Have been having a boost problem for a few weeks now and wondering if someone on here might be able to help me. The car is a 1995 WRX, stock except for CAI, axle back exhaust, few other unrelated mods. However, its EJ20 so I'm sure the problem would be similar among USDM wrx's as well.
The symptoms: Can only reach 7-8PSI in any gear, normally gets around 12-13, very obvious reduced acceleration (so I ruled out a boost guage problem). A few weeks ago, the PSI would boost to normal PSI and then after a few minutes would drop to 7PSI under load and wouldn't go any higher until I restarted the car. Now, however, the problem has got a lot worse.
Things I've checked:
First I ran the car in Diagnostics mode, gave me a normal check engine sequence, so no problem with sensors. Also, I could hear BCS clicking on test mode so assumed it is working properly.
Then, I took out air filter and checked all the vacuum lines going from wastegate to BCS and into intake, none of which had obvious damage.
Finally I tried cleaning out the ports on the BCS and plugging the hoses back in, but still no boost past 7PSI.
So, any ideas? I thought about possibly a knock issue, but can't hear any knocking plus I would assume the CEL would indicate a knock problem in diagnostics mode.