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A few avenues to check out

New CPS's (all 4) and both TPS's breathed a massive amount of life back into my M5. Fuel scheduling management
is only as good as the eyes than provide input to the DME.

The same holds true for Vanos solenoid seals; hard, flattened seals will allow the control pressures to bypass.
Use factory, BMW seals since they are not "O"-rings in the truest sense; they are beveled on both outer sides,
plus a flat outer edge for extended contact with the mating bores.

The fuel pressure regulator and it's control vacuum source are definitely worth checking further. This manifold
vacuum source is supplied by a port on the lower flange area of the #7 throttle throttle body. This vacuum
hose, where it attaches to the port, is very likely "toast" due to its' high-heat environment. If leaking, you will
not be able to achieve full fuel pressure (5 bar or approx 70 psi) when at wide-open-throttle (WOT). I would
suggest replacing the regulator, along with all of the rubber vacuum hose segments. There is approximately
2 feet of hose from the #7 throttle body to the hard plastic line, adjacent to the area where the brake lines
come out of the enclosure, just under the driver side cabin air filter. Then another 4-5 inches of vacuum hose
at the regulator end. If your fuel pump is 90-100 K, replace it now. It's just false-economy to "drive it till
failure.

You might also consider pulling the spark plugs and taking some good close-up pictures. Post them here and
so we can get a good read on them. Then install a fresh set of plugs. I don't let mine past 25 K before I put
in new ones.

Good luck with your sorting out all the permutations.

Regards,
Alan
 
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