Hey Bullwinkle....i just got a tune done...I have up/downpipe, cat back 3 inch....large STI top mount IC. I have a grimmspeed 3 port solenoid and the tune seems great. But at about 1/2-2/3 throttle the boost spikes dramatically then drops, then comes back up, then drops.......It's like it's not sure how to handle adding some but not all the power. My gage indicates about 23 psi on the high side, but the target is around 20. Ideas? Sorry, don't mean to hijack the thread.
Yes, this is a thread-jack, as this is a different issue then the OP is seeing. If this is happening in 5th gear and low RPM on the highway, it is "normal." Subaru's only have one boost and wastegate map, so they typically boost higher in the higher gears. In the case of 5th gear low RPM, you are probably exceeding targets a lot, and that is causing the car to really pull down WG to stop overboost. This phenomena can be mitigated with good turbo dynamics tables, but Subaru's will always have a single "boost bounce" in the high gears low RPM areas. EDIT: Let me clarify my language here. An overboost and then bounce down to within targets (or close/slightly below) is normal. Boost rollercoastering up and down above and below targets is not (this is caused by turbo dynamics tables that aren't "flat" enough). This phenomena is easier to control with the 32bit ECU (04+ STI, 06+ WRX), but not completely removable.
Yup. A good tune can minimize this effect, but my original point was that you will always get a bit of an overboost in the higher gears low RPM areas. However, if you are getting boost "rollercoastering" (up and down and up and down), you should for sure talk to your tuner.
