Ok, as promised here is number one of my weekly series of little tests and tweaks to do to your car to keep it running nicely.
This first one came about after seeing a number of higher mileage cars where the inlet multiram system was not working optimumly. This could be felt particularly at sub 4000rpm with heavy throttle (i.e. overtaking!).
For those interested, here are some extracts from the Vauxhall college training programme notes which give some details of how the multiram works...:
V6 Multiram Operation
The multiram actuators are vaccum operated and its essential that this vaccum supply is good and consistent....this is the idea of this little test and fix!
For all those with a later (post 96/97) V6 which has the additional VAC tank mounted on the set of trumpets just in front of the alternator.
Here is something to try.....
The vac tank has two pipes, a feed and an output, the fed is the one on the right or bottom (or at least should be) which connects to a large rubber elbow piece.......
Here is the test I would like you to try.....
Follow the pipe from the vac tank feed to the rear of the engine bay where it connects to the brake servo pipe (normally via a T piece).
Disconnect the pipe here and suck on it, place your tongue over the pipe and check it holds vaccum.......
Reconnect the pipe and now remove the output from the vac tank (you can do this at the front multiram solenoid if its easier).....does it hiss for a short period or not?
If it does hiss all is good, if not, then read on!
The vac tank has a one way valve on the input so that when on Wide Open Throttle (WOT) the vac reserve is maintained (there is very little manifold vaccum at WOT), This valve sometimes fails and the above procedure tests it......
The fix is easy......take a trip to your local aquatics store that sells items for indoor aquariums and ask for an air valve (the type placed in the air feed pipe from the air pump to stop syphoning if the pump fails).
Place this in the feed to the multiram vac tank and repeat the test.....it should now hiss....if it doesn't then you might have fitted the valve the wrong way round so try reversing it.
Once done, enjoy the perkier engine response (much more noticeable on stick shifts).............
Re: A simple test and easy fix... 
