Phildodd06

Whats going on??

Just recently, when i floor it duin about 100 in top gear my boost goes round to 1.4 bar, and some times if i let off i get like a thump as if i have hit a brick wall.

Has this got anything to do with the cold weather we have had recently?

pimpalicous

i should imagine the thump is u hitting the boost cut yeah boost does increase with colder weather should be stopping it before it gets to that point though i had this when i had a chip installed it was fine in summer then when winter came it over boosted and hit boost cut the map was mapped to run to close to the boost cut out so when winter came it couldnt stop the boost in time i know there is a three port prodrive solenoid u can buy which i believe helps sort this or a boost controller.or it could be ur wastegate is sticking or is broken. hope this helps

im sure some peeps will post who know alot more than me not hard!

WRX Blues

I agree - the thump is definately fuel cut as it used to happen in my MY97 STi! Eventually fixed my problem by fitting Blitz DSBC with max setting of 1.25 bar.

rikroe666

mines running at 1.4 but i have full exhaust with no cat. Think it needs a re-map as i havn't had one done yet. not sure bout the thud though, mines never done that. Do you have any mods?

Phildodd06

Mods are :-
3" zorst full system
Decat pipe
Green cotton pannel filter
PRB7 spark plugs
Oil catch tank witch VTA
Runnin on V power
Car not maped

Alan Jeffery

Steady mate, or it won't last until you do get it mapped!
Without knowing your model or year, It doesn't sound like you have anything fitted to make that boost, so it could be accidental. Possible split wastegate hose or split actuator diaphragm.
Whatever, it needs looking at, so don't go ragging it about.

172sport

iTrader: (6)

I've hit boost cut too, I'm thinking its the weather just sooo cold and damp.

20withascooby

ive also starting hitting a brick wall over last few days in 4th gear only

StiX

iTrader: (4)

I have had this recently, but it was exactly as described above - a split hose. The actuator wasn't doing its job due to the leak, and it was boosting through the roof.

Mine has been mapped to 1.25bar and it was going up to 1.4-1.5bar. Actually hit boost cut on the motorway.

Fixed two split ends of hoses on the solenoid, but somehow missed the one on the turbo nipple which was also suspect. Fixed that and now all fine - WOT, hits 1.25bar and goes no further.

Justified the recent installation of my boost gauge

Phildodd06

Its a Version 5 WRX STI Type-R 1999
Where is the wastegate hose and actuator diaphragm?? ill have a look.

StiX

iTrader: (4)

Have a look at this, helped me loads:

How Subaru's Factory Boost Control System Works v1[1] 01

Good diagram on here explains it well.

Phildodd06

Cheers

Glowplug

iTrader: (8)

Yeah had boost probs on my recently aquired MY93, fitted boost gauge, only boosting to 0.5, knackered solenoid, got that sorted, then overboosting and fuel cut, next changed ALL boost and vacuum plumbing, probs sorted all for about £50.
Donnot fit MBC until you have sorted the under laying problem, the MBC will only mask the fault not cure it.

All thanx to this exellent forum i might add. Thankyou.

Turbo virgin learning fast!