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Old 02-01-2017, 07:25 PM   #1  
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Default 2006 A4 2.0T multiple misfires

Hi, looking for some assistance in trouble shooting my 2006 A4 2.0T
The car runs rough at low idle with multiple misfires on all cylinders. It does have lots of power while driving . The following codes listed from my scan tool (Autel MaxiDiag Elite MD802)

04248 Bank1, fuel measuring system 2, malfunction
04759 connection charger-throttle valve, pressure drop
00768 Random/multiple cylinder,Misfire detected
00769 Cyl 1, misfire detected
00770 Cyl 2, misfire detected
00771 Cyl 3, misfire detected
00772 Cyl 4, misfire detected
08825 Intake Air System Leak
01287 Idle Control System RPM Higher than expected

A little back ground info, I started having problems several months ago starting with fluctuating RPM at idle from 750 up to 20000. The symptons felt like a vacuum leak, I replaced the purge valve, no change in symptons. Then the engine started to squeal very loudly after it warmed up. I spent several weeks trying to resolve this noise. I replaced the belt tensioner, idler pulley, alternator pulley, since the car after 250,000 km never had the timing belt changed I decided to change the timing belt and water pump. After all this I still had the squealing noise, turns out it was the PVC valve. I have replaced it along with the two breather tubes and now the noise is gone, but I still have the issue with rough idle.
I purchased a new scan tool to help trouble shoot the problem, but like most things in life some times too much information is not always good. I can now monitor a lot of things but I am not sure where to start.
I did do live data on the fuel pressure and it looks fine reading 50+ bar (750 psi), then again this is what the ECU is seeing not measured.

If someone can help point me in the right direction as to what to look for.
Thanks for the help
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Old 02-12-2017, 02:17 PM   #2  
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Default Re: 2006 A4 2.0T multiple misfires

Update on my Audi, I did a full tear down of the intake manifold to get at the intake valves to de-carb them, the valve were really bad with carbon buildup and it took awhile to get them cleaned. With new gaskets and o-rings for the injectors the intake manifold re-installed. There has been a minor improvement but I still have multiple misfires and what looks to be a vacuum leak. I have checked all the lines and see no cracks or places for leaks. I swapped coils from one cylinder to the other but no change, so I can rule out the coils.
Engine runs fine at above 1000 RPM, I drove for about 150 KM with no check engine light, but within 2 min. of sitting at an idle the misfiring starts and then the check engine lights comes back on with the same codes.

Does anyone have any suggestions on what to check next? I am almost at the point where I will need to bring it to a shop for help.
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