overboosting????
 

Hi All,

I have a 2001 bugeye wrx with a few mods ie vf35, pink inj, walbro fuel pump, blitz dual bov, aps tmic and fully decatted and of course remapped to suit.

Having issues from 3rd gear upwards as if the wastegate is pulsing and a slight hesitation:( at about 3000rpm to 4000rpm does it in 4th and 5th can be intermittent too :mad:

thought it was dirty maf but cleaned that (not sure how you can tell if it did the job though:confused:)

any ideas guys and girls????:D:thumb:

sounds like the turbo surging a bit (common on vf35) some of it can be mapped out but its a bit of a sea saw effect (the mappers on here will be able to explain this better than me) i think its the turbo takes inlet air quicker than the exhaust side can compress it, this can be played with in the duty cycle when mapping but theres only so much adj without over affecting performance of the turbo, i had it a little when i had a vf35 on my classic just lived with it!! interesting thing is i now have an sti factory fitted with a vf35 and no surge at all..

thanks for that:thumb:

would porting the turbo help/eliminate this???:wonder:

i think headers and up pipe porting does help

If you have boost creep ie where boost gently builds beyond the set target and WG duty cycle cannot control it then you need the WG ported. This is common on a VF34 and perhaps less so on a VF35. When boost is pulled in hard on a VF35 then surge is common and even a well set up the VF35 will still whisper at you in higher gears. This is more a mapping issue. As much as I want to sell you ported headers or tubular headers, I have not noticed that on their own, either of those will cure the surge problem (although you will probably have more power) without remapping. Altering the inlet tract n and changing gas velocity to the compressor turbine has a definate effect.

Hi

well just an update.

after endless thoughts i started looking into changing the dump valve as mine is very quiet imo:idea:, then happened to look on the blitz website and came across a section in the spec saying if you run over 1.2 bar you need a hard spring. I'm running 1.4 bar, ordered spring fitted and hey presto car is superb big smiles:D:D:D

so if anyones having similar problems i hope this may help

Nick

Should be lively again now Nick :thumb:

Just another reason why the std dump valve really is the best for the job :)

Should be lively again now Nick :thumb:

Just another reason why the std dump valve really is the best for the job :)