Flutter noise

[Ryan s3]

Had the cambelt changed today due to a leaking water pump, also found a hose which had snapped (routed by the steering pump resevouir)
A breather of some sort which was repaired at the same time.
Car has now a flutter noise when coming off the revs.
Seems a bit down on power now as well ??
Any ideas??

 

[NoggyAnton]

Have you checked the vacuum lines around the inlet and the diverter valve?

Could be a boost/air leak especially as the fluttering could be the fact the diverter valve isn't connected up properly. If it's not plumbed in it won't be working. The fluttering could be the excess boost pressure in the pipes that's not being redirected back into the intake pipe when you let off

 

[Ryan s3]

Thanks for the reply, makes sense as it goes to boost then goes a bit flat after 3-4 rpm.
Just weird after the cambelt was changed

 

[NoggyAnton]

Thanks for the reply, makes sense as it goes to boost then goes a bit flat after 3-4 rpm.
Just weird after the cambelt was changed

There's a fair amount of stuff to remove even doing a cambelt change so it's possible.
Do you have vcds or gave you scanned for any faults?

 

[Ryan s3]

There is code to do with the n75 boost valve - open circuit ?
I have found that wiring going to it is damaged but not broken, I have some bare wire showing.
Could this be my problem ??

 

[Ryan s3]

 

[Ryan s3]

2 codes still stored
Controll valve boost pressure n75 open circuit p1548
Boost pressure controll valve n249 mechanical malfunction p1200

 

[NoggyAnton]

Hi mate.
Ross tech shows this
..
17956/P1548/005448 - Boost Pressure Controle Valve (N75): Open Circuit
Possible Symptoms

• Irregular behaviour
• Loss of power
• Limp mode

Possible Causes

• Wiring and/or connections faulty (short circuit)
• N75 faulty

Possible Solutions

• Check wiring and connections
• Check / Replace N75

17608/P1200/004608 - Boost Pressure Control Valve (N249): Mechanical Malfunction
Possible Symptoms

• Malfunction Indicator Light (MIL) ON
• Power Loss

Possible Causes

• Boost Pressure Control Valve (N249) faulty
• Diverter Valve faulty

Possible Solutions

• Check / Replace Boost Pressure Control Valve (N249)
• Check / Replace Diverter Valve

Wiring like that won't help.
Check you have a 5v olat the plug. I believe that's what should be showing.

Seems odd they have both flagged up.
Was the car OK before it went in?

 

[Ryan s3]

Yep, completely fine. Water pump leaking. Only reason for change.
From first start after, got the chatter.
Changed DV today with the standard and exactly the same.
Gonna repair wiring and change the boost controller.
Thanks for the reply

 

[NoggyAnton]

Yep, completely fine. Water pump leaking. Only reason for change.
From first start after, got the chatter.
Changed DV today with the standard and exactly the same.
Gonna repair wiring and change the boost controller.
Thanks for the reply

Just thinking about this on the way to work...


The DV doesnt appear to be working as you have fluttering on decel.
Both the n249 and N75 are showing faults and they are quite near each other....

Just a stab in the dark here.

I can't check this on mine as I have done the n249 delete, but do the plugs fit if you swap them over? I believe they are both two pin mini timers....

I'm wondering if the fault is there because the ecu is not recognising the signal rather than an electrical issue.... If that makes sense

 

[Ryan s3]

Ok thanks, so just switch over the plugs and see if it makes a difference ??
Thanks for the reply

 

[NoggyAnton]

Ok thanks, so just switch over the plugs and see if it makes a difference ??
Thanks for the reply

I'd have a look and see if it's possible with the wire lengths that they could have been mixed up.

As I said its a stab in the dark. I don't think it's that but it seems odd.
From memory the n249 plug is wrapped and runs along the cam cover with the coil pack wiring

Have you got a volt meter to check the wiring?

 

[Ryan s3]

I'd have a look and see if it's possible with the wire lengths that they could have been mixed up.

As I said its a stab in the dark. I don't think it's that but it seems odd.
From memory the n249 plug is wrapped and runs along the cam cover with the coil pack wiring

Have you got a volt meter to check the wiring?

Ok, I will check both, good shout.
I will check the power source

 

[<tuffty/>]

Get a smoke test if you can... assuming that you still have the N249 all plumbed in its not unusual for all those pipes to have split from being disturbed during unrelated remedial work...

N249 fault code is because the ECU has attempted to cut boost using the N249 system and hasn't seen the boost drop quickly enough so assumes that the DV is not working... hence the fault... this is fairly common issue with people that have done the N249 bypass and have not had the relevant maps lifted to keep the ECU happy...

Open circuit on the N75 will just mean you have no boost other than actuator pressure... fairly common for the wiring to fail on these... Bill just fits a new plug...

'Chattering' I am assuming is a kind of chooo, chooo, chooo noise as you lift off... this will almost certainly be down to the DV not opening... the reason its not opening in either because the DV is faulty (OE ones can split the diaphragm) or because its not getting enough or any vacuum to open it...

If you still have the N249 plumbed in then its most likely the hard plastic pipes around the valve that have split

<tuffty/>

 

[NoggyAnton]

Get a smoke test if you can... assuming that you still have the N249 all plumbed in its not unusual for all those pipes to have split from being disturbed during unrelated remedial work...

N249 fault code is because the ECU has attempted to cut boost using the N249 system and hasn't seen the boost drop quickly enough so assumes that the DV is not working... hence the fault... this is fairly common issue with people that have done the N249 bypass and have not had the relevant maps lifted to keep the ECU happy...

Open circuit on the N75 will just mean you have no boost other than actuator pressure... fairly common for the wiring to fail on these... Bill just fits a new plug...

'Chattering' I am assuming is a kind of chooo, chooo, chooo noise as you lift off... this will almost certainly be down to the DV not opening... the reason its not opening in either because the DV is faulty (OE ones can split the diaphragm) or because its not getting enough or any vacuum to open it...

If you still have the N249 plumbed in then its most likely the hard plastic pipes around the valve that have split

<tuffty/>

Odd it's all happened after a belt change. That's what I don't understand. Guess these cars like to develop yet more faults when they are worked on. Mines done that god knows how many times this year....

 

[Ryan s3]

 

[Ryan s3]

Be this little git then !!!

 

[NoggyAnton]

Be this little git then !!!

Bingo...

One of the first things I did was replace the vac lines for silicone. Worth doing mate.

I'm now working my way through the boost pipes

As @<tuffty/> touched on, a vac leak like that would have caused both the drop in boost and the loss of operation of the Dv.

 

[<tuffty/>]

Odd it's all happened after a belt change. That's what I don't understand. Guess these cars like to develop yet more faults when they are worked on. Mines done that god knows how many times this year....

The pipes go brittle from heat... fine if not touched but as soon as you breath on them they fail...

Seen this more than a few times although most cars tend to have the N249 bypass by now

<tuffty/>

 

[NoggyAnton]

The pipes go brittle from heat... fine if not touched but as soon as you breath on them they fail...

Seen this more than a few times although most cars ten to have the N249 bypass by now

<tuffty/>

One of the first things we did on mine when I mapped it. Tidys up the cam cover area massively

@Ryan s3 if you intend to keep the car, check the breather pipes when you're there under the Inlet as well as these will give similar issues

I replaced mine earlier this year.

You can do a simplified breather system too and run a catch can if you wish

 

[Ryan s3]

I've just repaired the pipe and it's still making the same noise.
Got an n75 valve being delivered today and probably going to look in to n249 bypass

 

[Ryan s3]

 

[Ryan s3]

Thank you as always guys !!!
Pipe under inlet was split, car pulling like a train and no more pigeon noises.
Well happy !!!!
Want to give it wash and clean now but I'm blady freezing !

 

[Ryan s3]

Car felt awesome the 1st time I took it out, traction controll coming in 1st and 2nd gear. Felt so much quicker than ever before.
Today felt a little flat, no traction controll coming in and it was wet ?
With all the problems I had, i asked tps for n75 valve and received n249 but fitted it anyway and made no difference to the surging i was getting.
I'm thinking that my n75 may be tired.
I mean how quick should it be??
Felt awesome yesterday, just a bit dissatisfied with it today.
No codes stored today but did have faults related to n75 yesterday