Rs4 b9 issue

2.9 V6 24v TFSI - 444 bhp
bakerstreet
Neutral
Posts: 16
Joined: Sat Jun 23, 2018 7:53 pm

Re: Rs4 b9 issue

Post by bakerstreet » Mon Jul 16, 2018 4:53 pm

I experienced on the motorway today in moderate traffic at a constant 50-55 the HUD gear display dropping the number of the gear until I re-engaged the throttle, so for example the HUD was showing "D6" then it just went to "D".

I looked down at the rev counter and the revs dropped to idle speed of c.750rpm coasting along until i pressed the throttle, "D6" reappears and the engine revs go back to say 1800-2000 or whatever was normal for the gear and speed. I would have never noticed it if i didnt have the HUD in the sport setting (mph, gear, oi temp and lap time).

Is this a fuel saving measure?

thanks
2018 RS4 - Daytona Pearl; Silver interior; 19's;
2014 GTR Black Edition (sold)
2011 M3 V8 (stolen - out in the wild somewhere!)
2004 Carerra 4S 996 (sold - absolute money pit)

Markp
5th Gear
Posts: 1117
Joined: Sun Sep 13, 2015 10:47 pm

Re: Rs4 b9 issue

Post by Markp » Mon Jul 16, 2018 10:02 pm

bakerstreet wrote:
Mon Jul 16, 2018 4:53 pm
I experienced on the motorway today in moderate traffic at a constant 50-55 the HUD gear display dropping the number of the gear until I re-engaged the throttle, so for example the HUD was showing "D6" then it just went to "D".

I looked down at the rev counter and the revs dropped to idle speed of c.750rpm coasting along until i pressed the throttle, "D6" reappears and the engine revs go back to say 1800-2000 or whatever was normal for the gear and speed. I would have never noticed it if i didnt have the HUD in the sport setting (mph, gear, oi temp and lap time).

Is this a fuel saving measure?

thanks
Yes

MikeBent
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Posts: 13
Joined: Sun Mar 25, 2007 1:37 pm
Location: Bolton

Re: Rs4 b9 issue

Post by MikeBent » Wed Jul 18, 2018 10:30 pm

Smara,

Depending on how subtle the effect of loosing speed is, it may (and I’m grasping at straws) be the engine shifting vlalve lift modes. At certain loads and rev’s, the engine switches between reduced and high valve lifts for efficiency.
I’ve experimented and tried to ‘feel’ this when driving and I’ve convined myself that I can detect it, but I may be completely wrong.
If you are not using cruise control and you have a constant light throttle with your foot and the engine load changes slightly when traveling up or down hill, you could have a very subtle effect when the engine changes valve lift mode.

Of course I may be full of s**t....

Failing that, dealers and read the codes etc.

Interested to know how you get on.

Mike
Imola Yellow B9 RS4
Kingfisher Blue C6 RS6
Jasper Green B5 S4 Avant. Milltek & MRC Custom Map

Smara
Neutral
Posts: 13
Joined: Sat Jun 30, 2018 10:08 am

Re: Rs4 b9 issue

Post by Smara » Sat Jul 21, 2018 11:02 am

Hi Mike,

Thank you for your view. The problem happens on perfectly flat roads (no up or down hill) and on different engine revs. So I’m not sure that might be the case. I brought the car to the dealer for a quick check on the ecu and they found no error codes. I will have to bring it back after summer. They told me on a group of chassis interval the had to update the ecu software for a idle problem. But mine was out of the interval. Will keep you posted.

Best

Andrew

PieterZ
3rd Gear
Posts: 305
Joined: Wed May 30, 2018 1:08 am

Re: Rs4 b9 issue

Post by PieterZ » Sat Jul 21, 2018 10:36 pm

Off topic but interesting: what exactly was the idling problem?
All black B9 RS4

Smara
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Posts: 13
Joined: Sat Jun 30, 2018 10:08 am

Re: Rs4 b9 issue

Post by Smara » Sun Jul 22, 2018 2:56 pm

I don’t know exactly. But my guess is a fluctuating idle.

Btw is your idle at around 1000 rpm in dynamic? (Sport mode)

PieterZ
3rd Gear
Posts: 305
Joined: Wed May 30, 2018 1:08 am

Re: Rs4 b9 issue

Post by PieterZ » Sun Jul 22, 2018 7:36 pm

Good question I'll take a look tomorrow.
I do know on a cold start it idles a bit higher and then drops to around 750 after about 15 - 20 sec.
Not sure what it does in dynamic.
All black B9 RS4

PieterZ
3rd Gear
Posts: 305
Joined: Wed May 30, 2018 1:08 am

Re: Rs4 b9 issue

Post by PieterZ » Mon Jul 23, 2018 7:30 pm

You are right.
If the gearbox is in S it idles at 1k rpm, in D it does 750.
It doesn't matter if it's in auto, individual or dynamic.
All black B9 RS4

Smara
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Posts: 13
Joined: Sat Jun 30, 2018 10:08 am

Re: Rs4 b9 issue

Post by Smara » Tue Jul 24, 2018 8:06 pm

ok thanks. Same here.

One update: i discovered that the issue happens only in D and not in S independently from the drive select mode

PieterZ
3rd Gear
Posts: 305
Joined: Wed May 30, 2018 1:08 am

Re: Rs4 b9 issue

Post by PieterZ » Tue Jul 24, 2018 10:08 pm

I'll pay some extra attention tomorrow, but I don't think mine drops ever so slightly when driving along.
Never noticed anything.
All black B9 RS4

PieterZ
3rd Gear
Posts: 305
Joined: Wed May 30, 2018 1:08 am

Re: Rs4 b9 issue

Post by PieterZ » Wed Jul 25, 2018 11:30 am

I just drove on the highway, and the only movement in power or fuel gauges are caused by running up- or downhill.
I had it on acc at around 140 kmh.
All black B9 RS4

Smara
Neutral
Posts: 13
Joined: Sat Jun 30, 2018 10:08 am

Re: Rs4 b9 issue

Post by Smara » Wed Jul 25, 2018 11:49 am

Ok thank you Pieter,

Will keep you posted.

PieterZ
3rd Gear
Posts: 305
Joined: Wed May 30, 2018 1:08 am

Re: Rs4 b9 issue

Post by PieterZ » Wed Jul 25, 2018 12:24 pm

I hope it gets solved! Maybe a bad connection or a faulty sensor somewhere.
All black B9 RS4

parkerrs
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Posts: 4
Joined: Tue Sep 18, 2018 10:07 am

Re: Rs4 b9 issue

Post by parkerrs » Tue Sep 18, 2018 10:16 am

Hi, I have experienced the exact same issue.
Audi dealer looked at me blank when describing the problem.
Have you spoken to your dealer ?

Smara
Neutral
Posts: 13
Joined: Sat Jun 30, 2018 10:08 am

Re: Rs4 b9 issue

Post by Smara » Tue Sep 18, 2018 10:25 pm

Not yet sorry I had to cancel the appointment due to work reasons. I’m going to book another appointment.

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