OBW rpm

[HHO]

Hi everyone,

I just notice an interesting behavier of the engine on my 04 obw with 12700
km, when I pump the break paddle and the rpm will goes up from the idle of
around 550 to around 850 ~ 900 it will lasted for about 2 seconds and drops
down back to 550 rpm. Does that indicate something has gone wrong or is that
normal ??

Please advise.

 

[ed]

Normal.
The power brake uses engine vacuum to give the boost, pumping the pedal
changes the air flow momentarily.