Hey there, new guy here. Thought I'd get right into it with my first question.

2002 A4 3.0 Quattro with tiptronic. Sport package, leather and I think thats about it for options. 48,000 miles on the clock and no other issues that I'm aware of.

When driving the car there is a vibration felt throughout. It only appears to happen under very light throttle applications...like cruising on the highway. Goes away if I floor the gas pedal. I've noticed whenever I pull out of my driveway first thing and the motor is cold it hesitates severely when I hit the gas pedal, this improves when it gets warmer...like I get to the mailbox, stop, see that its clear and step on the gas to pull away, but the only thing moving the car is gravity and the idle...press a bit harder and it surges away...it feels almost like the ESP is inhibiting throttle response, except there's nothing slippery to cause it. If I drive it hard the car is a champ, accelerates like my old SHO but wihtout the cheap Ford surroundings or fwd losing traction at the stoplight.

I was thinking things like fuel filter, plugs, etc, but the feel of it is liek there is a disconnect between the gas pedal and the throttle...it occurs to me that the car is a drive by wire system so its possible that I've either got a bad rev of the software on the computer and maybe a flash to update is all I need to do or maybe I've got a sensor out of whack and its telling the computer its always cold and its running rich or amybe the reverse and its always running super lean?

Its definitely not the tires or anything else...if I'm cruising along and its doing it, if I take my foot off the gas it goes away...its got the be the fuel delivery or somethign the computer is doing slightly wrong.

I'm perplexed but need to get it fixed. If this seems like a software issue to you guys, is there any way to tell what rev I've got and possibly do the flash without going to the dealer...I'd prefer to avoid them if possible since they're not very nice people to deal with and charge a mint since its a fancy brand...but they're also the only Audi place for a 45 mile radius. If I have to I will go there.

Thanks for any suggestions.

 

Scan ecu for codes?
Is the car chipped, or stock?
Does it only do it when its cold, or just worse when its cold?
The coolant temp sensor failing can cause some issues, you may want to try to replace that.

 

I've done no hard diagnostic work as of yet, so I haven't checked for codes...figured no CEL, no codes. Can I just go to Autozone and plug in the standard code scanner or is this an Audi-specific thing?

Its more noticable when cold, but this happens all the time. We took a trip across the state to my brother's house a month ago and the shuddering on the freeway was constant while cruising right up to 75-80 (our max speed on the trip). When passing hard enough to downshift 5 to 4 or accelerating out of the toll booth there is zero vibration, also none when decelerating.

As far as I am aware the car is 100% stock...we bought it in January.

Where is the coolant temp sensor located and is it a testable part or just replace to see if it helps?

 

Coolant temp sensor is cheap enough to replace without testing. I don't know where it is on the 3.0 engine. On the 1.8T it's located on the back end of the block between the engine and firewall (right behind the valve cover).

Your car may havefault codes stored that will not trigger a check engine light. Autozone, Advance or a nice person with VAG-COM will scan your car for codes for free. You can look up the codes on VW Vortex or Audiworld. Vortex seems to have a more comprehensive list of codes and combination of codes.