Hello,

Recently (since my last fill up) my 2.7T A6 has been performing poorly. I had about 1/4th of a tank of gas and it was fine. My girlfriend was going skiing so I filled it up with premium (as always) at a Petro-Canada station. I use them or Shell as they are the only stations around that meet Audi's fuel recommendations. She picked up her sister and hit the highway for a 2 hour drive there and two hour drive back. All highway. She said she never noticed a problem but she was cruising at 110km not accelerating. Since she has returned, the car seems sluggish. Its missing a lot of punch between 2,000rpm and 4,000rpm. I find myself stepping down on the accelerator more than usual to overtake people. I had to gun it to get in front of an F350 which was flooring it to prevent me from getting in front of him at a merge and I barely got in front of him, embarrassing. At one point, when in tiptronic mode 3rd gear, I stomped on the gas and the rpm needle started moving and seemed to hang for a second at 3500rpm before continuing up. Like it "hiccupped".

My thought is that I got bad fuel at my last fill. I am not getting any knocks or anything but from what I understand there is a sensor that prevents that. I am concerned its the turbos going but my A6 was purchased 3 months ago and is Audi certified. Plus I would think dying turbos would create a far more pronounced problem.

Can anyone tell me if this is what I can expect from bad fuel or might there be a more serious issue? The car does accelerate fairly fast if I floor it, its just the normal torque punch is lacking. I’m thinking the gas station screwed up and hooked regular fuel to the premium line. Only noticeable issue is performance, no odd sounds or rough idling etc.

Thanks for any advice you guys can give me.

 

"only stations around that meet Audi's fuel recommendations"

Like what?

There could be a number of things I could think about:

- any DTC
- gasoline quality - what is the average consumption?
- any smog from the exhaust
- tip is adaptive - just drive - gas-brake-gas-brake - it would change its behavior.
- fuel filter plugged

 

I think your paranoid. Like nemohm said I believe your transmission adapted to your girlfriends more relaxed driving style. It will adapt back.

 

Thanks for the reply nemohm.

Audi sent me this nice little pamphlet soon after I bought the car. It had a whole speal about gas quality etc etc. Then they listed companies that meet their quality recommendations for fuel. Petro-Canada and Shell were the only canadian oil companies on there so I only use them. As for your other questions:

No DTC
I avg about 14 L/100km in the city, 11.0 L/100km on the highway (the car got 10 L/100km on the highway this time with the current talk of gas)
No smog from the exhaust
I would hope the fuel filter was not plugged, pass Audi inspection 3 months ago. Since then I have put 1,500 kms on it.
As for the tip, I have "Sport Mode" on it and even in that mode its performing poorly even though its shifting like it should and normally does in Sport Mode

Anyways, there is definatly something wrong. The girl takes the car all the time and I have never had this problem. Hell, even she complained about how it was driving once she got off the highway. Even in "Sport" mode I have to push the car to get it to perform like normal.

If it does have 87 Octane in it, what are the symptoms? I remembered after my first post that right after I filled it up last I did notice a little sluggishness when I floored it but nothing when driving normally. Now that its down to 1/4 of a tank, its half asleep it seems. If there is 87 octane in it is there any harm in driving it down to near empty before I fill up again?

 

10 L/100km is quite an achievement.

87 octanes are ok to drive going skiing (Lake Louise?)
City driving is NOT suggestable!!!

If the ECU compensates for the 87 - retarding the timing would have effect on performance as described.

Just fill with higher octane gas (94) or use a bottle of octane booster.... temporarily..

(The fuel filter takes 30min for replacement)

 

I have the same model. Two quick things that I would do would be to check your air filter and make sure nothing is obstructing the intake (prior to the filter). The other thing that I would try would be to add some fuel additive (octane boost and/or fuel system cleaner).

 

nemohm:

Wow that’s bizarre. Yes, she went skiing to Lake Louise. So she, thankfully, burned off 4/6th of the tank on the highway going 110km (she never speeds).
The ECU retarding the engine does seem to make sense to me. I doubt it would seem handicapped to anyone who had not driven it before. I suspected as much being that the poor performance was not accompanied by any other issue. I suspect gas because last time I filled up, the pump beeped when I picked up the pump handle, as if I had made a fuel choice. Then I had to press the premium button about 3 times before it got selected. I think the pump had it out for me and was intent on feeding me 87 octane. I found the improved fuel economy very odd. Then I read a post on the boards about someone who noted that they got better fuel economy in 2.7T using 87 octane...which I would never choose to do personally but that post does further support the fuel theory.
94 Octane? Where can you get that? I don't recall ever seeing any stations in Calgary carrying it. Any benefit to using 94 Octane all the time? I'm not chipped or anything but if it won't hurt and give a performance boost I may try it.
If I can find out where to get 94 Octane I will try that ASAP. If not, I may just drive it like a baby (or let the girl drive it everywhere) until it uses up the rest of the suspect fuel. I have about 100km worth left in the tank (about 1/5th)…any risk in doing that? I don’t want to screw anything else up by adding Octane booster to a near empty tank.

Thanks for your help nemohm, much appreciated.

 

It was the fuel. Fixed it. Had 1/4th a tank, put in 1/3 of a bottle of octane, and filled it with shell v-power 91 octane.

The turbos are blowing way louder; performance is back to normal, if not better.

My mechanic at the dealership told me never to use 94 octane from stations in Calgary because it has ethanol. He said they use 94 octane non-ethanol fuel in Europe and that’s optimal. To bad we can’t get it here.

Also, never get gas from the Petro-Canada in signal hill, Calgary. They sold me 87 octane at 91 octane prices. Facists.

Thanks everyone for your help.