Golf GTI L4-1984cc 2.0L DOHC (9A) (1990)
![background image](/volkswagen/golf_gti/l4-1984cc_2.0l_dohc_(9a)/Page-312002.png)
reduce the volumetric efficiency of the engine and thus reduce the manifold vacuum level.
NOTE: The ignition timing will also affect the manifold vacuum levels, verify the timing is correct prior to measuring the vacuum.
If the after-repair vacuum level is lower than the pre-repairs level this would be an indication that the timing belt may not be installed correctly.
NOTE:
-
The vacuum checks should be made at similar engine speeds and temperatures.
-
Check "manifold vacuum" at a source downstream of the throttle plates.