P0300 Guidance

[GSP]

Hi all,

Car is a 2005 S60 non-turbo manual trans. 277000km

Car starts and idles with no problems. Driving at moderate throttle is fine.

During hard acceleration, the car does not pull smoothly; it’s a bit jerky but it will rev out. It does feel a little flat as you accelerate from a stop, like it bogs just enough to make it hard to get a smooth getaway with the clutch.

I only get the one generic code for misfire—no specific cylinder.

I have:
-replaced the plugs (old ones looked well-worn). No real change afterwards.
-PCV hose running up to top of head has disintegrated. But I don’t think that should impact how the car runs?? I put a glove over the oil filler, and it didn’t show any signs of the the crankcase being pressurized. Obviously I’ll replace this and service the system.
-unplugged MAS. No real change—ran the same with it unplugged.
-found a vacuum line (thin, hard plastic) from air box to intake manifold where the elbow had disintegrated. Replaced that. No change.
-I had a fuel filter, but now see that I have the “in-the-steel-tank” unit. This is a more committed step, so want to be sure I’m heading in the right direction. Thoughts on how to proceed?

[abscate]

The fuel pressure regulator goes on these cars, you are past its due date. Also the pump,electronic module or PEM

[GSP]

Thanks. I’ll start looking there.

[RickHaleParker]

• Low fuel level
  Repeated cold starting where the engine coolant temperature (ECT) has not reached normal operating temperature between starts
  Moisture in spark plug wells
  Damaged spark plug
  Contaminated or incorrect fuel
  Incorrect fuel quality (summer fuel in winter, certain markets).
  Air leakage
  Blocked crankcase ventilation.
  Damaged VVT-unit.
  Blocked / leaking injector
  Faulty fuel pressure
  Uneven compression

[jonesg]

Hi all,

Car is a 2005 S60 non-turbo manual trans. 277000km

Car starts and idles with no problems. Driving at moderate throttle is fine.

During hard acceleration, the car does not pull smoothly; it’s a bit jerky but it will rev out. It does feel a little flat as you accelerate from a stop, like it bogs just enough to make it hard to get a smooth getaway with the clutch.

I only get the one generic code for misfire—no specific cylinder.

I have:
-replaced the plugs (old ones looked well-worn). No real change afterwards.
-PCV hose running up to top of head has disintegrated. But I don’t think that should impact how the car runs?? I put a glove over the oil filler, and it didn’t show any signs of the the crankcase being pressurized. Obviously I’ll replace this and service the system.
-unplugged MAS. No real change—ran the same with it unplugged.
-found a vacuum line (thin, hard plastic) from air box to intake manifold where the elbow had disintegrated. Replaced that. No change.
-I had a fuel filter, but now see that I have the “in-the-steel-tank” unit. This is a more committed step, so want to be sure I’m heading in the right direction. Thoughts on how to proceed?

I would want to monitor fuel pressure under load.

[abscate]

PCV hose running up to top of head has disintegrated. But I don’t think that should impact how the car runs??

Missed that. That’s a massive vacuum leak which will affect running.