2.3 Cylinder 4 Misfire! What else can I try?
Hello, I am in need.
I've got an 03 9-5 with 160k and a constant cylinder 4 misfire.
-Only codes are 0304 and 1304
-Misfire seems to stop at high rpm
-New DIC, plugs, new crankshaft position sensor, new vacuum hoses, new heater bypass valve
-Compression is 150-160 psi for all cylinders
-plug 4 sparked fine when I turned key with grounded plug sticking out of DIC
-Car starts up and runs reliably, just surges and shutters
-Brake booster seals well, holds vacuum/pedal movement doesn't affect idle
There is also a hissing somewhere around the fuel rail, but I didn't get any surging when held a butane torch around there.
Where do I go from here? Do injectors fail like this? fuel filter?