While getting a tune there was an issue where I was not getting enough fuel in the upper rev range. This also causes a delayed start issue with the RMW Dominator cam - starts completely fine if i give it a little gas while the engine is turning, otherwise its random if it starts on the first try. I'm thinking it's either in the injectors (Bosch 550cc's from ebay) or the fuel pump/filter.

I started by taking a base reading of my fuel pressure at the fuel rail:

Key on/engine off - 52psi
Engine on/Idle - 44 psi
Rev and hold at 6k - 40 psi (quick spike to 50 psi before settling at 40)


I replaced the fuel filter then measured again:

Key on/engine off - 52psi (up to 60 if I prime the fuel pump a few times)
Engine on/Idle - 45 psi
Rev to 6k and hold 41 psi (spike to 50 psi before dropping and holding at 41)

Should it be dropping to ~40 PSI while revving that high? Is the idle PSI too low? The Bentley manual has no listed ranges other than 3.5bar while the engine is running, which should be ~50.8 +/- 3psi.

I'd appreciate any ideas

 

Who was doing the tune as would think they should know what the pressure should be.

 

I have no idea what pressure variations are normal at different RPM and load. Crappy for Bentley to left out a useful range. Did you buy the proven 550cc Bosch injectors, or did you just go by 550cc?