hiya,

for some reason the boost pressure of my mates wrx is very low,around 6 to 7 psi (44kpa on his digital guage) on full chat.

i have checked for the obvious leaks,split pipes,etc and have still no joy. i am fitting a dawes to it next week but would like to sort out why the boost is so low before i do it.

any ideas on what to look for

and what sould it be set at,,its a 95 wrx

cheers

roy

 

I hate to go for the most obvious thing to check, but does the boost gauges connection need the teflon wrapping to seal the connection? I say this because a week ago i was getting low boost readings and sluggish needle movement wrt throttle, and i took apart the ENTIRE intake and checked every vacuum line before I realized that the gauges teflon wrap was worn through, giving poor gauge readings, even tho the connection was very tight and i didnt hear any air leaks in the cabin.
This is surely the most unforgiving manifold connection

 

6 - 7 bar is the ECU limp home level, and also the default opening for the waste gate when no boost control is in use. If a WRX saloon then should be around 14 psi tailing to 12 psi at high revs. If a wagon, lower levels circa 10 psi tailing to 6 psi.

Look for the hoses around the boost control solenoid ( on the driver side wing ) being loose / off, and check wastegate linkage in case actiator arm is siezed open / fell off!

See what you can test on dump valve in case it is opening too early and dumping a lot of boost air?

An ECU reset may help, check for error codes on the check engine light which may tell you if there is an error somewhere.
Search on here for the link to the error codes meanings / how to readthem.

 

hi all. iv got a sub impresa wrx sa station wagon. M reg 1994 its a jap import. just recently i fitted a boost gauge because it felt like the car was lossing boost. i found that the car would boost up to 1.0 bar and on full acceliratin but then back down to 0.6 bar after a secound or 2 on full acceleration in all gears. i need help in finding out what it could be.i have cheaked the acctuator with a pump and it seem s to hold preasure fine. how do u cheak the blow off valve. could that be a problem on this model?

 

If the car has a TD04 turbo, then it is "designed" to tail off boost at high revs as a safety feature ( or because it runs out of puff!)!

The turbo can't maintain the pressure as the engine uses it as revs rise, so boost tails off to a lower figure. It should hold up better in 4th and 5th though.

Not sure how to test BOV, but Jolly Green Monster posted some method on here recently.