Im running a 54 sti which has had induction, full decat, fuel pump and a re-map an also a forge BOV...all of which has been done previously to me owning the car..

okay so the problem......This only seems to happing in gears 4,5 and 6 on hard boost ie. acceleratin hard on the motorway..
Although it seems to pull fine theres a chatter sound coming from what sound like the DV, if i ease off slightly then it goes

the best way i can describe it is...you hear the suckin noise from the cone filter which then turns in to a chatter sound

if anyone can shed some light on this issue or has had similar problems pls help

my location is Catterick

 

Sounds like boost surge to me. Quite common on the VF35.
you will need to get the wastegate ported.

 

cheers mate, can you explain a little more on what wastegate ported involves, not heard of that before?

 

Sorry mate, got mixed up. I was thinking off boost spike, that is when the wastegate can't get the gasses out quick enough and boost spikes higher than it should be. The way around this is too port the wastegate and male it slightly bigger:

https://www.scoobynet.com/general-te...aste-gate.html



The chattering you describe makes me think it's compressor surge. Does the boost feel like it's coming in and out?

 

Could it be the boost solonoid oscillating on and off trying to meet boost set point? or maybe boost cut?

 

no it seems like it pulls smooth but the chatter is ther...im yet to check me boost gauge to see if thats fluctuatin but ill do tha on me nxt run

 

Should be alright mate, according to Simon

 

My 3 port boost solenoid makes a noise like u describe

 

cheers for the replies...puts my mind slightly at rest knowing ppl arnt shouting at me sayin 'for gods sake DO NOT DRIVE IT!!"

wouldnt mind knowing whether to investigate further or put it down to the map??