Misfires/ studders anytime the car goes below 1200rpm. Coil packs? Water in the fuel?

[Bobcdn]

I have a 2007 A4 2.0T, 6MT, S-line, TI, Avant. No modifications to the motor.

'It's so cold here right now that I seen a dog frozen to a fire hydrant on my way to work' - old dumb joke... but it is really cold -17 C or 1.4 F.

Car drives normally, but if you let it come down to idle 1200rpm or so, the car starts to mis. I feather the gas and it revs up fine- and if I rev it up a few times and let it come back to idle it will idle normally.

My first thought was coil pack(s)- but there is no check engine light? So then I started thinking about water in the fuel- as the tank was low ( I filled it up). Another thought was a weak battery- but then the I thought the ABS light would be on if the battery was that weak.

So what do the experts think?

[APR_Fast]

A misfire doesn't necessarily throw a CEL but could store a soft code. Scan for codes and report back.

[Bobcdn]

Unfortunately I don't have anything to scan it with.

[APR_Fast]

in that case, coils and plugs can be a common culprit of misfires and they're relatively cheap and easy to fix especially if they're old. i'd recommend a vag-com or at least a OBDII reader. throwing money at it and hoping it fixes it can get expensive quickly.

I lived in Colorado many years and it would get that cold once in a while but a bad coil pack can go any time.

[james12lucy]

Hey Bob, I had the same issue the other day as well. It was -25° north of Toronto and I was having the same misfire. I added more fuel and it was fine. Start with the fuel.