RS246.com Forum :: The World's #1 Audi R, S and RS Enthusiast Community

I have had my RS4 for about 3 weeks now, after being a very happy RS2 owner. Last weekend I went out for a burn and was quite dissapointed.
I brake with my left foot through corners to scrub off speed and to keep the turbo spooling, when I did it in the RS4 power dropped off completely. I would then have to release brake and wait about 3 to 5 seconds for power to pick up again.
Almost as if electronics cuts fuel supply when brake is activated. Tried it with traction control off, no difference.

Could any of you please see if your cars do the same. Can be tested in straight line as well, with medium amount of throttle and medium braking.

Many thanks.

This is a well documented 'feature' of the S4 & RS4 with it's electronic throttle - you might think you've got your foot to the floor, but the ECU knows better than you and is reducing the throttle input to the ECU electronically

You will also find that it won't let you have 100% throttle until after 3000rpm in the RS4 - this can be removed by a decent tuner, but I'm not sure about the left foot braking problem you have - maybe toe n heel with your right foot

My old S4 used to do this, but my B5 RS4 didn't This function may get removed when you do a re-map (much like the speed limiter??)

I have just noticed though, that the B7 also does this - probably something to do with not overheating the brakes.

In any case, I think it's normal.

Throttle cut on braking an also be removed by a tuner I think.

It's either part of MRCs standard remap or my '98 S4 doesn't have the feature, think it's due to the remap though.

It's either part of MRCs standard remap or my '98 S4 doesn't have the feature, think it's due to the remap though.

All S4's have electronic throttles - it's defo the MRC remap, and I think they're they only ones who remove this 'feature'!

Mihnea gave me the choice when I got remapped at MRC. Obviously I chose to enable left foot braking.

My 98 B5 S4 does the same, and it wasn't disabled by the collins remap.

You can do it if you press the brake then the throttle I think ? Defeats the object of LFB I know but a designed in feature for sure.

I thought all tuners disabled it in there maps, but apparently not. There was a thread about it a while back. MRC do/can for sure.

I thought all tuners disabled it in there maps, but apparently not. There was a thread about it a while back. MRC do/can for sure.

No, I had a look at some logs from Gordons RS4 MTM map a few months ago and his throttle was being 'massaged' by the ECU - he wasn't allowed full throttle below 3krpm (some might say it serves him right!)

Is this not the ESP kicking-in?

There was a piece about this in Audi Driver a short while back, I'll try and find it later . . .

It could be ESP controlling it, but it deffo is the ecu overriding throttle inputs when brakes are applied, it will allow you to blip throttle on down shift but not left foot brake in standard map form.

Thanks for the great response. Seems like I will have to have it removed via re-map.
I did try it with ESP off, but still does the same.

The ESP has nothing to do with the fact that you don't get 100% throttle until 3k RPM on an RS4, it's only because of how the stock ECU is mapped.

Its a safety feature to increase brake and engine life! My APR chipped S3 still has this as I found out on Sunday when I tried to left dap the brakes after driving through a flooded road

Dave