Cars older than 100k....

[tartan_rob]

Guys - does anyone have an S4 with more than 100k on it? Mine has about 107k and still going strong without any major failures (touch wood....). But I do a lot of motorway miles, in fact all motorway miles (about 110 a day). Does anyone else have experience of similiar relatively trouble free motorway driving..?

On reading some of the posts here, you guys are talking about changing turbo's anyhting between 50 and 100k miles. Is it just that I have not tuned nor that I do not drive it hard all the time (and change the oil for race spec fully synthetic every 4k miles) that has spared my car from the big car repair man in the sky...?

[S2tuner]

IMHO the turbos problem is related to 2 issues which are usually seen as fatalities, when IMHO they aren't:

1: heatshield on the driver's (UK) side turbo: the wastegate actuator rod actually rubs against the heatshield and the wastegate doesn't open enough when it has to, so the driver's side turbo actually works more than the other one. This is what causes 80% of turbo failures on S4s. The problem is known by Audi AG but they don't want to make a recall as it would be too expensive. 5 different german tuners whom I'm working with/for confirmed this to me already, and they have confirmed to me talking with Audi AG about this, so Audi AG is aware of the problem.

2: too violent chips. High boost at high revs on the 2.7T brings lots of power, at the expense of the turbos, especially if the heatshield issue is not addressed. Some tuners do make their chips with just too much boost at the top end, to get ultimate power out of the car. Example: Giac X chip that claims 80HP above stock (that makes it 330 to 345 HP) running 1 bar at the redline, or Abt 320HP chip that runs 0.95 Bar at 7000 RPM. This is just too much boost for the tiny K03s, and it's actually not even inside the compressor map anymore if you know how to read a turbocharger's compressor map.

IMHO, I've seldom heard of turbo failures on MTM chips, nor have the cars I have tuned ever had a turbo problem. Being conservative and knowing what's efficient and what's not can really save the turbos on these cars. 95% of all Swiss S4 owners that are running Abt chips (because Abt is an official tuner in Switzerland so they keep their factory warranty) have had their turbos replaced at least 2 or 3 times. IMHO it's totally unacceptable...


So, IMHO, I wouldn't consider turbo failures as a fatality on these cars. It's only down to how much power you're making on them....

HTH,

Mihnea

[gavsteryoung]

I think the key here is not having your car chipped. My car has 80k on it and is standard... orginal turbos and they still pull well, stay quiet and got a good bill of health from Kim Collins!

If the car has been sitting for 3 or 4 days then I get the very slightest puff of blue smoke when starting, but I gather that is normal for this kind of milege as the oil seals in the turbo do wear a little!

Personally I wont get my car chipped even though I would love to see what they go like. I dont want the 4k repair bill for new turbos.

I would rather save the money for a later S4 with low low miles and chip that or even the V8 S4 (but I would miss the turbos, but engine noise would maybe go someway to make up for it!)

[gavsteryoung]

Mihnea

So in theory would it be possible to create a custom map that just gave about 295bhp for instance.... and would this be done by just different boost levels?

I guess im also wondering if any power increases can be made from just altering the fueling or some other parameter and not the boost. And hopefully not stressing those turbos too much!

[tartan_rob]

Thanks guys. In essence the point is either to be very careful who tunes the car or not to have it done at all and to get the off side heatshield checked to make sure it ain't touching wastgate actuators.....UNLESS you have money to burn (either in tuning and changing lots eg K04 turbos or in repair bills)....

Unfortunately my beast is a work horse so I think I'll continue to change oil & plugs frequently and leave her std. With some luck the std car and components will see out my time with her without too much hassle....on that note, does anyone else have noisey wishbones (either upper or lower) on the front of the car? I have replaced all passenger side ones approx 1.5 years ago and I'm sure they've gone again. Drivers side are starting to knock too....perhaps its just because I do lots of miles....or perhaps the S4 eats wishbones like a Fiat Uno Turbo eat's front wheel bearings (i.e. every 6 months).

Keep smiling...

[S2tuner]

Yes, everything is possible. Personally, I'm not a fan of "boost is power", and IMHO there's lots much more to be had by running slightly less boost but lots of advance and a leaner mixture at WOT in order to get power. As I said earlier on these forums, it's all down to the tuner's philosophy and how each one perceives tuning. Lots of people just turn the boost up and adjust the fuel sort of accordingly in order to get the power, to me this approach is just too simplistic. IMHO, 295-300HP and 480-490Nm shouldn't put any stress on the turbos in the long run provided the heatshield issue is taken care of (it requires a little bending in order to clear the WG actuator rod) and power delivery should also be much "crispier" because of running high advance/low boost/leaner mixtures. By leaner mixtures, I don't mean too lean mixtures, but generally speaking, as you up the boost past the efficiency limits of a given turbo/hot side/compression ratio combination, timing gets retarded because of pinging and you have to dump loads of fuel in there to keep the combustion temps and EGTs within reasonable limits. This generally translates into an engine running about 10.5 to 11:1 AFR at WOT, which is plain silly IMHO. In some cases, lowering boost by 0.15-0.2 Bar, adding 5 to 8 more degrees of timing and reducing the fuelling to about 12.5:1 AFR at WOT gives the same performance, better fuel mileage, lower exhaust backpressure, same EGTs and MUCH less strain on the turbos in the long run. Again, to me high performance tuning means respecting the engine and its components, not just being in the quest for the highest power you can get. What's the point in getting 350HP on stock turbos on a bone-stock S4, if it's only for a couple of days before you blow both turbos up? IMHO there's no point. I'd rather just do 295-305 HP but be sure that the customer won't come back to me after 2 years and tell me I'm responsible for blowing his turbos up...

HTH,

Mihnea

[S2tuner]

Rob, it's all up to you and if you don't feel comfortable tuning your car, just don't, period. A turbo bill doesn't only mean money but also being car-less or driving a POS car for at least a couple of days.... that's also something you have to consider if you're driving 110 miles a day, where IMHO you'd be going nutz if you were driving a corsa/nova or taking the train

As for the wishbones, sorry, I can't help, I'm no good on suspension stuff


Cheers,

Mihnea

Thanks guys. In essence the point is either to be very careful who tunes the car or not to have it done at all and to get the off side heatshield checked to make sure it ain't touching wastgate actuators.....UNLESS you have money to burn (either in tuning and changing lots eg K04 turbos or in repair bills)....

Unfortunately my beast is a work horse so I think I'll continue to change oil & plugs frequently and leave her std. With some luck the std car and components will see out my time with her without too much hassle....on that note, does anyone else have noisey wishbones (either upper or lower) on the front of the car? I have replaced all passenger side ones approx 1.5 years ago and I'm sure they've gone again. Drivers side are starting to knock too....perhaps its just because I do lots of miles....or perhaps the S4 eats wishbones like a Fiat Uno Turbo eat's front wheel bearings (i.e. every 6 months).

Keep smiling...

[SimonS4MTM]

So without going outside to look at my car, is it easy to check the WG rod clearance with the heatshield?

[S2tuner]

Simon, I'm not sure how easy it is to do, I have never done the job myself as I've always had my good friend who's a mechanic take care of all mechanical-related and inspection issues so far... I'll ask my friends from germany and let you know when I find out, but IMHO the driver's side turbo should be a b*tch to get to on RHD cars because of RHD related stuff that's not supposed to be there to start with

Cheers,

Mihnea

[Dippy]

Of course I am not going to dispute Mihnea's post, however I will suggest that there are two more reasons for turbo failure, and possibly they are connected.

I have spent a lot of time reading reports from mainly the US about turbo failure. My conclusions are:

1) Audi DID make a design change to the turbos in the area of the oil lines in order to reduce the risk of coking causing insufficient lubrication. There is an AoA technical bulletin about this. Whether or not European cars were affected I do not know. However the point is that in some early S4s the oil lines would have been more prone to blockage than in later S4s.

2) Lack of care and maintenance by the driver/owner.
In the US many dealers were using mineral oils in the S4, and this is more prone to coking than synthetics.
Not allowing a cool-down period for the turbos before turning off the ignition, risking hot-spots and consequent oil coking.
Not allowing a sufficient warm-up period before driving with heavy boost. This risks overstressing the turbos before the oil is doing its job properly.

I think you will find that the MTTF (mean time to failure) for the turbos on an unmodified S4 is indeed less than 100K. Turbo technics suggest 75K is typical. However of course this is purely statistical based on actual failure data. You will not get any accurate figures for the S4, even from Audi. This is because the data sample is small (total number of cars which have had turbo failure), the variables too wide (modding, maintenance cycle, driving style etc, etc), and the accuracy of reporting any of those variables too unreliable.

There is no doubt that my turbos are more likely to fail earlier than yours because my car is tuned. My turbos can make up to 1.35 bar and yours only about 0.8 bar. However there are still all the other factors. Maybe you can go another 100K on the same turbos. But maybe you have a hairline crack in one of the components which is slowly and erratically growing...

What I will suggest is that you have had a good run for your money and shouldn't be surprised if your turbos start to complain that they've had enough and want to retire. It might be worth thinking ahead to what you want to do when they do need changing.

http://www.turbodynamics.co.uk/useful.htm
http://www.turbotechnics.com/turbo/faq.htm

[S2tuner]

Dippy, agreed on the oil lines design and lack of care factors, they are major factor responsible for turbo failures on other cars as well and on basically all turbocharged cars. Mineral oils are bad for turbo engines, and so are fully-synthetic 0W30 oils too.

HTH,

Mihnea

[DuncS3]

Mineral oils are bad for turbo engines, and so are fully-synthetic 0W30 oils too.

HTH,

Mihnea

Hi Minhea,

The recommended oil for the RS4 and S3 is Castrol SLX (503.01) which is 0w30 I believe?

If thats correct, can you clarify why you think its bad for turbo engines?

Dunc

[S2tuner]

Dunc, apologies, I'll get back on this tomorrow, I have to run right now to germany to pick my new S4 2.7T up...

Cheers and thanks for your guys patience,

mihnea

[Pete.S]

Rob

Sounds like you're in the same predicament I was in last year, and your driving characteristics are very similar too (I covered 1000 miles per week in my old B5). When I swapped to the B6, my standard, unmodified B5 had over 140k miles on it, with no turbo problems at all - still pulled as well as when I picked her up on 22k. Only recommendation I'd make if you're going to keep the B5 is that you (if you haven't already done so) change the MAF sensor: relatively cheap, but transformed the car (I was getting flat spots at high speeds), and in agreement with Dippy, always, ALWAYS wait 'til the oil's warmed up before hitting boost (I've learnt that from many years of turbo-powered car ownership).

Only real problem I had with the car was leaking rear diff seals (twice).

[S4driver]

Here comes the kiss of death
Mine now has 111k and rising. The previous owner had an MTM remap done at 107k (i think). No problems so far.

Me, i like to think its pot luck when your turbos go,or as Mik said,if its been tuned its done sensibly ,or not had an abusive owner......My Rs2's turbo got to 165k miles before it needed a new one, whereas some have been changed at far,far less than that.