt know what the setting was for the knock sensor for our cars. But however... he told me I wasnt knocking according to the dyno graph. Line was smooth going all the way up to 5k. He assured me I wasnt knocking because there would be lines that squiggle up and down.

If that's the case, then it's possible that the sound from the supercharger is setting off the sensors. Some people have been guessing that this might be the case from the beginning. Keep us posted.

Sound of the Supercharger tripping knock sensors? Can you please explain how this may be? I'll have to ask my mechanic about that...interesting.

[cdssolara]

The knock sensors pick up vibrations that are due to early detonation, or knocking. Especially with smaller pulleys, the supercharger whine kicks in earlier and more often. It's possible that the OE knock sensors are detecting that sound and reacting as if the engine is knocking. This is a theory that a couple of people have come up with. I didn't really buy it at first, but now it sounds feasible if your mechanic is telling you that you're engine isn't knocking.

[EricSol]

I just tuned 2 supercharged Matrix's and they both were pulling timing from the sensors seeing detonation. The charts were smooth, the only way to see it was with a obd2 scanner.

[JoeB]

I set the knock setting before my mechanic did the dyno. I didn't want it being pushed without that correction. After the air/fuel is adjusted the knock setting should be adjusted again. Anytime you change the dynamics of your air/fuel flow it would be a good idea to re-adjust it. It is a VERY easy procedure (p. 38 of instructions).

It really works too. The S-AFC-II reads knock levels from the sensor in the same manner the OBD-II scanner reads it. Since I performed the adjustment, I haven't noticed any knocking. I always leave knocking level as one of the things I monitor. I'm not sure why but the knocking level adjustments are only made at 2 points, 1500 and 3500RPMs. -JoeB

[EricSol]

Thats common to see detonation 3500 and below. The nice thing about that is you can trim a few degrees down low and still have full timing up top. When you are really on the gas you never see below 3500 anyways. Joe the pinging at 3500 were you wide open or part throttle?

[JoeB]

The adjustment at both 1500 and 3500 RPM are set at part throttle. The adjustment procedure has you hold the RPM within 200 RPM of the target RPM and hit a button to record the setting. Are you asking because of the potential difference between adjusting it at partial and wide open? I was wondering about that myself. I know the computer does some things different at WOT. -JoeB