P0304 Cylinder four Misfire

Tiny
MARZ9988
  • MEMBER
  • 1999 TOYOTA COROLLA
  • 1.8L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 130,000 MILES
I dry tested compression per manual procedure. 180psi +-5 across all cylinders with consistent pressure rise on each stroke. Replaced crank sensor, associated coil pack, new NGK spark plugs. Swapped injectors around to rule out injector issue. Fuel pressure okay. Plug wire resistance within range. Voltage output across injector wires A-okkay. No apparent oil leaks anywhere, coolant is green. I have researched this code and it is a common occurrence on these corollas with no apparent answers. I cannot seem to figure out what the problem is. On cold start up the car vibrates slightly but when it settles to low idle rpm it sounds like a Ford Model-T and the engine shakes, note the violent shaking occurs only in gear. In neutral the aforementioned are much less prominent but present. When idling the CEL remains on, when driving it flashes after a few meters and the car feels like it is struggling/hesitating. Prior to the code the automatic transmission would at times kick and jerk into gear 1st but never had a problem with it for the pas 20,000mi. I have a spare ECU but I have a hard time believing that it could be that. I'm beginning to suspect that it may be something of mechanical in nature. Any insight would be appreciated. Thanks
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Thursday, June 2nd, 2016 AT 12:24 AM

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Tiny
HMAC300
  • EXPERT
Misfires are hard to diagnose as it can be electrical, compression and or a fuel/air problem. Best thing for these is have a mechanic freeze frame it as it can be any sensor or injector messing up and causing problem. You have already dumped a ton of money in it with no results so I always recommend this for cheaper solution.
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Thursday, June 2nd, 2016 AT 7:18 AM

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