V8V 2011 N420 exhaust bypass valve function check
V8V 2011 N420 exhaust bypass valve function check
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Discussion

MasterBlaster

Original Poster:

117 posts

223 months

Monday 8th September
quotequote all
Hi, just fitted a remote switch for the F15/F22 exhaust bypass valves and noticed the valves do not move at all.
I’m confident the remote kit is OK, but not sure about the valve/vacuum circuit.
I don’t notice any difference in sound when I remove the fuse.
I videod the piston at startup, no movement at all.
Piston is fully extended and moves freely and not seized.
Am I Right in assuming the extended piston is in closed position?
How can I check if vacuum pump is working, any noises I can look out for? Relays?
Excited now to find out now there more decibels to be unleashed.😀


V8VS

16 posts

2 months

Monday 8th September
quotequote all
Can you move the valve actuator by hand? Exhaust valves can seize if they are not opened and closed regularly.

MasterBlaster

Original Poster:

117 posts

223 months

Monday 8th September
quotequote all
Yes the actuator/piston moves freely.

V8VS said:
Can you move the valve actuator by hand? Exhaust valves can seize if they are not opened and closed regularly.

Nigel_O

3,416 posts

237 months

Monday 8th September
quotequote all
IIRC, the valves don't do anything at startup - they are fully open until c 1500rpm. They are pulled closed by the vacuum pump from 1500-c4500 rpm, after which the open again.

The only way you're going to see anything is if you can be under the car while someone revs it past 1500 rpm (which might be a bit loud...)

On my car, when I turn the ignition on, I can hear the vacuum pump running. As soon as I press the 'loud' button on the remote, the pump stops.

Can you hear your vacuum pump running?

If its running, but still not opening the valves, I'd guess that the pipes aren't connected

MasterBlaster

Original Poster:

117 posts

223 months

Tuesday 9th September
quotequote all
Thanks for clarifying how it operates.
The rod doesn’t move at all when I revved up to around 4000rpm, but it is free to move.
I can hear several clicks in that area for about 3 seconds when ignition is on , but no pump sounds, is that correct?
Pipes are connected and in good condition.

Nigel_O said:
IIRC, the valves don't do anything at startup - they are fully open until c 1500rpm. They are pulled closed by the vacuum pump from 1500-c4500 rpm, after which the open again.

The only way you're going to see anything is if you can be under the car while someone revs it past 1500 rpm (which might be a bit loud...)

On my car, when I turn the ignition on, I can hear the vacuum pump running. As soon as I press the 'loud' button on the remote, the pump stops.

Can you hear your vacuum pump running?

If its running, but still not opening the valves, I'd guess that the pipes aren't connected

Nigel_O

3,416 posts

237 months

Tuesday 9th September
quotequote all
MasterBlaster said:
I can hear several clicks in that area for about 3 seconds when ignition is on , but no pump sounds, is that correct?
Assuming the N420 is the same as my 4.3, I’d say that’s your issue. The pump should start as soon as the ignition is switched on (before the engine is started). It’s a distinctive noise, a bit like one of those 12 volt tyre pumps. If all you’re getting is some clicking, it will probably be the solenoid that powers the vacuum pump.