addo wrote:There's your problem - someone has stuffed rags into the intake runners. No wonder it runs like crap.
But don't forget that I AM seeing a lean condition under wide throttle under load <3000 rpm as reported by the Oxygen sensor, that's why I went chasing the fuel rail pressure and fuel pump delivery in the first place.Re the fuel supply - provided your infeed pressure remained at or around 3 bar, I would not be too concerned for an idle test with the low return rate. A dyno would show you leaning out if this is the problem.
I have not re-tested for a lean condition since changing the fuel pressure regulator, but I will soon.
Lean under wide throttle won't be a vacuum leak, its either going to be low fuel pressure (seems ok, but I can't test it under full throttle load) or an injector problem, (injectors tested identically balanced last time I checked) or insufficient injector opening time due to an ECU/wiring fault or an input sensor signal fault to the ECU.
One question that I can't find the answer to anywhere, is that if I have a single cylinder misfire under load, will the oxygen sensor read false lean due to un-burnt oxygen (and fuel) from one cylinder ? I believe it will, but I can't find a definitive answer on this.
If its true my "lean condition" could actually just be a single cylinder misfire under load - exactly what I thought I had and fixed months ago...
That's not entirely true. I've tested as much as I can under load. Anything that I've replaced (such as map sensor, coil pack, spark plug leads, spark plugs etc) has by definition been tested "under load".The consistent flaw in much of your experimenting, is you're testing at situations of negligible load, for problems that start to occur under load with an engine up to temperature.
Things that I have not been able to test under (driving) load include fuel pressure, actual spark voltage to the plugs, checking for misfire under heavy load etc, and I really don't have any way to do that.
The lack of performance I'm seeing at the moment is actually worst when the engine is cold and starts to go away after a few minutes, although it still isn't great when warmed up.
The major problem is that the symptoms are just not consistent, they're all over the place, hour to hour, day to day even if I don't touch anything, as if there are are multiple intermittent faults, so isolating and identifying them is proving extremely difficult. I never know whether the change in symptoms is due to something I did or whether it would have done it by itself anyway.