Hi! I bought my S13 10 months ago, I've a problem and I cant find the solution.
Between 1k and 4k rpm (roughly) the engine runs bad, with some misfire and bangs, if you put the fuel pressure at 3bar the engine runs without misfire and bangs.
Stock internals.
New VAG coilpack.
New Sparkplug.
New Nismo FPR (genuine).
Walbro from January.
New fuel lines.
No boost leaks or vacuum leaks.
New GT2560R.
Compression test OK, all cyl with the same compression.
Stock air filter (but with apexi had the same problem), exhaust, ecu and intercooler.
Help me!