Woo Woo Woo Woo Woo - B7 S4 Surging Idle on cold startup

B6/7 S4/RS4
#1

I see this thread popping up on Audi boards every fall when temps drop, and noob B7 owners experience the woo woo woo with the arrival of cold temperatures.

This is normal.

This only happens on cold starts. This only happens when the car is in neutral/drivetrain is not engaged. It lasts 10-30 seconds, then idle settles to normal S4 levels (800 rpm). You can just drive the car, (remember engaging the drivetrain stops woo woo woo)…you don’t have to wait for it. My 2007 S4 used to do this. Service at Audi were stumped…till I met a really smart Audi service tech. He explained it.

This is something the car does to heat the cats up quicker to reduce cold start emissions.

It is not the throttle body. Lots of people think that.

If you get tuned, it won’t change it.

If you get piggies, or go catless, it will make it last longer, because your car is struggling to heat up the cats (which aren’t there).

Other audis do this as well, just in other ways. The B8 A4 2.0T uses the turbo to heat things up quicker and it makes this crazy whooshing noise for 30 seconds and is really embarassing. It’s way worse than woo woo in neutral. Go to a dealer on a cold winter morning and ask to start up a B8 A4 2.0T. It is really funny, and you’ll love your woo woo woo when you see how bad woosh is.

Again…this is normal.

Here’s a video of woo woo woo:

http://www.youtube.com/watch?v=u0pZDqTDy3c

If you see people posting about this, please link the countless ‘OMG MY CAR IS GOING TO EXPLODE’ threads on AZ and elsewhere to this thread here on Audirevolution. Will help calm some fears and will show people where to go for good info.

#2

did he go into more detail? Maybe its just feuling up momentarily to dump fuel on the cats for the SAI system to oxidize and heat them up. The car may rev a bit each time it pulses, giving the wooo wooo (whistle tips). Someone with the issue should log afrs and injector duty while this is happening.

my B6 also did the same thing

#3

he didn’t because frankly he could tell I wouldn’t have understood much more. :slight_smile:

you should seriously hear the B8…it’s NUTS. I should make a video but I’m not sure it will capture the sound. Our neighbour’s gardener waved me down in the B8 one morning. He thought something was going horribly wrong with the car lol

#4

What doesn’t make sense to me is why do B7’s do it? I could see Audi changing the tune to make for better emissions, but then all cars with the JHM tune would do it since the tune incorporates the updates.

My 05 B6 never does and never has done the woo woo woo.

Saki I know what you’re talking about on the B8. My dad’s car does the same thing

#5

You should see the revs jump during a cold start on the s/c cars. The second that throttle body opens the blower is rushing air in and the jumps are a lot more prevalent.

#6

The WOO WHOO IS NORMAL AND IT IS A GOOD THING

This actually a very agressive system set up for cold starts. The B6 cars don’t do it as much but they will still do it.

The B7 cars run the SAI pump and thus want to see a cleaner exhaust. From what I know the ECU was updated to run this what we Audi tech’s call a hard iddle. This helps with not just cold start for emmisions but it also runs the oil pump just a little harder on start up. You will notice that not as many B7 S4’s have chain rattle. while they still do its not as much. This was explained to us that the WOO is the SAI and the up rev of the motor is in relation to that and to the cold start oil feed function for pumping cold thick oil to the much needed parts.

#7

I have been posting the past few days on AZ my problem with surging. What has been said in this post makes sense. My car is a B7 (2007) and it did it during the summer, but only on cold startups and for maybe 10 to 15 seconds. Recently I gutted my pre-cats and then shortly after (last week) I installed my JHM tuned ECU, and it has gotten worse to where it will do it for a minute or so. Listening to it from under the hood it seems almost violent, and you can hear the butterfly valve in the TB clicking in unison with the surge.

Everything in here makes sense, and if it legitimately helps with oil pressure and what not then I want it to stay there, but if it’s negligible and is more for heating up the cats (which aren’t there) then I would rather find a way to disable it just for comforts sake.(SAI)

Overall this post was very comforting though, you just have to realize that after reading AZ for months now and only having the care since June I get worried when it does things I am not used to. (noob I guess)

#8

Hmm… My 04 does it. Never saw it as an issue.

#9

did you get a new engine?

#10

see, it took me like 2 years to find the answer with Audi techs locally…and on AudiRevolution, it took less than one day.
Great input Carlos. We forum users are lucky to have you on board!

Welcome to the forum Nico…glad to see you got some insight to the issue’s true causes. Personally I wouldn’t let the car sit and idle in the morning. Just get in and go and keep the revs real safe under 3-4k while everything warms up.

#11

Nope, still the original engine. My Touareg does it as well, just not as much or as long as the S4.

#12

Interesting. What year/engine Touareg?

#13

you should be able to avoid this all together if you just start the car let it run for no more then 10 seconds before you start driving. If you read in the owners manual it will tell you to NOT Let you car sit and warm up this is very bad for the car. The start up idle control/warm cycle will run untill it has met all the requirements. The motor getting upto proper working temp is one of the requirements.

Contrary to old times when you would do well to let your car sit and warm up. This is no longer the case. There is no need to beat on the car till its upto working temps but there is more damage done by letting it sit and warm up from a idle.

#14

Just bringing this up to the top. I was told when I first got my car to always let the revs drop to 800 before driving it, so I would usually let the car idle for a good minute or so. And I would always have an intermittent CEL almost weekly for random misfires, which would pop up shortly after I started driving the car. I could not for the life of me track it down.

As soon as I saw this post I started just turning the car on and driving away. Haven’t seen a CEL, scanned for codes and nothing! Since I normally would have seen a CEL at least twice by now, I’m assuming this was my fix ;D

#15

could be but who knows. Hopefully.

#16

Chances are it did fix the issue. Cold starts are the moat dangerous time for a motor. Your Audi guide even says don’t let your car sit for more then 3seconds before you drive the car. The count is spot on as usual.

Cold start missfires are normal depending on you plugs heat range

#17

I fully appreciate that we should start and not sit idling for many minutes. But what about us in snowy/icey climes? Often I get frozen fluid on the inside of the car and I need some heat to help get rid of it. Any advice? The manual just says to make sure visibility is satisfactory before moving off. That can be several minutes for me.

#18

Good question. Weather is pretty cold here too, I’ve often had to sit for a couple minutes warming up.

#19

Throw the wifes car out of the garage and park yours in there! ;D

#20

Since you seem to have this car thing ;D, why not use your wife’s car as
a) it will be warmer as it’s already in the garage and
b) will stop you getting frozen fluid on the inside of your car!! :smiley: :smiley: