My 02 WRX has the stock turbo but a catless up-pipe and high-flow downpipe. I am running a midrange tune (not too aggressive, about 220 whp) and it has been very solid for 4+ years. However, the last month or so, my peak boost level (which I most often hit in 4th gear at about 4000 rpm) has been varying a lot, from 13.9 PSI to 18.1(!) as measured by a digital gauge that keeps peak pressures.

I expected a CEL and lots of angry lights when I hit that 18, but no drama at all; I had the radio off at the time and while it is tough to hear the motor over the APS exhaust, I did not hear any detonation. I expected it to pull timing at the ECU but it has shown no signs of that, and really if you get detonation bad enough to cause the ECU to pull timing you would get a CEL, right?

Anway, bad turbo? Bad wastegate? I am getting no smoke or power loss, just random boost levels.

EDIT: I should not that this is an ECUTek software tune, no manual boost controller.

 

If you were running higher than stock boost levels for an extended period of time, id check the boost control solenoid, if its still stock.

 

Yeah I will look into that, definitely. Obviously since this is the stock TD04 I should not be seeing boost creep (though I should note I have an STI intercooler and upgraded silicon Y-pipe and Inlet hoses).

I've been fooling around with this a bit more, and I have a nice, very long and straight acceleration lane on to the highway that I hit every single day. I can do a zero-to-80 at full throttle without any chance of injury to anyone... so far I hit 13.9, 12.7, 15.6, 16.1 and then 14.7 as recorded by the peak meter... VERY inconsistent, those should be much closer together.

 

Those really arent bad, although I'd expect to see a 14.xx in second gear. I thought your variation between 13.9 and 18.1 as stated in the OP was in the same gear...

 

Yeah, I saw both of those in 4th gear. In the 0-to-80 runs I am short-shifting 2nd a bit and getting to third early, because with the 5MT, second gear is just absolutely torqueless mush.