My car was running great up until I changed my valve cover gasket. It was hitting 15 psi every gear and holding it. Then after I changed my valve cover gasket in 3rd 4th and 5th gear the boost oscillates between around 18 psi and 15 psi. During the process of changing my valve cover gasket my car was completely cold so it was hard to get my intake coupler to slide off my silicone inlet tube so I was dumb and used a screwdriver and accidentally poked holes in it. I chanced the valve cover gasket and put everything back together and silconed the hell out of the holes and let it set over night and reset my ecu. The next day is when I first noticed the oscillations. Figuring that the inlet was the problem I just took out my obx inlet the other day and put in a godspeed one and still hasnt changed. The mods my car was protuned on were,
Godspeed big tmic, the old obx inlet and ebay short ram, sti fuel pump, ported and polished exhaust manifolds with grimmspeed crosspipe, ebay up pipe without flex section, and grimmspeed 3 port bcs (we had to use some different vacuum line since the kit didnt come with enough I dont know if it being softer could affect this)
My car ran great for a while after the protune then I started to notice an exhaust leak noise coming from the front end and it was coming from the bottom up pipe connection, when I installed the ebay up pipe I had to use multiple gaskets to take up the space. But anyway with the up pipe leak it was only hitting 14spsi but that was still enough to beat a stage 2 cobalt ss/sc lol. Up until I bought my friends factory sti up pipe I never really got down and looked at the connection but when I finally did I looked and saw that one of the bolts must have fell out and there was only one holding it in, So I replaced the old up pipe with the sti one with new upper and lower gaskets and new crosspipe gaskets as well. Car ran great up until replacing the valve cover gasket. So I dont know if it was just funky timing that my car started oscillating immediately after the valve cover change or if having a good up pipe in there after the tune finally upset the wastegate duty cycle or if it has something to do with the bcs. Any ideas are welcome.