Fuel pressure q's...
'91 535i.
I'm trying to diagnose a problem where the car is hitting some sort of limit (feels like the rev limiter) at about 5600 to 5800 rpm (varies from day to day). It's also having some idle funkiness. Cold or warm starts, for the first minute or so it's fine, then idle will dip and any throttle input is bogged down and there's no power. It'll clear up after 30 seconds or so.
So far I've replaced the CPS and fuel pressure regulator.
I don't see any signs of vacuum leaks.
Hooked a voltmeter to the O2 sensor and it hovers between ~.3 and .85 volts, though it does go over 1.2v for a while after startup. Bad O2 sensor?
Checking the fuel pressure right now...
The pressure with the FP running and the car off is almost exactly 3 bar. When I cut the power to the pump, it drops down to about 2.8 bar and will stay there. Crimping the return hose with the pump on, pressure goes up to 4.5 bar.
Bentley doesn't have a test procedure for pressure in a running car, but with the car running at idle, it's about 2.5 bar. Blipping the throttle takes it up to 3. Normal? See: http://qik.com/video/1193891
30 second fuel flow, measured immediately after the (brand new) fuel pressure regulator (obviously with the car off) was .90 quarts. Bentley calls for .93 quarts. Is this enough to be a problem by the time I get to WOT and 5500+ RPM?
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