I bought my tC2 in March 2011 and noticed that at red lights and stop signs, my RPMs sometimes go lower than 500 causing the car to have a rough idle then it stops when they go back above 500rpm. I took it the the dealer when it was due for its 5000 mile service and said that they cleaned out the overhead, which i thought was dumb for it being a BRAND NEW CAR, and was told the gas i was using from the gas stations that i use which is Valero is bad. I've never had a problem with any vehicles with this using the same fuel. I now have about 9245 miles on it and it STILL does it. Curious if anyone else is have this problem. The car doesn't do it all the time but it still does it a little too much. Thanks!

Your not the only one, my tc2 does this aswell. It seems to have a mind of its own idle wise, on a hot day starting up with the a/c on its around 2k, then as you say sitting at a light with the a/c off and the engine warmed up it can drop to around 450.

I'm glad I'm not the only one. Have you tried anything to try and stop the RPMs from going below 500? And have they worked?

i have the manual u guys with the rough idle all have automatic??

I took it in, but the car wouldn't reproduce it again, so I don't care.

i have a manual, it still does the idle fluctuation once in a while when idling and i also get rough start ups once in a while as well..

i had this problem with my 05 TC 5speed, always used 91 Chevron, but multiple stations, usually was random but the worst after disconnecting the battery. Cleaned throttle plate, replaced MAF sensor, cleaned air filter, still rough idle at lights and had to heal toe whenever sitting at a stop.....no codes and never figured out what it was...

Now i have a 2012 TC and I was hoping this problem was fixed, but after reading this I am concerned...blah

A few ways I have fixed this problem on other imports. Tiny cracks in vaccum lines. Cleaning MAF sensor. The last thing I can think to do is check the idle adj. screw on the throttle body intake. You'll need to pull the entire air box hose out to verify you are on the right screw that opens the intake butterfly valve. Make a very smal adj. Some are a counter clockwise turn to open the idle gap. All are a pain to get to as they are usually close to the firewall. Also this adj. screw has an O-ring in some cases which could be leaking.

Thanks Blackedout011TC. I will plan on doing this on my tC. Awhile back, i started using the 91 octane from the Valeros but the idling and MPG all stayed the same so I just stayed with the regular fuel. I have also notice that when i do "spirited driving" the idling starts to drop below 500 rpm at almost EVERY stop.

Do you have any modifications to the intake, or any other significant modifications to the car itself?

I have noticed mine does this too. 2012 RS7 bone stock.

I have noticed mine does this too. 2012 RS7 bone stock.

My 2011 does it too. I noticed it big time when I first disconnected the battery to install my sub. Then it kinda evened out but it still fluctuates between 450-500 RPM's at the light. Thought it was just me but I guess not :|.