Legacy TT no boost at all.

[fauxmonkey]

Hi there, this is my first post on here.

I have a 1996 Legacy GT twin turbo in manual and it seems to have no boost running through it.

it drives fine and sounds normal aside from a whiney gearbox, but i cant hear the turbos spooling like i can on my previous auto wagon and it doesn't have nearly as much pull as the auto one and usually manuals have more than autos.

I did a fault code check and came back with a few codes;

12: starter switch (which apparently is oh so common in these cars)

22: knock sensor

23: air flow meter

the air flow meter doesn't seem to be bad, it idles perfect and doesnt splutter on acceleration or anything strange like that.

I also get a 'check engine' light on solidly once the engine is running at full temperature but no other time.

So my question is this; could any of those error codes be causing my lack of boost or power? and if not, what could? im not getting error 66 which is the sequential turbo system, which is strange.

And another thing, where on EARTH does the vacuum line go for a boost gauge, firewall wise? in the auto one there was a big rubber grommet to the left and down of the intercooler but in the manual theres just a clutch fluid reservoir and i cant seem to find any suitable holes to put a line through and im not that keen on breaking out the drill.

Thanks in advance.

[Bugle]

AFM

Check light only at full temp? Unless you are only driving for 2 min at a time I'd get that looked at...

[Wiretap]

Your MAF/AFM has failed most likely. The check engine at full temp will be a faulty knock sensor probably, replace this immediately. Just because it 'seems fine' doesn't mean it is, if it's throwing a code it needs replacing.

FWIW, starter switch is usually caused by roll-starting a car at less than 5kph.

[fauxmonkey]

i just replaced the AFM and that code has gone, and the starter circuit code has vanished too. the only code remaining is the knock sensor, and if im not mistaken a faulty knock sensor causes the engine to retard by 5 degrees and cut the boost so it sounds like a faulty knock sensor is the issue.