2009 A4 Avant surging uphill

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Oct 12, 2009 | 03:40 PM

Robsibis

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2009 A4 Avant surging uphill

My 2009 A4 Avant does a "surge" on again and off again uphill on the local bridge. The incline is probably 8% and about 1 mile in length. The surging is subtle but noticeable. The tach fluctuates up and down. If I accelerate it will go away. It usually happens only when going a constant speed uphill. Looks like this has been described in other forums as transmission hunting. Has anyone else experienced this? Solutions?

Robby Bennett

Oct 12, 2009 | 08:53 PM

UmIsThisThingOn

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From: Raleigh, NC

I've experienced this in multiple cars when going up a grade like you describe.
Sometimes when I'm using cruise control, sometimes when not.

I took it to mean it was normal.

Oct 13, 2009 | 03:29 AM

Art234

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From: Long Island, NY

I noticed this yesterday driving home from Washington DC to New York. It happens only on moderate acceleration, usually in 4th or 5th gear, let's say from 40-70 mph. If it upshifts to 6th it stops, but there is a 500RPM swing of the tach, and you feel the car surging. I am about to have the 5K service, and will ask them to look at this.

It does NOT shift gears during this time, however, it just seems to be surging--someone said it might be changes in the turbo boosting, but I am not sure.

Mine is a 2010 A4 2.0t Quattro by the way.

Oct 13, 2009 | 09:11 AM

ScottAW

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The 500 rpm drop used to be the overdrive on an automatic transmission. I've noticed this as well, where the RPM's will shift even though the gear is still in D6. Used to be this was for fuel economy, and is nothing more than the torque converter locking up in a certain manner to allow this to happen.

When going up a grade like that I would slip the transmission over to manual mode to eliminate any hunting of gears.

Oct 13, 2009 | 09:37 AM

av_audi

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If you are really sure the car is not downshifting, it is just the torque converter unlocking under the increased load and letting the transmission slip (increases RPMs).

As suggested, just downshift to a lower gear.

Oct 13, 2009 | 10:22 AM

SFV A4

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Quote:

Originally Posted by Robsibis

Sounds like the grade logic feature. Your transmission should be sensing when you are on a hill and hold gears longer. Sometimes it feels strange, although I don't think it's supposed to jump up and down fast. The process is gradual and smooth. Just a guess.

Oct 13, 2009 | 10:33 AM

Shobaffum

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Mine does this too - RPMs surge but it doesn't change gears. It doesn't necessarily have to be a hill though. It happens when accelerating slightly on the freeway.