adoroshuk10

I have a 2009 Q5 at 55,500 miles with questionable engine performance (V6 3.2L). Sometimes (not always) when I start my Q5 the starter keeps turning and doesn't have the momentum to turn over to start the vehicle. However, when it keeps turning over and I press on the gas peddle, the car retains momentum and starts. Also at times, when I'd be driving I would have jumpy(jerks) performance at low RPMs. I was once at a stop sign and the car just stalled all together. I recently replaced the spark plugs and fuel pump (under the hood) and the problem still persists at times.

I was wondering if any of you, fellow Audi owners had any similar issues and had any resolve? Thought I'd ask before I take it to the dealer.

Thank You much Audi family

plat27265

What's your mileage? Based on your Q5's model year, I am guessing your problem might have something to do with carbon deposits behind the intake valves.

adoroshuk10

im currently at about 55,500 miles

rdA4WtQ5

If you only have this issue when the vehicle is warm it may be leaky fuel injectors passing fuel when the vehicle is off. The car is in a too rich condition to start until you add peddle adding air. Have you added fuel injection cleaner (Techron)? Sometimes that can help. Any check engine lights? especially after a stall?

adoroshuk10

I havent added Techron yet. I will have to look into that. Regarding check engine lights, none are on, even after the stall. which is why im a bit hesitant to take to dealer, because i have no check engine light on, and i dont want to spent dealer $$$ for something they wont be able to diagnose in the first place because of no check engine light.

raj99

Also before you go full bore into assuming it's carbon build-up. Why don't you get a VCDS and pull codes. Then actually capture a video of what exactly is happening upon start-up and post it here for all to see and more importantly hear.

Lastly, the issue could also be fuel related and when was the last time you changed the fuel filter on the car? Also, there might be an issue with the HPFP (high pressure fuel pump).

newmoon

I'm going to copy and paste my response for you too because your case also sounds similar:

Maybe check the crankcase pressure regulating valve. There is actually an "Emissions Service Action 17F9" for the 2.0T engine, because the diaphragm in the valve may tear. They replaced just the diaphragm in my 2012 A6 2.0T preemptively under warranty, but it actually did not seal properly and caused symptoms similar to what you experienced:

- engine very difficult to start
- stumbled very badly trying to maintain idle
- acceleration from a standstill was very poor and almost felt like it would stall, but mine never actually stalled
- my check engine light did come on after 1 day

So the dealer had to replace the whole crankcase pressure regulating valve assembly and the problem was resolved.

The diaphragm is supposed to close most of the way when the intake manifold vacuum is high, like at idle. If it doesn't close properly, then excessive unmetered blow-by gases will be drawn into the intake causing a lean mixture and misfires.