My wife owns a B7 2.0T. Short story, we leave a couple of weeks back to go to VA Beach and AFTER we left she decides to tell me that she thinks when she filled up, that the guy put in the wrong octane grade. We took my car anyways so I picked up some octane booster and figured that when we got back I'll put it in no harm no foul.

Fast forward to today, pulled it from her parking spot and stop at a light and hear a rough idle. Looked at the tach. and didn't see it fluctuate. Figured o.k lets see if it keeps it up. Sure enough I'm driving to work in it and it throws a CEL. Haven't had time to run the computer on it but I guess I'm looking for consolation. Any ideas? Hope nothing too serious. Thanks in advance.

 

While putting 87 octane gas in the 2.0T engine reduces performance (the computer will retard timing and lower boost pressure), I do not think it will hurt the car. Audi even says that the car can take 87 octane, but for optimum performance it says to use 91 or higher.

Short answer...I personally don't think that 87 should hurt your car, but maybe it has.

 

I used regular gas in my car once and the performance was not good but it did no permanant damage to my car. Could one of your coil packs gone bad?

 

I had the same thing on my 2007 2.0T twice. I would start it in the morning and it would idle rough. Also the engine light would come on for a couple of seconds. Took it to the German Audi dealer and both times it was the coil pack which they replaced under warranty. I asked the chief mechanic if this was a common issue, and he said yes. I also asked if the other two could be replaced and he said only if Audi issued a recall (which they won't).