Rev hang on gear change

[PaulH]

Hi, My 2005 95 Wagon 2.0t manual, petrol, lhd with 175k Kms (110k miles) has an annoying rev hang problem on gear change despite new vac lines, DIC, TB, BPC, Plugs & stage 1 remap by Noobtune with modification to eliminate rev hang. Karl advised me to check TB o ring, cable tightness, 1 way valves & Servo. On removing vac line from inlet manifold & blocking feed in manifold it ran without hang, reconnected & disconnected line from charge pipe & blocked feed, ran without hang but at least this way I have brake boost so have left it this way. Can’t blow air through lines towards booster but can suck a bit. Does this suggest a new valve or Servo. Strangely the fitted Servo is OEM 5231154 but all my research for a replacement indicates 5390844. BTW the brakes are fine. Any comments very grateful.
Paul

[sgould]

Welcome!

Saab only used one servo unit for cars from 2002-2010. That is one for RHD cars and one for LHD cars.

The number you quote 5390844 is for LHD.  The RHD number is 5390851

Where did you get the 5231154 number.  It's not listed in the Saab parts list.  If you read it from the part itself, it may be a "sub part" that is used for part of the servo and the part number quoted in the parts list is for an "assembly".

When you changed the vac pipes did you change the short one that runs between the inlet manifold and the fuel pressure valve?  It's often missed.   Other things that can cause air leaks are failures in the non-return valve(s) in the fuel venting system.