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Hi People

Looking for possible causes or Idea's as to why my engine is leaning out at high rpm.It has a new nismo fuel pump 4.1l/m sard 550cc injectors, sard fuel pressure regulator at standard pressure, aftermarket fuel rail and after market high volume fuel filter and has fairly high hp.Any one got any idea's , some that have been thrown at me already are fuel pump not fast enough and the plenum ?

cheers Peter

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hi, how do u know that it is leaning out high in the rev's is this on a dyno? i'd be checking the tuning as it may just be a matter of adding more fuel with whatever computer ur running.. also what sort of power you making? is 550cc injectors big enough for that much power? just some suggestions. also might be worth bumping up the base pressure on the reg to say 40psi if its not already?

The Tuner, said that he was having trouble with it running lean top end and it was something to keep my eye on but on the dyno day we just had they backed of at 5300rpm because of it .FPR is set at 45psi, computer is haltec e11v2,and from all my research ! 550cc injector will flow enough for 110hp so 6 should be good for 660hp ,Only whish I had that much.

with the e11v2 u can temperely fix this by adjusting the full wide open throttle map, so when WOT is reached these values override the base map.

other than that u should put exhaust temp probes on each exhaust runner to determine which is leaning, if u find that an individual cylinder is leaning then i would look to the plenum.

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