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Recently had an engine management light come on, Audi took a look and found a split in the vacuum system piping, this has now been sorted and the dash light has gone out but the kick at 5.5k revs has definitely gone, any ideas what I should do next?

It also seems to be slightly revving when the clutch is down and slowing down, briefly sitting at 1100 revs before settling down when stationery

I would take it straight back, sounds like they have fixed one vacuum leak and created another.

Agreed - the kick isn't a 100% reliable method however a vac leak could cause minor idle issues as the engine is drawing air from another source other than the throttle butterfly.
So the engine sets the throttle to what it things is a suitable idle but the extra air makes this slightly high until the engine settles and the ECU can adjust accurately.

+ 1, definitely a vacuum leak, the most recent one I had was caused by a failed oil filler cap but as we all know there are plenty of places a leak can occur.....

I knew someone who had this issue and Audi told him that the actuators in the exhaust manifold had stopped working / failed and had to be replaced or fixed.
Might be something for you to query with Audi if its not a vacuum leak.

Mine used to loose its kick on certain days over a month period...then all of a sudden it was back for 18 months until i sold the car..Strange???

Engine management came on again on my way home from work, booked into to Audi York again

I need to learn more about this 'kick'.

Had the car for over a month now, when it went back in and had the new clutch, i honestly thought the car had lost some power, Audi tried and tested the car again and said everything was fine. Still haven't had too much of an opportunity to give the car a real serious blast, although the trip to LeMans this year will see the car being used as it should.

I haven't experienced the 'kick' you've all mentioned, is is that obvious at 5500? my driving so far has just seen gear changes done just before red line and it seems bloody quick, but all the same, this kick, noticeable?

Cheers
M

klauster wrote:It also seems to be slightly revving when the clutch is down and slowing down, briefly sitting at 1100 revs before settling down when stationery

is the cruise control working?
if not, clutch switch

mac911rs4 wrote:I haven't experienced the 'kick' you've all mentioned, is is that obvious at 5500? my driving so far has just seen gear changes done just before red line and it seems bloody quick, but all the same, this kick, noticeable?

Definitely! it feels similar to a turbocharger coming on boost, but obviously much higher up the rev range than a turbo. Try a run with your foot down in 2nd / 3rd from 3,000rpm and hopefully you'll feel it - the first time I experienced it properly in mine on some back road twisties, some rude words came out of my mouth!

mac911rs4 wrote:I need to learn more about this 'kick'.

Had the car for over a month now, when it went back in and had the new clutch, i honestly thought the car had lost some power, Audi tried and tested the car again and said everything was fine. Still haven't had too much of an opportunity to give the car a real serious blast, although the trip to LeMans this year will see the car being used as it should.

I haven't experienced the 'kick' you've all mentioned, is is that obvious at 5500? my driving so far has just seen gear changes done just before red line and it seems bloody quick, but all the same, this kick, noticeable?

Cheers
M

really not a 'kick' as much as a small increase in the rate of the torque/thrust
when you look at the dyno curves you see a little torque hump at ~5000-6000 rpm, it's pretty much flat til then, then a slight increase, perhaps 5% max
but the HP curve is pretty smooth, consistent
iirc it's the intake flaps changing position

look at the graph tab http://www.rri.se/popup/performancegrap ... artsID=281
little bump 5 to 6k rpm, but HP is even slope, no real sharp increase in power
I would not equate it to a surge of turbo boost

I'd like to see accel g graphed in 3rd gear from say 3k to 8k in 0.1 sec increments, see what the difference is at say 4k, 5k, 6k and 7k...I'm betting not much

Many thanks, i'll give it a run later tonight and see what i get from it, experienced 'turbo rush' before from a past 911, power from the RS just seems as is, natural power, need to plan tonights routes now for a few blasts, make sure all's working correctly
thanks again.

mac911rs4 wrote:Many thanks, i'll give it a run later tonight and see what i get from it, experienced 'turbo rush' before from a past 911, power from the RS just seems as is, natural power, need to plan tonights routes now for a few blasts, make sure all's working correctly
thanks again.

I've driven many cars in the last 30+ years and the RS4 engine is one of, if not, the best
as good as any M3 engine

ArthurPE wrote: I'd like to see accel g graphed in 3rd gear from say 3k to 8k in 0.1 sec increments, see what the difference is at say 4k, 5k, 6k and 7k...I'm betting not much

I can do that for you using my pbox. If you just go download the performance box software from racelogic's webpage, you will be able to play with the file and can move the cursor to see the data all the way along (and the data includes dozens of things...speed, time, elevation, long. G, lat G, etc..

I can also just post a chart for you in image format...but I thought you'd like to have the data at your hands.

ArthurPE wrote: really not a 'kick' as much as a small increase in the rate of the torque/thrust
when you look at the dyno curves you see a little torque hump at ~5000-6000 rpm, it's pretty much flat til then, then a slight increase, perhaps 5% max
but the HP curve is pretty smooth, consistent
iirc it's the intake flaps changing position

I think it's a few things...intake adjustment, cam profile and of course the airbox flap opening...as well as (most important I'd bet) the torque limiter in the stock ECU file being lifted at 5200 RPM or so. You can see that in my log below...throttle is heavily restricted in gears 1, 2, 3 (52%) up until the 5000-8000 range: