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i am brand new to Audi. I have a 1999 A6 Quatro with 2.8. The engine seems to be missing at idle but not so much when on the throttle. here is what i have discovered so far and have done. At first I checked plug wires and replaced since one cylinder seemed to not be firing. This didn't help so I decided to do a compression test and found all cylinders onthe right side to be 75 psi and all the left side to be 125 psi. hymmmm. the spark plugs look much better on left than right. I found the spark plug on the cylinder that I thought had the bad plug wire was black so put new one in still no noticeable improvement except I know each cylinder has spark. then while running disconnected injector one at a time starting with right side and was not a huge differnce when unplugged but when I did this on left side the difference was real noticeable. i am now scratching head wondering whatis going on. the engine light is on. Do i have a head gasket problem or worse cracked head? the exhaust smells and coolant disappears. any thoughts on this? the right side is passenger side
 

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In 1999 no C6 models on the market. First C6's hit market 2004 ... ;)
 

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the exhaust smells and coolant disappears.
Coolant disappearing definitely suggests head gasket as the first thing to try.
 

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Discussion Starter #5
Coolant disappearing definitely suggests head gasket as the first thing to try.
PetrlDave,
I thought the same thing with the low compression on the whole side, however I am confused with all 3 cylinders down as a head gasket would typically be between 2
cylinders, I dont know about Audi
 

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Don't write it off unless you get any better ideas, but a warped head could explain loss of compression on all 3 cylinders?
 

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Discussion Starter #7
Don't write it off unless you get any better ideas, but a warped head could explain loss of compression on all 3 cylinders?
PetrolDave
I suppose you could be correct and that would explain compression equalizing. I thought if that were the case as I left spark plugs out Iwould still have gotton a lower reading on the bad hole. perhaps a cylinder leak down test would be in order?
 
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