Audi A6 2.4 (Same as 2.8) Misfire
 

---------------Détecter la langueAfrikaansAlbanaisAllemandAmhariqueAnglaisAra beArménienAzériBasqueBengaliBiélorusseBirmanBosnia queBulgareCatalanCebuanoChewaChinois (simplifié)Chinois*(traditionnel)CingalaisCoréenCo rseCréole haïtienCroateDanoisEspagnolEspérantoEstonienFinnoi sFrançaisFrison occidentalGaélique écossaisGalicienGalloisGéorgienGoudjeratiGrecHaous saHawaïenHébreuHindiHmongHongroisIgboIndonésienIrl andaisIslandaisItalienJaponaisJavanaisKannadaKazak hKhmerKirghizeKurdeLaoLatinLettonLituanienLuxembou rgeoisMacédonienMalaisMalayalamMalgacheMaltaisMaor iMarathiMongolNéerlandaisNépalaisNorvégienOurdouOu zbekPachtoPendjabiPersanPolonaisPortugaisRoumainRu sseSamoanSerbeShonaSindhiSlovaqueSlovèneSomaliSoth o du SudSoundanaisSuédoisSwahiliTadjikTagalogTamoulTchè queTélougouThaïTurcUkrainienVietnamienXhosaYiddish YorubaZoulouFrançaisHello everyone,

I live in France and I come to ask you for help because I have a problem on my Audi A6.

It is a 2.4i engine that is the same as the 2.8i.

I have misfire on cylinders 4,5,6 (all bank 2).

Here is what I changed :

Timing belt kit changed
I check timing multiple time (Crankshaft and both camshaft on each side)
Changed timing chain tensioner and chain on bank 2
Fuel pressure regulator
Changed intake manifold gasket
Changed head gasket on bank 2
Changed all spark plug and ignition coil
Changed all ignition cable
Changed fuel filter
Tested fuel pump relay manually

I did a compression test, ~175 PSI on each cylinder.

I have spark and there is fuel on the spark plug.

I do not understand...

Here are the errors i got with VCDS :

16684/P0300/000768 - Random/Multiple Cylinder Misfire Detected
16688/P0304/000772 - Cylinder 4 Misfire Detected
16689/P0305/000773 - Cylinder 5 Misfire Detected
16690/P0306/000774 - Cylinder 6 Misfire Detected
16538/P0154/000340 - Oxygen (Lambda) Sensor B2 S1: No Activity

When the car is cold i can start it easily but MIL is ON and there is misfire, i can unplug 4,5,6 and there is no change on engine RPM, but if i turn it off i can't start the car after i need to wait for the car to be cold.


I thank you all in advance for your help.

Sorry for my bad english.

Is the chain on right? Bentley manual is wrong on this in some issues.

http://wiki.ross-tech.com/wiki/index...ing_chains.gif

Hello my friend,

Thank you for your help !

My timing is exactly as this picture, the noth are aligned on both side :

https://cimg7.ibsrv.net/gimg/www.aud...7001d1bf40.jpg

I take the time to properly align both camshaft with locking tool.

I don't understand the "16 pin" history ?

Notch*

Ignore the notches on the head and count pins in the chains between the marks on the sprockets, like in the picture.

Aligning the sprocket marks with the notches on the head may not be accurate because of the way that the chain tensioner/adjuster works and the force placed on the cam shafts by the valve springs.

Since you used the cam locking bar and crank pin to set timing, you should be good with the belt, which further supports my theory that you are off a pin (aka half a link) on the chain.

Coming from the Alfa world I have seen this behaviour, "but if i turn it off i can't start the car after i need to wait for the car to be cold." fixed by a new crankshaft position sensor.
But if you have Lambda error why wouldn't you start by checking (Changing) that ?

This is a good point.

Here's correct cam chain roller count for my prior 2.7 A6 . I believe its same for 2.8 . I touched the cams more than I like to remember chasing misfires on both banks. Roller count obviously depends on where you start & where you end relative to the gear teeth. I've seen multiple pictures sometimes counting the roller(s) outside the teeth, thus you can get 15 or 16. Picture is worth a 1000 words. Below pics for bank 2 (left side, Drivers side US). If you changed chain tensioner, be sure you used correct p/n, as left & right sides are not same, but look alike & mount alike.
https://cimg9.ibsrv.net/gimg/www.aud...39734c0920.png

I laugh every time I see that picture. It's been around forever and have solved more issues than we can imagine. I love that it's a kindergarden rendition of the manual. Whoever created it (and I would love to know who did) obviously never thought it would become the authoritative source for cam timing, but it is. The hand drawn picture is the bible; honor it!

On my 2.7 I would suspect bank 2 ignition coil module, but this car has a new coil for all cylinders. I wouldn't expect 2 coils to both be bad on Bank 2. As noted, the timing chain link count could be off, since the Bank 2 tensioner was changed. However, if the Bank 2 problem existed before the tensioner swap, I would first log the B2S1 O2 sensor activity on VCDS. The No Activity code could even be a bad wire or bad connector on the firewall. If O2 sensor doesn't fix the issue, then on to cam chain.
My reason for this is that you might get lucky with the O2 sensor. An O2 sensor is a lot easier than having to pull the valve cover to check the chain link count.