Date: Tue, 14 Dec 2004 00:45:09 GMT From: "James Sweet" <jamessweetnospamail.com> Subject: Re: 99 Turbo update - vroom vroom
> > > > It's a _very_ abrupt cutoff; maybe I'm just hitting the rev limiter. Need > > to try again tonight and see what RPM it's happening at; I was watching > > the boost gage rather than the tach. > The 99 fuel cutoff is really just the fuel-pump being switced off. I don't > know how that feels since I don't have that feature, but I would think not > quite as abrupt as total ignition misfire. The rev limiter is supposed to > cut in at 6000 rpm and as far as I can tell from design, it will stay out > until the rpms have dropped substatially. 6000 rpm is way beyond where I > shift up and I have never experienced that. It is a simple spring-loaded > centrifugal device in the distributor, quite easy to disable just for the > sake of ruling out that possibility. It could be that the spring is getting > old. Your original post indicates that it is boost related, not RPM. > > Volvo used a fuel pump overboost cutoff, at least on the 240 and 740 Turbo models. I've hit it before and it's very abrupt and unhealthy sounding as you describe this one. The boost was set too high after replacing a turbo, floored it and WHOOOSH *BANG* WHOOOSH *BANG* it's really amazing how quickly boost can build up, it's *very* difficult to regulate it with the accelerator pedal.