A6 (C6) Starting Issues - Suggestions?

[daytonA4]

I recently purchased a 2007 A6 3.2 Quattro and when warm, starting is effortless. When cold, however, issues begin to prevail. I used to have a B7 A4 3.2 Quattro with similar issues but it turned out to be due to a severe carbon buildup in the fuel injectors and intake valves. $3600. The oil smelled strongly of gasoline which was an indicator of leaking injectors. However, my A6's oil does not smell at all like gasoline and there are no signs of a history of considerable carbon buildup. Perhaps a fuel pressure regulator issue? Battery? It begins to start fine and then the revs drop before turning over, giving the impression that it won't start at all, before surging to 1500 rpm. Oil viscosity and quality are fine.


2007 Audi A6 3.2 Quattro (C6)

[SinCityA6]

Are you hearing the fuel pump prime when you open the driver door?

[daytonA4]

Yup.

[c@@kieMonsta]

Ok, I'll take a stab at this. What is the vehicle's current mileage? Have you ever changed the fuel filter and if so, when? I had a similar issue on my '07 A4 and it was remedied with a fuel filter replacement.

[daytonA4]

It is just over 172,000 km / 107,000 miles. I got the car last Thursday so I have no idea if the fuel filter has been replaced.

[SinCityA6]

can you provide a video clip of it?

[daytonA4]

I'll see if I can.. It shouldn't be a problem.

[daytonA4]

Nothing in the way of a struggle today but it did make a properly miserable sound when starting, just before turning over.. My 3.2 A4 did the same when I had it.

[c@@kieMonsta]

It is just over 172,000 km / 107,000 miles. I got the car last Thursday so I have no idea if the fuel filter has been replaced.

Well, I would begin with that. It super easy(liek 15 minutes of actual work) and the part is only $30 or so. I'm willing to bet it's never been replaced and trust me, it's NOT a lifetime part.

http://www.europaparts.com/fuel-filt...511e-mann.html

[daytonA4]

Definitely not a lifetime part, that's for sure. I'll look into that. I think a DIY task as simple as that is about my speed.


2007 Audi A6 3.2 Quattro (C6)

[daytonA4]

**UPDATE**
I replaced the fuel filter without any issues and the car runs better when driving but it didn't fix the hard start. Might it be the battery?

[Tarrant]

Battery, injectors. How does it smell when you start it? Strong? How do the exhaust tips look? Very black?

Get a voltmeter and put it on AC and read the battery when its running - if its anything other than 0 you have a bad alternator.

[daytonA4]

Exhaust tips are spotless and there is no bad smell. Also, the oil does not smell like gasoline, so I'm led away from believing it is the injectors (THANKFULLY). As stated above, my A4 3.2 had gasoline smelling oil, carbon covered exhaust tips, and smelled a bit like burning oil when starting. That was $3600 in repairs from the fiery depths of hell. Again, the A6 has none of these symptoms. I'll have to get a voltmeter. When running, the lights and other electrical components are perfect, but the battery might not be charging.

[FormulaElement]

Do you have VCDS? A scan would help a lot.

I'm thinking carbon buildup. It should be regular maintenance every 50K miles on these cars. I know it doesn't have the same symptoms as your A4 but besides the battery there's just about nothing else it could be unless your fuel pump isn't priming when you open your door. Then it could be that.

Try turning your ignition to on for 5 seconds but don't start your car. Then start it after the wait and see if that helps.

You can also pay for a boroscope or something to assess the carbon buildup.

[daytonA4]

I don't have a VCDS unfortunately but I will try the test for the fuel pump.

[daytonA4]

Voltmeter test proved a healthy alternator (AC read 0) - the battery itself maintained >13V while the car ran though, perhaps a charging issue.

[corrado-correr]

I was told on vwvortex that a faulty crank position sensor and the wiring leading to it if pinched/fretting could cause such symptoms.

[daytonA4]

I've read about that being a huge problem with early 2000s Mercedes Benz vehicles. Certainly something to consider.

[callaghan.]

Nothing in the way of a struggle today but it did make a properly miserable sound when starting, just before turning over.. My 3.2 A4 did the same when I had it.

Mine sounds just like this. It also smokes quite a bit until its warm...and even then there's often a small bit coming out. Tips are black. Thoughts where to start??

[daytonA4]

If your tips are black I would advise looking into a carbon buildup on the intake valves and fuel injectors. Does your engine oil smell strongly of gasoline? If so, your injectors are clogged and leaking because they won't close properly. This will result in a drop in fuel pressure and difficulty starting. The dealership can take a borescope and inspect the buildup. If your injectors do in fact need to be replaced, be prepared for an ugly invoice sheet.

[Freeaudia6]

I have been having the same problems with my 4.2. Took it to the shop and diagnosed a bad lpfp. Fuel pressure would slowly start to drop when cranking. Ordered one today, hopefully it takes care of the problem.

[daytonA4]

I've found that turning my vehicle on in 'accessory mode' for a few seconds before starting seems to help a bit. I'm beginning to think it's the LPFP as well; I've heard that they tend to go. I'm interested to hear how it goes, keep me posted! What's the mileage on your 4.2?

[Freeaudia6]

It's got 138,000. I'll let you know if that solves the problem.

[daytonA4]

Thanks, I appreciate it. Best of luck!

[callaghan.]

If your tips are black I would advise looking into a carbon buildup on the intake valves and fuel injectors. Does your engine oil smell strongly of gasoline? If so, your injectors are clogged and leaking because they won't close properly. This will result in a drop in fuel pressure and difficulty starting. The dealership can take a borescope and inspect the buildup. If your injectors do in fact need to be replaced, be prepared for an ugly invoice sheet.

Injectors are good to go...no gasoline smell. I'm assuming its just carbon buildup.

[daytonA4]

If it's bad enough it can spread to the injectors quite easily, with these being direct injected vehicles. If you stop it soon enough you'll be fine though. Perhaps try a good injector cleaning fuel additive?

[Freeaudia6]

Update: new lpfp fixed all my starting problems and the p0089 code. Hope this helps.

[daytonA4]

I will definitely have to look into that during my car's next service. I'm glad it worked, and thank you for letting me know!

[maga4]

Hey all. I'm having the same issue with my 2010 3.0T with about 46k miles on it (lots of turning over before starting with cold ambient temps). Pretty sure it's not carbon (at this mileage or with this motor), no negative smells or exhaust tips indication, and I wouldn't think it was the fuel pump. It could very well be the battery (no indication if/when it was replaced as I picked it up in July with 41k miles), but would expect it to be more consistent regardless of temps.

Anyone have any insight on this? Thank you in advance!

[SinCityA6]

Hey all. I'm having the same issue with my 2010 3.0T with about 46k miles on it (lots of turning over before starting with cold ambient temps). Pretty sure it's not carbon (at this mileage or with this motor), no negative smells or exhaust tips indication, and I wouldn't think it was the fuel pump. It could very well be the battery (no indication if/when it was replaced as I picked it up in July with 41k miles), but would expect it to be more consistent regardless of temps.

Anyone have any insight on this? Thank you in advance!

I agree with you that it would not be a carbon issue. So that leaves Fuel and spark.

When opening the driver door to get into the car, are you hearing the fuel pump prime the fuel rails (sounds like a zip, zip). If this is not happening, then the motor is not getting the initial prime and is taking a little longer for the system to fully pressurize in order to feed the injectors properly.

It could be the battery/charging system not delivering enough voltage (cold cranking amps), injectors failing or bad spark plug(s).

Are you getting any DTCs when scanning with VCDS?

[maga4]

Thanks for the response, Sin. I do hear the priming when opening the door. No codes/DTC when scanned either.

To your point, I suppose that leaves the plugs, battery, charging system, or injectors. I have not felt any hesitation or anything like that when driving, so is that possibly rule out the injectors?

Regarding the charging system, does that mean the alternator? That very well may be a dumb question haha. It probably wouldn't be a bad idea to go ahead and swap the plugs either way. It seems to have no difference in starting after sitting overnight and sitting for a few days. Would that indicate that it may not be the battery, or does that not make a difference?

Thanks again!

[FormulaElement]

I wouldn't rule out carbon buildup. At this point the cause is between carbon buildup, spark plugs/coils, fuel delivery, and/or the crank position sensor.

A easy thing to eliminate would be the fuel filter. Mine was really plugged when i changed it recently and was causing my car to have a really hard time starting. Its cheap and takes about half an hour to change.


Just as a test, turn your ignition to "on" and let it sit for 5-10 seconds and then try turning it on. If it turns on quickly after that then it might be a fuel delivery or computer related issue. If it doesn't help then its most likely carbon buildup.

If you wouldn't mind posting a video of it turning on. Your definition of "lots of turning over" can be very subjective and it's normal for a car to turn over more when cold and not being driven recently compared to when it's warm and was just driven...

[SinCityA6]

Carbon buildup (though not impossible) is very rare in the 3.0t motor. If he had a 3.2 or 4.2 I would think carbon was an issue.

[maga4]

I wouldn't rule out carbon buildup. At this point the cause is between carbon buildup, spark plugs/coils, fuel delivery, and/or the crank position sensor.

A easy thing to eliminate would be the fuel filter. Mine was really plugged when i changed it recently and was causing my car to have a really hard time starting. Its cheap and takes about half an hour to change.

Just as a test, turn your ignition to "on" and let it sit for 5-10 seconds and then try turning it on. If it turns on quickly after that then it might be a fuel delivery or computer related issue. If it doesn't help then its most likely carbon buildup.

If you wouldn't mind posting a video of it turning on. Your definition of "lots of turning over" can be very subjective and it's normal for a car to turn over more when cold and not being driven recently compared to when it's warm and was just driven...

Carbon buildup (though not impossible) is very rare in the 3.0t motor. If he had a 3.2 or 4.2 I would think carbon was an issue.

Thank you for the input, Formula. Turning the ignition on (with the actual key) before turning it over seemed to operate the same. I will look to get a video, but I would say that the turning over sound is completely normal, but can take about 5 seconds (counting 'one thousand one, one thousand two, etc). It's not overly bad, but enough to make me think, "I hope it doesn't get my stuck here!" when I'm out and about.

The fuel filter could be something to try, as well as the plugs. As Sin mentioned, there really hasn't seen to be much carbon buildup on the 3.0T, even though it is another FSI motor. I would be surprised at enough carbon build up on this motor at 47k miles to cause any problems.

Thank you both - I will grab a quick video and consider either rolling with it or go ahead and replace the plugs and fuel filter. Thanks!

[A6AJ]

I've got an 06 A6 with 77K miles. I've got a similar issue when starting. I've reached out to different Audi service garages and other A6 owners with similar issues and this seems to be an "issue"with many of the C6 A6 models. I've been advised to turn the key to accessory mode for a few moments before starting the car. This seems to make starting easier, giving the engine time to get fuel where it needs to be. So far it appears to be working, even below 0 degrees.

I've heard carbon buildup cleanings can help, but it's def not a cure.

Just my ¢2.

[bobser1]

Seen this before turned out to have a small loss in fuel pressure through a dirty injector.Try priming a couple more times before starting when issue is happening,
normally this will indicate this fault..

[daytonA4]

My question is, is there any treatment ideal for direct injected engines other than giving the dealership $1000 or replacing the fuel injectors? Any fuel additive that'll work at the injectors and clean them, even if it isn't a permanent fix?