Cold start problem
 

Hi folks, my allroad takes a couple tries to start in the morning, then when it does turn over it runs very rough for about 30 seconds. Then it runs fine for the rest of the day. No OBDII codes. I thought it was the fuel pump (voltage at the tank connector, didn't hear pump running) so I changed that out with no improvement.

Thanks for any help!

This was pretty normal to the Audi B8 OR B9. My friend has B9 and having same problem. I have Audi A4 and sometimes I also noticed the rough bounce right when I start my car. Have you check your car to dealer or ask about this?

I brought it into my mechanic. He ran a fuel system cleaner thinking it might be a leaky injector, but now he suspects an issue with coolant temp sensor. He has replaced the sensor but the dash gauge is still reading inconsistently, so there might be an electrical issue elsewhere. Hoping to get it back today, he said if he can't figure it out, he won't charge me.

id start by doing a stage 0, changing spark plugs, coils, ect

I think it might be electrical issue . I hope your car will be ok after checking by mechanic.

Mechanic replaced the coolant temp sensor (that I had replaced with OE 3 years ago because the plastic clip broke and the sensor popped out like a champagne cork) and it solved the problem.

Sounds good. congratulations....

The saga continues...So the car died on a long uphill highway grade on a hot day. It would start, but stalled again after a hundred yards. This resulted in a $750 tow into town and driving my van 2 hours to rent a Uhaul trailer with a bad tire...another 3 hours on roadside. The next day it started and ran fine.

My mechanic and I blame the cheap fuel pump I put in...He replaced it with a VDO, lesson learned...assuming it solves the problem. I'm still dealing with the brake light problem, which may or may not be related (it certainly is oddly coincidental).

thank you for thread