2006 B7 S4 Avant 132k mi Sprint Blue Tip - Bank 1 Misfires

[Wiggler]

Original owner, car has been well cared for, not driven very hard, and I can probably pull together pretty complete records (oil changed at least every 5k, lately more like every 2-3k), no major accidents, new headlights, top of engine gaskets and check valves, accessory belt/roller and snub mount, a few years ago, replaced a $700 power steering hose last year, rear struts are shot but I don't notice it in the ride, have done control arms a couple of times, it will need those again eventually. Some of the "chrome" on the front grill has bubbled up, which is weird. Nearly new Conti Extremecontact Sport 02s on factory 18" rims, slightly older Winter Sottozero 3s on nice looking 17" rims (older RS6 style, I think). Bank 1 misfiring now, not really driven since that started, but idle is rough. No timing codes, just misfires. Logged cam shaft adjusters and seems like they are behaving. Car is at shop where they don't want to take on a big job, mechanic said compression was low (100 vs 160) in a couple of (Bank 1) cylinders. So probably time to drop the engine and do the timing chain service. There is another local shop with an experienced Audi tech who said $7k without thinking about it too much, bigger shop with more experience with this sort of thing is XLR8 in Branford, CT, might be safer to send car there. I love the car but I am getting on (I'm 65) and want to work on cars less, so thinking to sell as-is, or do the repair and sell. Anyone interested in as-is? Probably worth more parting it out, but I don't want the bother. $3-4k as-is maybe? I am in Norwalk, CT. If anyone is interested I can pull together some photos.

[Wotans Fluch]

I recommend a picture or two.

[Wiggler]

I recommend a picture or two.

Will do this weekend. And sending car to XLR8 on Monday for a thorough diagnosis.

[Wiggler]

Will do this weekend. And sending car to XLR8 on Monday for a thorough diagnosis.

Many photos here:

https://mgb.smugmug.com/2006-S4-Avant

[Wiggler]

And sending car to XLR8 on Monday for a thorough diagnosis.

$1k into the diagnosis and still don't know what is wrong. Just misfire codes (and some unrelated intermittent O2 sensor codes) on Bank 1, compression OK, boroscope OK, removed passenger side cat and it is not clogged. Not sure what the next step is, if possible to evaluate timing issues when there are no codes without taking the engine apart?

Work associate who has some experience with Audi 4.2 and 5.2 engines thinks the problem is intake manifold flaps, which are plastic, prone to breakage, and could impact one side.

Anyone got a good guess?

[88jay88]

$1k into the diagnosis and still don't know what is wrong. Just misfire codes (and some unrelated intermittent O2 sensor codes) on Bank 1, compression OK, boroscope OK, removed passenger side cat and it is not clogged. Not sure what the next step is, if possible to evaluate timing issues when there are no codes without taking the engine apart?

Work associate who has some experience with Audi 4.2 and 5.2 engines thinks the problem is intake manifold flaps, which are plastic, prone to breakage, and could impact one side.

Anyone got a good guess?

I do not think an intake flapper would affect just one bank necessarily. All 8 runner caps are on the same flap on the same shaft and on the same actuator. to answer your cam question It is possible to do some cam position diagnosis without taking the engine out by looking at camshaft desired position versus actual through VCDS or similar but you would likely have codes and potentially a bunch of timing chain rattle if a guide failed. I had similar symptoms from a clogged CAT and looking at them you wouldn't know. The matrix at the inlet and outlet looked fully intact but I had bank one misfires, low on power and inability to achieve high rpm under load but never any codes that pointed specifically to the CATs. Pre cat material breaks down and ends up clogging the main cats. Low milage used OEM cats fixed my issues. Another quick check would be to move some plugs and coils around to the other bank and see if the misfires follow the coil. Seems like any basic shop would have done that already though in their diagnosis.

[Wiggler]

I do not think an intake flapper would affect just one bank necessarily. All 8 runner caps are on the same flap on the same shaft and on the same actuator. to answer your cam question It is possible to do some cam position diagnosis without taking the engine out by looking at camshaft desired position versus actual through VCDS or similar but you would likely have codes and potentially a bunch of timing chain rattle if a guide failed. I had similar symptoms from a clogged CAT and looking at them you wouldn't know. The matrix at the inlet and outlet looked fully intact but I had bank one misfires, low on power and inability to achieve high rpm under load but never any codes that pointed specifically to the CATs. Pre cat material breaks down and ends up clogging the main cats. Low milage used OEM cats fixed my issues. Another quick check would be to move some plugs and coils around to the other bank and see if the misfires follow the coil. Seems like any basic shop would have done that already though in their diagnosis.

Finally figured it out, manifold is blown out at the injector for cylinder 1, see photo at the link. Shop refuses to install anything but a new one at $4500 from Germany, though I think a new one can be had over here for something closer to a bit over $3k (ECS shows they can get a new one). I'll am going to see if Cars and Bids will take it as is, and in the meantime offer here at $3k (and there are used ones for a few hundred dollars). If no one wants it I am afraid it will go to the junk yard!

https://mgb.smugmug.com/2006-S4-Avant/i-S9Lp5jb/A

[88jay88]

Finally figured it out, manifold is blown out at the injector for cylinder 1, see photo at the link. Shop refuses to install anything but a new one at $4500 from Germany, though I think a new one can be had over here for something closer to a bit over $3k (ECS shows they can get a new one). I'll am going to see if Cars and Bids will take it as is, and in the meantime offer here at $3k (and there are used ones for a few hundred dollars). If no one wants it I am afraid it will go to the junk yard!

https://mgb.smugmug.com/2006-S4-Avant/i-S9Lp5jb/A

I know Audi claims they are not serviceable but you can take the two halves apart of the intake manifold and reseal with RTV then reinstall with some new intake manifold gaskets and locktite on the bolts torqued in sequence to spec. The bolts tend to back out and cause a leak. as me how I know ;) Maybe just start there and retorque the bolts. Cars and Bids or BaT will be tough on a car with any glaring issues. Otherwise it looks like an excellent example
Here is a thread showing it being split in half
https://www.audizine.com/forum/showt...-and-Read-Here

[EvoRam]

I have an intake for it.