Black smoke,missfire

[bertman]

Got alot of smoke on full boost today,really chucking it out on wot.
Not sure how to proceed as i have vag comed the car and the only fault code I got was the maf which i swapped out for a good one.That made no difference.
Also did a boost leak test and found not a whisper of a leak.
The only thing that sounds amiss is the fuel pump which after running for 10 mins or so the pump goes from a steady hum to something which sounds like a bag of hornets.
When the engine is switched off and the restarted the fuel pump sounds normal.
The car is deffo overfueling and causing alot of black smoke and a missfire on wot

[Error404]

What code did you get Rob?

[bertman]

It was getting late,and the only code or thing that came up was the maf
What would cause the pump to sound dodgy?

[bertman]

Had a play around with the car today,its started off going well and the when you get some proper temp in the engine it starts again loads of black smoke,missfire and well I pulled in back home the pump is really whining again and the engine is idling really lumpy
Switched off the engine,started again straight away,whining gone and smooth idle.
vag comed the car agin and pulled 00561,mixture adaptation-limit not reached

[DeanG]

Lambda sensor causing over fueling?

[Error404]

00561 -mixture adaptation-limit not reached means you are running rich.

Load of potential causes for this, but of course it's a classic boost leak code - you already tested that right?
As you already swapped the MAF itself, what about the MAF terminals?
I had this code caused by bad fuel pressure reg - seeing as it sounds like your pump is struggling, I might be tempted to try that first.
You can test the fuel pressure, but a new reg is cheaper than a pressure gauge to test it fuel pressure, so unless you already have one....

[bertman]

Maf terminals,are cleaned regularly.Maf swap did not cure this.
If the fpr was faulty would that cause the pump to wine like it has been doing.But shutting off and restarting seems to stop it

[Nuno_Cristiano]

I had this failure in my RS2. Check with VAG-COM ( VCDS ) in channel 1 that fuel corrections originally on idle speed need be 1.00. If maf problem you will see this value below 1.00.

In my case i open MAF sensor and a SMALL wire aluminium broken and did bad contact in terminal that connect in connector of MAF/Wireness.

[Error404]

That is just closed loop fuel trim though, not directly related to the MAF, plenty of other stuff will cause AFR to drift

[UrS4boy]

00561 -mixture adaptation-limit not reached means you are running rich. Load of potential causes for this, but of course it's a classic boost leak code - you already tested that right?...I had this code caused by bad fuel pressure reg - seeing as it sounds like your pump is struggling, I might be tempted to try that first.

Agree that the FPR could be culprit. It is conceivable that if the there is no vacuum to pull the FPR diaphragm off the outlet, there would be no (significantly less) return flow, resulting in the pressure in the fuel rail rising above the 4.0 Bar that the ECU expects when it is calculating fuelling, hence over-fueling. This would also literally put pressure on the G6 fuel pump, making it struggle. The On/Off cycling might temporarily but not permanently cure this.

Fuel Pressure Regulator info: http://forums.quattroworld.com/s4s6/msgs/21108.phtml
Fuel Pump Info: http://forums.quattroworld.com/s4s6/msgs/22623.phtml
Fuel Injector Info: http://forums.quattroworld.com/s4s6/msgs/20441.phtml

[bertman]

Well changed over the FPR with a known working one and fingers crossed the car is back to normal.have yet to go for a good thrash but first signs are promising.
So as soon as that was fixed the car decided to have no boost over than mechanical boost.I had just fitted a new N75 valve so was a bit flummoxed by that.
Quick read up on the forum and I decided to check fuse 24 to see if that had blown,which it hadn't but looked a bit old.Swapped that out and boost has returned.
So cheers Alex and Dave for the pointers.
The Fpr going **** up would explain the symptons and the fuel pump buzzing it's nuts off

[newsh]

Mmm, think I might have suggested FPR Rob [emoji6]
Was the one that failed a genuine one or aftermarket? I know you said it was recent.

[newsh]

Great that it's fixed though!

[bertman]

Looks like it was a genuine one which has been on the car 6 months or so

[newsh]

Diaphragm broken? Fuel coming out of vac pipe?