hey guys, car is driving me nuts. hoping to get some good suggestions from you all.
bought stockish (only cobb intake and cobb stg1 tune) 07 sti and it hasn't run right since the day i bought it three years ago. p0304 code and idling rough within a few months of buying it. subaru replaced cyl 4 piston (cracked ringland) and rings under warranty and also machined the cylinder heads for the first time and said it was fixed. same exact issue manifested two months later. subaru dealer was super shady so i wasn't going back there. was told by a new tuning shop (specialize in subaru builds and tuning) best way to spend my money would be to put a new short block in it instead of refurbishing factory block. sat car for a year (company truck) while i saved up the money for a new block.
had shop buy brand new subaru short block and install it along with stage 1 exedy and grimmspeed uppipe. paid to have the shop send heads out to be checked by a machine shop (second time heads have been machined). new motor appeared to work fine. after 2000 miles on the brand new short block, had same issue yet again. had shop pull motor. failing leakdown test. heads sent to a new machine shop (third time heads have been machined...). pitting on exhaust valves and intake valve not seating properly in cyl 4. put everything back together and still failing leakdown in cyl 4.
engine sent to subaru for warranty replacement. they declined and i'm still waiting to hear why. now shop is saying they'll put a new piston and rings in it and it should be fine.
my question is this - did those 2000 miles i just drove screw up the actual cylinder wall? i'm not sure who to trust anymore. i've spent every penny i have trying to get this car driving the way it's supposed to and i'm afraid the shop is just going to throw a new piston in a bad cylinder (like subaru did before) and i'll be right back where i started...sans thousands of dollars. beyond frustrated. thanks for your time!