I have A4 2006 2.0 Quattro. Timing issues. Belt, rollers, tensioner, water pump all replaced at 155k. Car has 180k now. Recently it has developed a lumpy idle and thrown codes for cam and crankshaft position sensors. I pulled car apart to inspect timing belt and tensioner to verify timing in front is ok. I spun motor twice from TDC and all timing marks line up. So I assume timing in front ok and not whats throwing codes. I picked motor apart and removed the timing chain cover, valve cover to inspect the tensioner and chain. I can hold the chain tensioner down off the chain and wiggle the exhaust camshaft adjuster pulley, it seems to have a lot of play. This is the part that's bolted to the exhaust cam and carries a sprocket for the timing chain. Cam does not move with it. Should the exhaust camshaft adjuster sprocket pulley wiggle back n forth when tension is released from the chain? Cam does not wiggle with the sprocket pulley the timing belt keeps exhaust cam in place. Is this play normal or is the cam or sprocket pulley possibly worn causing the slack in my valvetrain? Any advice is greatly appreciated! Thanks Shawn

 

A "lumpy" idle can be cause by the timing of one of the cams being off a tooth. It'll run fine but it's not right. I'd have it checked out regardless as it sounds like something is not right.

 

Thanks for the reply, ill be the one doing the repair regardless of how extensive it is. My question is should the exhaust cam shaft adjuster have play? This is in the back of the motor, and drives the cam chain. The cam chain spins the intake cam. I also have a delay on the exhaust cam while rotating the crank manually. Is this delay normal? I assume the delay is associated with exhaust cam sprocket and its play? All timing marks on front of motor for cam position and crank position at TDC are fine. Car has ran drove fine only noteable issue was a lumpy idle assiciated with cam and crank position sensors throwing a code. A better question is does the exhaust cam shaft adjuster have a spring in it that may have failed causing it to have play? Also is it possible to skip a tooth on the cam chain without messing with timing marks on front of motor? Thanks

 

Unfortunately I'm not going to be much help on this one as I do not have hands on experience with this particular engine. However, with as complex as some of these newer variable timing setups, I would say it is possible to get it out of time without it messing up the the timing marks on the front of the motor because the cams have their own initial setup timing marks.

I recommend arming yourself with a repair manual for this engine. Haynes makes one for these cars but while I've found them helpful in most cases, they are a little on the general side. The Bentley manuals are the factory manuals and provide a LOT more information. You can find these on eBay for around $100. Worth every penny if you ask me as it provides more information than just the engine.