Jacked a c63

Hi my 09 c63 recently started to have random RPM jumps when its in park.

I'll park the car and the normal rpms i think are around 500-700 but the car will just random rev up to 1000-1500 rpm on its own for no reason? It'll come and go come and go?

It used to never do this, anyone know why this is?


Also, second question, I have AP exhaust and recently someone told me i can clamp the valves open all the time 24/7, anybody do this before or know how to? Pics please.

Thanks

deadlyvt

Is it a constant rev up then die down than back up? If so sounds more than likely like a vacuum leak somewhere

Jacked a c63

yeah kind of,

I'll put it in park and the rpms will rev up then drop down.. then rev up then drop down constantly.

how do i check for vacuum leak?

Do i have to bring it to a mechanic or will it throw some sort of code?

last time i checked i didn't have any codes