DMW96A6

I suspect that there was some sort of mis-communications within Audi when they designed the V6. I agree that normally, #1 cylinder is in the front of the engine for water cooled engines. When aligning a camshaft to the crankshaft using the mark on the crankshaft pulley, cylinder #1 it is always at TDC on the compression stroke.

With the Audi V6 however, when the crankshaft pulley is aligned with it's mark and the camshaft alignment tool is installed, then the passenger side rear cylinder is at TDC on the compression stroke and the passenger front cylinder has the exhaust valve wide open. This would indicate that the passenger side rear cylinder is #1.

It is impossible for the camshaft alignment tool to be installed any other way. It is also impossible for the crankshaft pulley mark to be in the wrong place and the car able to run.

Since there is no clear documentation to indicate official cylinder numbering, I suspect that this is because a mistake was made during the engines design where the passenger side rear cylinder was designated as cylinder #1 for timing purposes. Since this design mistake only affects where cylinder #1 is traditionally located and otherwise doesn't affect the operation of the engine, Audi decided to leave it as it is instead of going through the expense of redesigning the crankshaft and camshafts.

Here are the definitive images that prove which cylinder is at TDC compression stroke when the crankshaft pulley mark is aligned and the camshaft tool installed.

<img src="http://pictureposter.audiworld.com/88502/img_1125.jpg" />
<img src="http://pictureposter.audiworld.com/88502/img_1126.jpg" />
<img src="http://pictureposter.audiworld.com/88502/img_1127.jpg" />
<img src="http://pictureposter.audiworld.com/88502/img_1128.jpg" />

So, the correct cylinder numbering and firing order depend on whether or not you need for the crankshaft mark to align for the #1 cylinder.

Both of the following are correct:

Cylinder #1 is at TDC with the crankshaft pulley mark lined up:
--- FIREWALL ---
(1)---(4)
(2)---(5)
(3)---(6)
--- RADIATOR ---
Firing order: 1-4-2-5-3-6:

Cylinder #3 is at TDC with the crankshaft pulley mark lined up:
---FIREWALL ---
(3)---(6)
(2)---(5)
(1)---(4)
--- RADIATOR ---
Firing Order: 1-4-3-6-2-5 (as listed on the coil label)

Note that TDC with the crankshaft pulley mark lined up means that the passenger side rear cylinder is either in the compression stroke or overlap stroke. Using the camshaft alignment tool or making sure that the larger holes on the cam sprocket alignment brackets are between the camshaft bolts and the smaller holes are on the outside when the pulley mark is lined up will ensure that the passenger side rear cylindar is at TDC compression stroke. If you don't know where the camshafts are when the pulley mark is aligned, then the passenger side rear cylinder could be either in the compression (time to spark) or overlap stroke (between exhaust and intake).

DaveInSaltLake

when the DTC for "misfire in cylinder #1" (or something similar) pops up it's good know where to start looking.

DMW96A6

It would be intersting to see what cylinder the OBD lists if the engine is run with the spark plug or fuel injector unplugged from the passenger side front (assumed cylinder #1).

I haven't looked but I'll bet that the crankshaft position sensor's sensing mark is at the sensor when the crankshaft pulley mark is aligned which is when the passenger side rear cylinder is at TDC.

David

DMW96A6

I also can't find where Bank 1 and Bank 2 is documented which is needed for O2 sensor errors.

DaveInSaltLake

misfire on cyl#2 it corresponded to the label on the coils, and to the number printed on the plug wire.

I haven't looked at my 12V plug wire's closely recently. Do they have cylinder numbers printed on them?

DMW96A6

The coil label shows which wires go where showing cyl #1 is passenger side front but no cyl diagram.

MrGoodbytes

...when you take off the belt. If you set it to TDC, they may want to turn when belt tension is removed, thus screwing with your t-belt job?

DaveInSaltLake

to change out the water pump and string the new belt around all the parts. No big deal, they go right back to where they belong when the tool gets put back on.

DMW96A6

Each 1/3 rotation of the camshaft puts one cylinder at TDC compression and another cylinder at TDC overlap with the remaining cylinders at various stages of opening/closing the intake/exhaust valves.

If you have the crankshaft pulley mark aligned then the camshafts won't rotate when you remove the belt. I've had the belt on and off several times the past week while replacing the thermostat and then the water pump and now to replace the blown head gasket and never had either cam rotate when the belt was removed.

If you have the crankshaft just a little bit off center from the mark one way or the other, then the cams will move. When the cams are lined up correctly, the pressure on the lobes is "balanced".

David

4Driver4

it's that way on the 30v too.