Fuse 22: way to check its all working?

[marknash99]

Since fitting the 200cell cats the bloody car is soooo loud. On cold start up its too much, neighbours won't be my best friends. I've put the fuse back in and I'm not sure it's made a difference. How can I check if the valves are working? Can you see them?

[MadMacMcMad]

Check your fuse.
I have a fused switch on mine with the full BR cats/manifolds etc upgrade and the difference with switch on / off is very obvious. Sounds like a Nascar when off and very smooth and properly baffled when on.

[Neil1300r]

It's designed NOT to work on cold startup, valves should be open.

[bogie]

cold start is noisy regardless

go for a drive there should be a noticable step change in noise at 4 k revs if the fuse is in and working...if noise is the same through the rev range just changing pitch then flap is open

[marknash99]

Just took it for a drive with the fuse in, no obvious change in noise a 4k

Any idea what sort of thing could cause them to stop working?

[shuzzy]

Had this with my DB9, could never actually tell any difference with fuse 22 in or out. In the end got the car on a ramp and realised the vacuum pipes to the valves had been disconnected and the valves were always open regardless of fuse. Decided to just leave them disconnected as the louder the better as far as I'm concerned.

[V8V Pete]

marknash99 said:

Just took it for a drive with the fuse in, no obvious change in noise a 4k

Any idea what sort of thing could cause them to stop working?

The valves can seize open when car is left with Fues 22 out for a long time. One of mine was when I had the 3-way switch fitted last year at Burleigh. The BR guys fiddled for a couple of minutes under the back of the car and sorted it. Total cost for fix and 3-way switch - £50 donation to charity!

So solution is to get a 3-way switch fitted (other AM specialists are available) and use the car in quiet mode once a month to stop the valves seizing again.

My new SP10 has the sport button which opens valves at lower rpm but will still get a switch fitted as I just don't really like the artificial transition when valves open/close.