B5 S4 Tuning Specifics

[SunDiver]

Hi Folks, I've been lurking thus far. I recently bought a 2001X B5 S4 and very nice it is too - just under 50,000 miles. I have a number of questions in respect of modifications geared towards performance and would hugely appreciate answers from those in the know.

As a bit of a background I've done a fair bit of general turbo tuning. I also run a 250hp/230lbft Turbo MX-5. Very very quick, principally because it's so light at only just over a tonne. High speeds are no fun in such a car (too noisy and lacks stability and gears(!)) but acceleration is as quick as most anything. I've owned it from new seven years ago and I fitted a turbo (and about everything else you could do - brakes, suspension, clutch, ECU etc etc etc) four years ago. No problems to date. I've spent considerable time in mapping the car both from on-road datalogs and time on a dyno. I started with base maps and altered them to be more car specific once I got an on-board wideband O2 sensor. These maps were further tuned with the arrival of new additions like cats, altered downpipes, new fuel rails etc etc. In summary I'm pretty familiar with the basics of turbos and tuning - I've read Maximum Boost and Forced Induction Performance Tuning.

BUT... I know nothing about the metrics of S4s yet and little 1.8 four cylinders are some way from bi-turbo 2.7 V6s! To my questions:-

i) Where can I find a plot of ignition advance for the OEM maps and for a typical generic remap? I'm curious to see how things are different for the S4. I'm sure I stumbled upon this once online before I bought the car but can't find it now.

ii) I've spoken to a couple of of UK tuners regarding remaps and was really surprised that most remaps are generic rather than car specific. One tuner even said that the generic remap would even accomodate the addition of a full new exhaust without change. This worries me - in the past I've seen MX5 maps from others running similar (and in some cases the same) setups to me that are not suitable for my car without tweaking, either because they're knock-prone (and trigger the knock sensor) or because the A/F ratios aren't quite right. I know I had to add considerable fuel when moving to a more free-flowing exhaust. Are there any tuners that will do a custom map and provide a wideband A/F plot? I appreciate why they offer generics and understand why but I'm keen to know what's peoples' opinions are? I know you can't compare MX5s to S4s either of course - I'm just keen to see what (if any) tuning knowledge I have can be transferable.

iii) What A/F does the OEM map run at under boost? How much leaner do remaps take it (if at all?).

iv) What's the OEM peak boost and how much does a typical remap raise the boost level?

v) The S4 presumably has a knock sensor (or two)? Where are they situated? Also, does the OEM ECU adjust timing and fuel for intake air temperature or not?

vi) Is there much of a difference between a standard remap and a remap with downpipes, cats and exhaust? - I would expect so but would like to heard opinions from those who have tried both? I don't want to modify this car too much (no turbo/IC/Fuelling replacement to RS4 spec etc) and ideally stop at just a remap or remap with exhaust. I see both AMD and QST sell the metalwork and remaps for these two scenarios. Thoughts?

vii) Is the OEM O2 sensor narrow or wideband? Is it pre or post cat, or both?

viii) S4 brakes are frankly rubbish or is it just my car?

Any answers greatly received. I'm expecting to enjoy this car. I'm more than happy with it to date - much better than I was hoping for. I've never had an Audi before and it's considerably nicer than the M3s I was originally looking for. I'm already near certain I'll move onto another Audi of some description after this one...

Thanks!

[DaveP]

Hi...and welcome to the site!

Firstly, I'm no tuner, but this is how I understand things...

There are very few people (if any) in the UK doing they're own remaps as far as I know...I think it's more common in the States (especially with the S4) - although the methods they use aren't optimal as I understand it (tricking the ECU rather than directly altering the map).

Also, as you stated, I imagine the ECU is way more complex than an MX5...I honestly believe there aren't many people capable of optimally remapping/tuning them...

Regards to the post exhaust map...I agree with you completely - and similarly, there are only a couple of tuners who offer 'custom' mapping.

It might be worth PM'ing Mihnea (username S2tuner)...as I'm sure he'd be able to answer all of the above..he can provide custom mapping and his code is pretty damn good IMHO.

Oh, and yes...the brakes are rubbish!

[JonnyX]

Hi,

The S4 has a bosch motronic ME7.1 ECU. Some details are covered in the study guide which I think you can download from
this site. It's quite difficult to map this ecu yourself as maps are checksummed (if you change the maps you need to
change the checksums). Basically, yopu need some software like: http://www.evc.de/en/product/ols/ which can calculate
the checksums for you. Speakl to Mihnea/s2tuner, he can tell you just how hard it is.

Cheers,

Jon

[alastairg]

Hi
I have just had the RS2 custom mapped by Mihnea. He is one of a select few in europe with motronic knowledge and software access. He will be able to custom map your S4 with all the safety parameters intact. In fact Mihnea runs an S4 himself which he has remapped.
He knows his stuff and managed to put up with my questions for a whole day while he re mapped the car as we travelled to the S2 forum garage meet.
He is setting up in the UK as we speak under the name MRC tuning so I would PM him here 'S2 tuner' or S2 forum 'Mihnea'. There may be a delay in response given the above circumstances but he is the man you should contact.

[kies4]

you can download the s4 engine study guide here http://www.s4-mtm.co.uk/library.htm its got detailed diagrams in pdf format, VAG training doco. Its near the bottom of the page

[KayGee]

iii) Typically 12.5 for OEM and chipped cars.

iv) .8 bar std, 1.1-1.2 bar chipped. This trails off in both instances by @ .3 bar to the red line.

v) Yes two, located on each head (fairly sure they are shown in S4 engine guide). Yes it does. Bigger I/C are your friend.

vii) O2 sensors are narrow band, you have two or four depending on MY. Post 1st cat all MY, post 2nd cat if you have 4.

viii) brakes are rubbish, only when pushed hard, should be good initially but fade alarmingly.

You need to purchase Vag-com and a test lead, it'll allow you to observe everything you'll ever need to know.