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Is my S4 broken? reason for asking is I couldn't shake a 2.0T A4 on the dual carriageway through Basingstoke

Either it was a seriously modified car or mines not happy, any suggestions as to how to check its ok apart from letting Bexley Audi test drive it

Thanks

Pete

Plugs, intake manifold (bolts tend to unscrew), Vag-Com checks.

That the only things i can think of for the time being

MAF faulty?

I have a B6 S4 Cab (2005) and have had exactly the same problem. Sometimes the performance would be mind blowing, but most of the time just so, so.
My car was origionally owned by a woman, so knowing how my wife drives the S4 ( short shifting) led me to believe that the engine adaption had cast a bad spell.
After researching the Bosch engine management system I found a little "easter egg" gem.
If you press the brake pedal ( not hard - just so the ECU knows you have pressed it) and, then immediately slip your foot off the brake and on to the throttle (full throttle) the ECU thinks you are left foot braking and switches into a racier mode. I think it must just ignore any adaption until you switch the ignition off.

Use a high gear and spend, maybe half a second touching the brake and a fraction of a second full throttle. Do it twice - just to make sure. Even the exhaust note changes. Oh, and make sure that you are using something higher than 95 RON fuel - it makes a big difference.

Regards, Chris.

Oh, one more thing:

I have used the vag-com software quite a bit and every thing seemed fine. I have done logged runs, watching many parameters. The only problem noticed was that the throttle would only register 95.7% open at full, so I performed a throttle body re-alignment with the vag-com and it now registers 100%. However, the only thing that seems to switch it from a fast car into a super car is the left foot braking trick.

Please give it a try and let me know how you get on.

I have just used the vag-com to reset the engine adaption, so we'll see what happens.

Regards, Chris.

Good tip, might have to give this a go later.

Hi Chris,

Tried your suggestion and it feels like the power is coming in at a lower rpm so reasonably sure something is changing. I will check it again just to make sure I believe what my backside is telling me.

I'm not sure if it feels any faster as you kinda get used to its performance and only really see it when compared with something else. I suspect that the perpetrator of my concern was in a modded car, suspension too stiff for his fillings as he was bouncing around a bit and seemed lower than usual even for an S-line (apologies for swearing).

Any suggestions as to how I can disable to its learning mode, just want it dumb and doing what its supposed to..

Thanks

Pete

Hi Pete,

The way the Bosch ECU works is that you supply a "torque request" from the throttle pedal and the ECU decides where to put the throttle butterfly valve and all the other things such as injector time, etc. It basically decides what "charge" to put in the cylinders. I learnt that the Bosch Metronic system has this left foot braking thing where the ECU will honour your torque request via the throttle after you do it.
Has your battery been out at all or discharged? Has it been in the dealers for a service? The throttle body must be re-aligned if the battery has been disconnected - I think they normally disconnect the battery for a service. The Audi service guys don't even know what a TBA is
Anyway, my throttle body was out of alignment and didn't register 100%. My mates S8 4.2 was only opening to 87% and we calculated on a logged run that he only developed about 180 horse power ( calculated by the formula 80% of peak mass air flow - which was 220g/s)

The only way you can reset the Throttle Body Alignment is with something like the Vag-Com software. In total this cost me £30 for a cable and it works fine.
Also, the engine adaption ( learnt driving experience) can only be reset with the vag-com.
As a matter of interest since I reset the adaption and the TBA, it's a different car.
My mate has just "Revo"ed his Passat 2.0TDI and it's a lot faster now but could never touch the S4 - it's only got 4 cylinders

I would guess that your throttle body needs aligning. If you are anywhere near Newcastle you're more than welcome to pop in and have a go with the Vag-Com.

Regards, Chris.

Hi Chris,

Only had the car for 6 months but always felt it was not as good as the B6 S4 (less smiles per mile). No doubt the battery has been disconnected and this could be the solution. When I next feel like gambling at the dealer I will request them to check the Throttle Body alignment and kill the engine adaption (if possible). Why they make things this complex I have no idea, particularly as mostly they cannot fix it themselves anyway.

Getting to Newcastle, it is probably cheaper to send the car to the dealer to fix as based in Wiltshire but thanks for the offer.

Regards

Pete

Pete, I'm not a million miles away from you your thread has me seriously intrigued. I wonder if there's anyone in the not very south or south west with a VAGcom who would be happy to meet and plug in? Be happy to donate to the cause myself.

The other thought is Dialynx on the west side of Swindon. http://www.dialynx.co.uk/ Whislt they specialise in blown cars, I more than trust them to read the ECU.

Hi,

I had thought of Dialynx in West Swindon, friend had his S3 sorted out there and was very pleased. I not over keen on plugging in and poking about myself just in case I mess something up (might think it's an A4). I work on equipment that is software upgradeable and always seem to mess it up when poking about.

Will give Dialynx a call though.

Cheers

Pete

nihc wrote:The only way you can reset the Throttle Body Alignment is with something like the Vag-Com software. In total this cost me £30 for a cable and it works fine.

How did you get VAG-COM software and a cable for £30?

ebay special probably...

I fitted a new battery a few months ago, so guess I need the TB reset. On Alfa GTA's this can be done with an ignition sequence over timed intervals, so wonder if the same can be done with the S4 too.

Might give it a try,

Unlock car, turn key to 'ignition' (2nd position) for 90 seconds, (should hear the TB making all sorts of whirring noises). Back to position 1 for 90 seconds, then start the car.

Maybe someone with VAGcom and a miss-aligned TB could see if this works?


Oh, I tried the left foot braking trick, and it certainly works. Makes the throttle much sharper like when the car is in 'Sport' mode. (mines a Tip/Auto)

Hi,

Unfortunately, the only way to reset the TB is with something like a vag-com.
You will hear a click with the "door open" proceedure, but it's only the TB returning to rest since you haven't started the engine.

Regards, Chris.