Hi does anyone have any information on a 2007 Q7 V6. When you first start the engine. Then drive there is a hesitation.Then when it is worm it goes away.I did notice that the coolant is low.Is there a problem with this engine leaking coolant in the cylinder head.Please give me any information on this if anyone is having this problem thanks

 

I've had the same problem and replaced the Knock Sensor which has helped so far but its only been a few weeks. Please let me know if you've had any luck fixing this problem.

Thanks.

 

They don't have a coolant burning problem as a rule. Have to be honest, we've never discovered where the coolant goes but they (Q7 3.6L) always seem to be a bit low at every service.

You may have deposits on the intake valves, which is a common thing. It can cause a hesitation or misfire on a cold engine. Provided there isn't any other concerns (ignition, or something like that), cleaning the intake valves helps quite a bit in most cases. Being direct injected, no fuel ever hits the back of the valves. Only air and oil vapor (from the PCV system). Over time, it builds up and messes up the intake air "tumble" into the chamber. In other words, instead of flowing in smoothly and with the designed swirl, it sort of falls into the combustion chamber and the mixture is not optimum for combustion,,,,,,,,,,which gives misfires, hesitation, maybe jerking/stumble. There's alot more to it than that, I just tried to summarize without going into a lot of physics, engine design, theory of combustion,,,,,,,,,,,,,,,,man, my head hurts now! lol