Audi A6 shootin flames:) WTF?????

[lendaddy]

My Audi A6 with the 2.7L Twin Turbo did something weird tonight. It had been sitting for maybe 1-1/2 hours and when I went to start it I heard something like a PS pump struggling then a pssst pssst and I saw light smoke from the left side??? People near by said that flames shot out from under the car with both psst's Uh WTF? Any ideas? Everything was normal after that. What the heck would be combustable under there? let alone what ignited it. Maybe they thought I was purging my NOS That's what it sounded like, only with flames. Weird as hell.

Just noticed I didnt say that the flames were from under the motor, not in the rear.

[motion]

I dunno, Lendaddy, but too bad there wasn't a democrat or two under your car when it happend.

[Weaver]

That sounds like a wastegate dumping pressure. The real question is why would there be so much raw (unused) fuel in the exhaust to cause a flame when dumping. I don't know the Bi-turbo Audi setup. Does it use integral w.gates on either turbo or one big seperate unit? Would a bad fuel injector sitting for an hour or two pass enough fuel to richen the charge so much that on the startup it would have vent pressure ?

Did it have a hard time starting?

[lendaddy]

Good questions, I am not sure. I came to the same conclusion but wondered how the fuel got in there. Thanks

[nostatic]

the 2.7T engine is pretty infamous for blowing turbos and some other issues. Maybe ask on the audiworld.com boards and see if anyone knows.

My wife's A8 has been going through a lot of oil lately, but no flames

[campbellcj]

The 2.7T uses ECU-controlled diverter valves; I don't think there is a conventional wastegate and there certainly shouldn't be raw fuel igniting outside of the car!

Searching Audiworld is probably your best bet. I can't say that I've ever experienced flames, but I have had my share of vacuum and boost hose failures. PITA and I am going to look into Samco silicone hoses.

[beepbeep]

Hehehehe...

A6 has ECU-controlled wastegates (internal) and vacuum-controlled "diverter valves", "dumps", "hooter valves", "bypass valves" or whatever people call them.

Wastegates have nothing to do with "diverter valves" and both are installed on turbocharged engines. They have completly different functions. somehow people always mix them up.

There is no "wastegate dumping pressure" during startup. Wastegate opens only under full boost and bypasses turbo, but exhausts go intor same exhaust system. With other words, it won't dump anything into outside surrounding air, not on A6 anyway.

I believe you maybe had some sort of fuel-leak that catched fire or something like that.

I strongly suggest you to takeyour car to the dealer to troubleshoot it. A6 2.7T shouldn't make strange "dumping wastegate" noises or burn underneath. It might be something potentially serious, like ruptured fuel-line etc.

[lendaddy]

Thanks Beep, I'll take it in today! Good info guys. I could leave it as is and scare the ricers at stoplights

[juanbenae]

maybe geo. w. should have looked under there fort the WMDs?