Up until now we have been working on the theory that this intermitent power loss I have had since new is somehow linked to hot temps.. well, after Audi's last attempt to fix it failed, they told me to wait until the weather warmed up and we would try again ( it seems to happen less in cooler weather.. )..
A few weeks back I decided to start running her on a blend of 100 octane racing gas and regular 91 socal crap blending it to approx 93-94 octane..
The car has been pulling great and had no power losses.. until I filled up last week with Shell V Power 91 without the 100 oct.... A few minutes after pulling out of the station, with a still cool motor and cool outside temps, the beast did its trick...It resets after you restart the motor. It did this 3 times in the first 35 miles of this tankful, which also caused me to have to use alot more gas pedal to get it to move than usual.. I deduced that I must have gotten a bad tank of gas and then it hit me..
This is the exact same thing that has been happening!
So,
What component of the motor is responsible for cutting the boost and retarding the timing to this extent?
Bingo. The Knock sensors..
I ran over to Audi and verified with the tech that these sensors were indeed able to control the boost and timing and if they detect bad fuel, they will cut the power as I have been describing for almost 2 years ..The difference is that normally, knock sensors would temporarily reduce boost and timing to match the load and then return it to normal when you take your foot off ther gas..In my case, the timing and boost are retarded to minimum where they stay until you turn off and on the ignition...After running the bad gas out and having several more power cuts, I refilled with my 100+91 blend and not one hiccup since.. ( if the sensors dont have to intefere due to adequate octane and no knocking, then no problema, )
This is the first real clue as to where the problem might be as these knock sensors are really the only things in the motor that can be the culprit.. i am surprised that Audi didnt come up with this on their own having already replaced the ECU,thermostat, EPV purge valve, both MAF sensors and both exhaust gas sensors along with a few thousand test miles...
Of course yours truly had to come up with it and I'm really hopeful this is the deal.. Audi just called to ok the replacement and thanked me for being so patient..
She goes in monday.. I'll let you know how it all turns out..