barrak

Muffler: My 4.2 Q7 developed a low mechanical vibration noise in the muffler @ odo 2500 km (to be replaced by the dealer today). The rythmic mechanical contact noise occurs only when engine is idling, once I drive off it disappears.

TPM: I did report earler on the TPM constantly sounding low tire pressure alarms, especially for the rear tires. It turned out that there is an adjustbale sensitivity setting that determines the acceptable operating range.

Adjustment is via a portable computer equipment (MS Windows operating system). When the dealer checked my vehicle's TPM sensitivity range it was set to 1.9 - 3.8 bar. He reset it to 1.8 - 3.6 bar. That still didn't solve the problem so he promised a re-check during the muffler replacement job. He did claim that 1.8 - 3.6 bar is the minimum setting (maybe he needed to key in the tire size to get a lower setting, I'll ask today). Otherwise, I have to raise the pressure level in the rear tires at least.

Right now I have my tires set at 37 psi all around and the TPM is not happy with that. My tires by the way are the Goodyear Eagle F1 20" 275/40 (or is it 45?). When I first took delivery of my Q7 the pressure was set over 40 psi all around and the TPM was happy. That however made the ride on the 20" wheels unacceptably rough. I guess 37 psi fronts / 40 psi rears is not that bad.

---barrak

Yea Snow

Your tire's optimal performance (if you don't live in an extreme too hot/cold locale) is 35. Try that, then reset monitors via the MMI.

barrak

That was my original aim; 35 psi all around. TPM just wouldn't accept it. Dealer couldn't figure it out either.

Anyway, I just got my Q7 back from the dealer after the muffler job. TPM is not complaining so I checked the tire pressure. Guess what... it was 40 psi all around!

That's it... I'll just keep the rears at 40 psi as they are the ones that constantly trigger the alarm, and reduce the fronts to 35-37 psi.

Your input is appreciate anyway...


---barrak

Yea Snow

My Audi tech friend in Germany says to adjust to desired pressure, drive 5 minutes over 40mph, then go thru the MMI windows and activate the new settings, & repeat. Otherwise there is no way to tweek the chip, so you would need to replace the valve monitors. These are desinged to accept a wide range of pressure levels to accommodate towing, heavy loads, etc. I would put up with the yellow light in the window rather than drive at 40psi