Car doesnt like to downshift after resetting battery

[ElliotA6]

Hey guys,I have a 2007 Audi A6 and I recently put subwoofer in about 3 days ago. They had to reset the battery. Since then, the car likes to stay in high gear and stay there until you floor it, then it acts perfectly normal until you turn the car off again. What causes this?
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[95blkmax]

These cars are very sensitive to voltage fluctuations. What is the amp grounded to? is it bare metal or a painted surface? Also, depending on how strong of an amp you're running (and how high you have the gains set to), when the bass hits you could be having some serious voltage drain for that momentary boom. How old is your battery? If the system is big enough, maybe running a capacitor in line between the battery and the amp would be a good idea.

I run a 10" Pioneer with a 2-channel Jensen bridged (I do not recall how strong), but I wasn't going for any big boomy bass, just more low fill that the Bose can't hit. With a fresh strong 850CCA H9 battery, and no capacitor I have no issues (3yrs with it now). I do have the amp grounded at the battery hold down bracket between the bracket and the bolt so it's a bare-metal ground point.

[ElliotA6]

These cars are very sensitive to voltage fluctuations. What is the amp grounded to? is it bare metal or a painted surface? Also, depending on how strong of an amp you're running (and how high you have the gains set to), when the bass hits you could be having some serious voltage drain for that momentary boom. How old is your battery? If the system is big enough, maybe running a capacitor in line between the battery and the amp would be a good idea.

I run a 10" Pioneer with a 2-channel Jensen bridged (I do not recall how strong), but I wasn't going for any big boomy bass, just more low fill that the Bose can't hit. With a fresh strong 850CCA H9 battery, and no capacitor I have no issues (3yrs with it now). I do have the amp grounded at the battery hold down bracket between the bracket and the bolt so it's a bare-metal ground point.

How come this only happens before I press the kickdown button under the gas? After u do, everything is normal.

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[95blkmax]

Have you checked for codes to see if the computer is recognizing something funky in its systems? You may need access to a VAGCOM as OBD2 codes pertain mostly to the powertrain. It is certainly odd.

So you never had any transmission issue prior to the sub/amp install? BTW, there's no kickdown button on these cars. Tranny up/downshifts by the TCM based on a table of accel pedal position % Vs engine RPM & vehicle speed.

Here is a scenario- If you had presented the same scenario as you did, with the removal of any mention of it happening after an audio system install... I would be brainstorming for causes of a slipping transmission (be it mechanically or electronically-caused). I would be leaning more to electronically-caused since you said that once it finally does a downshift under WOT, everything goes back to normal operation until you shut off and re-start again. The sub/amp install and this deal could just be pure coincidence.

Good luck!