I'm running in my recently rebuild engine together with a brand new tranny and SPec single plate clutch.


My engine revs freely very good, nothing holding back

When driving, 1/2/3rd gear go very well, just some noise from the clutch

when shifting to 4th and 5th gear the noise somewhat increases and the engine has a hard time revving up between 3 and 4000rpm.

When engaging the clutch (keeping the tranny in 4th or 5th) the engine revs up normally.

Now, my boost is turned down for brake in, but does the ECU 'read' something from the tranny, in what gear it is (maybe for load correction?)

My bst guess is the clutch or tranny, but both are brand new and don't do anything strange in other gears.

anyone got a clue
?