Some times the installed valve height is too high after valve jobs, and on start-up the lifters hold the valves open. Could this be the reason that the ecno gauge isn't reacting right? M.B. offers smaller shims for the correct lifter position. I would be happy to send cranking time info (ie:4sec) being normal.
MERCEDES BENZ MASTER GUILD TECHNICIAN
ASE MASTER TECHNICIAN
27 YEARS M.B. TECH