Date: Tue, 3 Jun 2003 21:45:53 -0400 From: "Brian Dean" <BJDinNCnopsamsouth.net> Subject: 1991 Saab 900 2.1 liter non-turbo intake manifold vacuum questions ???
'91 Saab 900 2.1 non-turbo Intake manifold vacuum is 18 in Hg at idle. If I snap the throttle wide open - it drops completely to zero and stutters... sometimes shows a bit of POSITIVE intake pressure. When I snap it closed it recovers immediately. Confirmed it is not a plugged cat converter. I am thinking that the intake cam gear is off a tooth on the chain... or some other timing chain problem... possibly an ignition problem where spark is detonating a cylinder where the intake valve is partial open... any other ideas or comments appreciated ... ??? Brian