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I have had random misfires on cylinder 7, took it into the shop and they did a compression test. Said cylinder 7 would be around 90 on a cold start (not sure what units that is, psi?) that would rise to 130 after the engine warmed up. The other cylinders are all above 150. I have a 2012 S5 V8 4.2L.

They also found oil in the spark plugs/coils on cylinder 7. They are saying they need to take the cylinder head off to see what’s going on, 15 hours of just labor to even figure out what’s wrong. Does this sound accurate to you guys or am I getting taken for a ride by this mechanic? It’s been an expensive year and a half for this damn car…
 

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Mate. Travel to an independent VAG guy and get yourself a second opinion. If this is true then you need the head removing and some attention, then of course a new head gasket plus the rectification work. Good luck!!!
 

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I have no compression at all on cylinder 7! ;)

Oh wait, I have a V6! :D

The V8 is renowned for carbon on intake valves, it could be something simple-ish like this. If the valves stick, they may not close properly, loosing the compression. Is the idle lumpy or any unusual noises? The cam cover gasket can leak around the plug holes, giving the oil in the plug hole.

A borescope to inspect the valve stems would be a good start. If the mechanic thinks the lack of compression is from the head or gasket, then a sniff test in the coolant can rule out a blown head gasket.

These V8s are not known for head or gasket problems, but they are with carbon in the intake which can affect valve operation, which affects the compression.
 
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