They just paved the streets for a new neighborhood around the block. Great excuse to use my LC. I haven't used it in a while or since my powerkit install. By accident, I left it in manual shift for the first run and it bounced of the rev limiter a couple of times in first. I assume I can't do any damage with a PDK car?

 

You will likely register range 1 over revs but not big deal. That’s why the PDK protection is there.

 

Should launch control be used in the manual position or in the automatic?

 

The rev-limiter is there to prevent damage albeit I would not get in the habit of doing it all the time. Otherwise, manual cars can exceed the redline on a missed down shift (aka money shift) but you have a PDK.

 

I've nailed that PDK rev limiter once in manual mode and all I can say it's a brutal awakening for the driver.

At least for me hitting it by total accident I thought the engine was a goner....... when you hit the limiter what does the engine actually do?

Throttle cut?

Fuel cut?

Retard timing?

 

Cuts the fuel for sure!

 

Cuts the spark.

 

if you are in manual mode and keep your foot planted all the way down, the PDK will shift automatically at max revs (kick down mode). You must have let off the gas if you hit the rev limiter.

FROM OWNER’s MANUAL:Kickdown
The kickdown function is active in selector-lever positions D and M.

• For optimum acceleration, e.g. when overtaking, press the accelerator pedal beyond the full-throttle point (kickdown).

The transmission shifts down depending on the speed of travel and engine speed.

Upshifts occur at the highest possible engine speeds.

 

It depends on the Rev Range you are exceeding. The first fail-safe by the DME is to cut spark, when in the higher ranges, it also cuts fuel.

 

Good idea to avoid the rev limiter if possible. Obvious I know.

If the computer cuts spark that sends a bunch of un-burned fuel out the exhaust. For a racecar no big deal but that's hell on catalytic converters. I think most OEMs cut fuel instead of spark for that reason, may lean out the engine a bit but saves the cats. On a side note, a clogged catalytic can cause an engine failure especially on boosted engines (due to increased back pressure).

Also, bouncing off the rev limiter does no favors to the engine crankshaft.

 

When your 991 from dead cold the ECU has the fuel system dump a bunch fuel into cylinders and cats to get them warmed up and operating as they should quickly. The cats are designed to handle this fuel dump.

On an overrev the ECU cuts spark immediately because that is the most effective way to kill engine RPMs quickly. If the overrev continues the ECU will then cut fuel as well.

 

I’m stage 4, and had similar issues until I upgraded to the Cobb PDK “aggressive torque” PDK tune. No issues now.

 

I believe this is different in a 991.2. There is no pedal position beyond full throttle like in a 991.1.

Actuating the kick-down function

The kick-down function is active in selector lever position D.

• For optimum acceleration, e.g., when overtaking, depress the accelerator pedal quickly as far as it will go (kick-down). Depending on the driving speed and the engine speed, the transmission will downshift.
  
  Upshifting takes place at the highest possible engine speeds.
  

IIRC the difference is most pronounced when you are in manual mode. Instead of the kick-down up-shifting for you, you bounce off the rev limiter. It's been a while since I did that so hopefully I'm not remembering incorrectly.