Need help with the N54 exhaust vacuum system- ISSUE RESOLVED

M

Maniac

Lifer
So after hearing some clicking from the car while moving this week, I thought, hm, either turbo waste gates or exhaust flap (again).

To whittle it down, I did the golf-t mod on the exhaust to leave the flap open permanently, so disabling it and diagnostically eliminating it from the possible source of the clicking.

I drove around, clicking gone, so yes, it looks like yet another exhaust flap is on its way out. I got home, reversed the mod.

I start up the car this morning and the flap isn't working at all.. it seems there's no vacuum (not the valve this time) so its time to take out the solenoid in the boot, which means the removal of loads of trim to get to, to see if its electrical or a leak in the vacuum hose that feeds the valve/flap. A job for the weekend.

So, it would seem the car prefers the loud mode enabled permanently. No need for an exhaust upgrade after all.
 
Did you do an aftermarket exhaust cut out or do all newer gen zeds come with them that in unaware of?
 
In the 35i there is a flap that closes for noise control on one exhaust. Vacuum actuated controlled by the ECU
 
Maniac said:
In the 35i there is a flap that closes for noise control on one exhaust. Vacuum actuated controlled by the ECU
Click to expand...

Maniac I have just got a 2009 35i so can I make the exhaust louder and if so how do I do it :thumbsup:
 
You can do it two ways, by blocking the vacuum line to the exhaust valve (just look under the drivers side exhaust tip) or unplug the solenoid which is in the boot Behind one of the boot hinge covers.

Look for golf t mod online.
 
Maniac said:
You can do it two ways, by blocking the vacuum line to the exhaust valve (just look under the drivers side exhaust tip) or unplug the solenoid which is in the boot Behind one of the boot hinge covers.

Look for golf t mod online.
Click to expand...

Ahh I thought it would be something on the idrive :) I am not good with diy bits!
 
Maniac said:
In the 35i there is a flap that closes for noise control on one exhaust. Vacuum actuated controlled by the ECU
Click to expand...

Can you tell it's the o/s pipe when it's operating Maniac, or is it too subtle and just blends in to the overall note from both pipes? Just curious is all.
 
Could you maybe pull the vac pipe off the valve at the exhaust and offer a bit of tissue paper up to it to see if there's any pull at all from the vac pipe rather than having to dismantle the boot first, at least then you'd know the solenoid is working or not? I would have thought unless the pipes come off completely there'd be enough to pull tissue paper even with a leak.
 
john-e89 said:
Could you maybe pull the vac pipe off the valve at the exhaust and offer a bit of tissue paper up to it to see if there's any pull at all from the vac pipe rather than having to dismantle the boot first, at least then you'd know the solenoid is working or not? I would have thought unless the pipes come off completely there'd be enough to pull tissue paper even with a leak.
Click to expand...

I'd expect the vacuum to be fairly high, but I take your point about a leak and tissue paper, I'll give that a go. I took off the tube right after startup (when pressure is allowed to pull the valve closed) and there's no hiss, nor feel when I placed my finger against the tube. I turned the car off and blew into the tube, which should be blocked by the solenoid and I could hear air going along the pipe which makes me think something could be split, backed up by the fact I'd heard clicking prior to doing anything, which could be weakness in the vacuum not fully holding the valve closed. I've presumably made a leak worse by fiddling. Its just a theory and I'm fairly certain there's no vacuum present, indicating a blockage, solenoid/electrical failure, or a leak. I have a bit of time this weekend, so temperature permitting I'll try to gain access. It should be simple enough to check the solenoid via a meter, as well as check for vacuum on the feed from the engine as well as the exit to the exhaust valve. If it is a leak in the part that goes to the valve, that will be exciting to fix as its all hidden behind the bumper/under the car.

Its not so loud that its an emergency anyhow, I'll just have a fiddle with the car when I get time. The whole rattly exhaust valve thing seems to be a common issue on all cars with them fitted over time.
 
The solenoid is just the switch though which will tell a vacuum pump to fire so you blowing up the pipe is blowing air through the pump which unless it's got a one way valve in which I would doubt then it would give you the impression of a leak in the pipe as the pump will have a pipe to atmosphere to pull air in right. Just a thought.
 
john-e89 said:
The solenoid is just the switch though which will tell a vacuum pump to fire so you blowing up the pipe is blowing air through the pump which unless it's got a one way valve in which I would doubt then it would give you the impression of a leak in the pipe as the pump will have a pipe to atmosphere to pull air in right. Just a thought.
Click to expand...

In this installation, the solenoid is a valve between the incoming and outbound vacuum line housed in the boot. So I'd expect, with the car running, to feel negative pressure on the inbound side. When blowing up the pipe on the outbound side of the solenoid, it should, in theory, be blocked as the solenoid valve is closed. When that opens it allows vacuum to be applied to the valve on the exhaust/silencer.
 
Maniac said:
john-e89 said:
The solenoid is just the switch though which will tell a vacuum pump to fire so you blowing up the pipe is blowing air through the pump which unless it's got a one way valve in which I would doubt then it would give you the impression of a leak in the pipe as the pump will have a pipe to atmosphere to pull air in right. Just a thought.
Click to expand...

In this installation, the solenoid is a valve between the incoming and outbound vacuum line housed in the boot. So I'd expect, with the car running, to feel negative pressure on the inbound side. When blowing up the pipe on the outbound side of the solenoid, it should, in theory, be blocked as the solenoid valve is closed. When that opens it allows vacuum to be applied to the valve on the exhaust/silencer.
Click to expand...

Yep agree with that on that installation. Points to the pump then does'nt it, as the clicking you can hear will be the solenoid acting but the pump not operating assuming the pipe is'nt split or has come off.
 
Iirc wasnt there a Few corvettes that had a butterfly valve in the exhaust? I remember a video awhile back were instead of changing the exhaust all he did was take out a fuse while it was switched to open. I believe it was completely open at a certain speed/RPM
 
Yep, thats a similar thing. I'll video mine when I get it working, its just a bit too loud in non working/disabled mode for quiet suburban streets.
 
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