hello chaps. been looking on here for a few days now, i got a zafira gsi 54 plate at weekend and on monday on my way to work noticed a flat spot at 4k which picks up again at about 4.5k.
i've read on here about disconnecting rear BCS and vac box.
i'd just like to know is this a common fault and fix and if so why is it so common i.e. what is failing?
i took the car back and its been run, tested and fault codes checked with no results or faults.
would i be ok just re-routing the vac pipes (from TB to FPR and T'd off to OE dumpvalve) or should this fault be properly diagnosed instead of being ignored?
also if it is so popular to re-route these pipes what is the purpose for the BCS and vac box?
any advice is welcome as i just wanna get it sorted as its fantastic to drive