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Knock detection when Shifting gear

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Hi Andre,

Yesterday i was busy tuning an turbo polo G40 and i was running conservative amount of ign timing 5deg

no knock detected up to 12 deg but when i change gears plex monitor detects knock.

is that due to the fact that when changing gears afr changes also slightly leaner 13.0-15.0 and it wil detect false event?

because when i run the car true the rev range no knock is detected and im using the "no rpm" preset cilinder bore 75mm gain lvl set to 20 running 98 octane fuel and atm sitting at 12 deg timing 1.3 bar of boost (street tuning).

hope u can help me out.

Cheers.

Which piston to cylinder bore clearance do you have? Maybe Plex see piston slap during shifting

It's not uncommon in some engines for the engine to suffer from what's called 'tip in knock' - Basically a brief knock event that occurs on a sharp throttle application such as after a gear change. I have only found this to be an issue occasionally, but it is something to be aware of. Obviously the first place to start is to ensure that the mid-load part of your ignition map is correctly tuned in steady state and no knock is occurring here. This is the area that the ECU is going to transition through on a gear shift so if it's over advanced then this can cause knock.

Some ECUs include a accel retard or tip in retard function which allows you to retard timing momentarily on a sharp throttle application and this will usually deal with the issue.

Thank you for the fast reply.

i will look into the mid section of the map where i see the even happing and confirm that theres no knock.

and recheck the issue.

Cheers.

We usually reply within 12hrs (often sooner)

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