Ooopppsss

[Joshie]

Joshie

I'm guessing that yours failed ?

Who do you insure yours through with the mods on ?

Hi Jeff,

Some months ago my KO4's failed after 8000 miles because a certain gearbox company failed to reinstall the gearbox correctly after they repaired it. The result of this was that the gearbox moved and caused the exhaust to move against the turbos causing them to fail.

Audi warranly invalid so I need to take this gearbox company to court to get my money back. [img]images/graemlins/rocketwhore.gif[/img]

[jeffw]

Ahhh...had me worried that there was a inherent problem....sorry to hear about your problems !

[Joshie]

Thanks Jeff.

I can recommend Kleenex BTW, you'll need a big box when you get you S4 back, fully fettled of course. But don't take my word for it - ask Prawn [img]images/graemlins/jump.gif[/img]

[Cobstar]

Hi Jeff

So that's what they mean by every cloud has a silver lining? A justifiable reason to go for more power [img]images/graemlins/smile.gif[/img]

[jeffw]

Update on the Update....part deux

It transpires that the part of the center box of the exhaust has collapsed and, it would appear, caused the turbo failure....


Umm

[Golich]

Now that is interesting. A month after I had my S4 chipped by AMD I suffered a couple of occasions where it seemed the boost had dropped.

I had Jim at Star Performance check the car over i.e. rolling road test. Yup, the car was only putting out 250bhp. At the time the car was calling for more boost but wasn't getting it according to the VAG diagnostic tool. Jim consulted with Scott at AMD but to no avail.

Jim checked for leaks changed out the MAF, N75. Then jacked the car up and tapped the exhaust. The centre section sounded empty where the end box sounded like it was solid.

I get a reverberation off the rear of the exhaust at about 2500 rpm (which I quite like)

On telling Jim this in combination with the above, he thought it might be collapsed baffles in the centre box as he had this problem on seat turbo once with similar diagnostics.

On return to Aberdeen the boost suddenly came back on.

Since then I've experienced the odd occasions of low boost. Which I have so far been unable to diagnose. On occasion the VAG COM has noted the DTC 'boost pressure exceeded - intermittent'
I'm currently looking into testing the DV's by using 'mity vac’s' tester but the UK dealer has still to get back to me. Partco’s testers start at £60 and go up to well over £100, which is too much for an occasional tester that I know I can get for much cheaper. Mity VAC does a plastic pump for I reckon considerably less. Audi world has the article on testing DVs. The other thing I’ve ordered is a boost gauge. APR vent type. Didn’t realise the gauge wasn’t back-lit though until the recent boost gauge post - doah!

I may well look into getting a Miltek CAT back. Although until otherwise proven, I personally think there is little benefit in this alone without the high flow CATS. I’ll see if Milltek will provide their exhaust on the results of a rolling road test. If I notice their claimed minimum increase in power on fitting their exhaust, I’ll buy it. Otherwise they are just selling me a stainless exhaust no better than my original. Hhhmm lets see how that goes for this weekends service. Rolling road and alignment and fitting the RS4 suspension.

[Dippy]

Golich,
Yet again the usefulness of a boost gauge is demonstrated.

I don't know much about exhaust problems, but I would guess that in order to really damage a turbo, it would need a bad block so that the backpressure is quite high AND the turbos being really stressed. Thus Jeff's track-day experience seems understandable, but not so yours.

Low boost problems are most typically air leaks, but your intermittent high boost DTCs suggest DVs which are not opening quickly enough.

I'll just get on my soap-box [img]images/graemlins/soapbox.gif[/img]

Chipping an S4 increases the risk of turbo failure. The most likely cause of premature turbo failure is turbo stress, which again is most likely from air leaks, when a lot of boost is demanded. So IMO if you chip your S4 you should check/uprate the air intake system (as a minimum renew TBB and DVs), but also get a boost gauge!

With respect to the Miltek I agree with you: All or nothing. The value of the full Miltek is clear to me. Without it, as you know a chipped S4 still starts to run out of puff in the top part of the rev range. However with the full Miltek (and a remap) the car still pulls strongly all the way to the red line.

[Golich]

Hmm Dippy, you've confirmed what I've thought about those Hyperboost DV's and the Millteck exhaust.

I spoke to Jim at Star performance again this week and he has his suspicions about the stiffness of the spring in the Forge and Hyperboost DVs for chipped S4's.

He reckons the standard Bosch DV spring is much stronger. He's chatting to them about it. So in the meantime he's going to try a couple of Bosch DVs tomorrow to see how this effects things. [img]images/graemlins/1syellow1.gif[/img]

On the exhaust point. I spoke to Milteck's General manager about supplying a CAT back exhaust on the proviso that I'd buy it if upon running a before and after rolling road I noticed a 5 to 8hp or torque increase. (I realised that there was no way their exhaust was going to give an 8-10% increase as claimed on their current web page.. [img]images/graemlins/3flypigs.gif[/img] hhmm me thinks the trade description act could come into play!)

Anyway, I explained to the GM Dave ?? something, that I was very cynical about these so called performance exhausts and I could see no point in throwing away my perfectly good substantial aluminium thermally sprayed stock CAT back system for £450 worth of stainless steel. However, if there was a slight improvement in power/torque, throttle response etc. I'd have it. But I didn't want Jim to buy the exhaust and then I find out there is no improvement and refuse to take it leaving Jim with a £450 exhaust.

Well, Dave said prior to calling he could find no info relating to power gains etc. All he claims to have found is some literature that suggested the exhaust was developed in conjunction with MTM.

He suggested I speak to Scott at AMD who would confirm it's performance improving capabilities. I said "Ahem well yes.. I know what Scott will say, he tried to sell me one the time I had my car chipped by THEM! and I told Scott then what I'm telling you now is it really value for money?"

"Despite the sale chat before and after power curves I have yet to see a power curve that truly differentiates the improvement from fitting ANY so called performance exhaust from the CAT back and lets face it these things are not cheap!"

I told Dave if you have confidence in your product as marketed then you will have absolutely no reservations about sending an exhaust to Jim on the proviso he can send it back if it doesn't do as you say it does."

I also added that as a subscriber to Audi driver and RS246 and audi-sport.net etc this is a great advertisement opportunity. Or on the flip side it could also be bad publicity if it didn't!"

The upshot... he talked to Jim... no one called me back. I called Jim the next day.

Millteck were not prepared to take the gamble - As far as I'm concerned this confirms exact what I've always thought WASTE OF MONEY and a load of BS [img]images/graemlins/033102ass_1_prv.gif[/img], "it's all or nothing" to quote Dippy.

That’s me off my
[img]images/graemlins/soapbox.gif[/img] [img]images/graemlins/rant.gif[/img]

What a great couple of thingy_me_jigs these new ones are [img]images/graemlins/jump.gif[/img]
[img]images/graemlins/yellows4.gif[/img]

[Dippy]

Interesting.

However I was suggesting that the DVs were not opening quickly enough, which would be due to springs being too stiff, not too weak. Or more likely that the pistons are not sliding well and they need some maintenance.

Yes the standard springs in the Forge DV007P DVs are 'weaker' than the standard Bosch units. However I checked this with Forge and they confirmed that they are the correct springs for a chipped S4.

Based on my 'armchair engineering' I can see that for higher boost/airflow cars, stiffer springs may be needed to counteract the air resistance to make the DV close quickly. But the downside is that the DV will open more slowly resulting in boost spikes.

The reason I prefer the Forge DVs is that they have solid metal pistons. The Bosch valves have flexible diaphragms which can tear. If you go for Forge DVs but have a stiff spring then you have swapped one risk for another: The boost spikes can cause ruptures elsewhere in the system (especially a TBB!).

Nevertheless I'd be keen to hear what Jim says on the subject.

[Golich]

On my way to Star performance on Sat to get the car chipped the car was running great despite the unusually hot weather in bonny Scotland 22DegC. [img]images/graemlins/grin.gif[/img]!

When 3 miles from Star performance the boost went. (just as it has on a couple of occasions.) [img]images/graemlins/confused.gif[/img]

VAG tool diagnosed the usual "exceeded boost..." So as discussed with Jim he was going to try a couple of standard Bosch DV's until he discovered he only had one! [img]images/graemlins/frown.gif[/img]But on looking at my own fitted by AMD he thought the vacuum hose looked kinked as it was too long and decided to cut it back to remove the kink. Something I had noticed before but never really got round to doing anything about.

We did the dyno run 302bhp and 384ftlbs. Nothing wrong there.

We took the car out for a spin and the boost was running 1.1 with a 1.3 spike, which is normal for an AMD map (apparently).

Anyway he thought that maybe the vacuum has been restricted which has caused a boost spike as one DV was unable to open. Depending on the map the ECU will shut down the boost to a safe level and again depending on the map the resulting DTC has either to be cleared via VAGCOM etc. or a couple of pumps of the throttle will reset the ECU to allow full boost. I've noticed both results.

Anyway, he's has his suspicions about the hyperboost/Forge DV's and on talking to APR USA he discovered they are interestingly recommending standard bosch DV's with their RE-maps.

He tried one of Hyperboosts adjustable DVs but didn’t like the resulting strange power curves. Now I must admit at that point I wasn’t fully listening to him as I was thinking about other things. The upshot is, at the mo, he’s all for sticking with the bosch DVs as they are only £17 each and surely you will get 6months out of them.

I need to talk to him about this again but in the meantime I’m going to try stock bosch units to see if I’ve still got that slight lag on changing gears.

PS I had an advanced driver track day at Knockhill I expected the car to boost spike - no probs so the kinked hose way well have been the problem. [img]images/graemlins/boots.gif[/img]

PPS Top service carried out by Jim. Full 20k service for £270 including rolling road. Fiddling with the DVs and a new rear wiper blade and road test to measure the boost pressure / ECU. [img]images/graemlins/clap.gif[/img] His lad discovered the last independent to service my car only changed 4 of the 6 spark plugs! Wait to I get those tossers - £47 for those platinum babies! [img]images/graemlins/rocketwhore.gif[/img]

[Dippy]

Thanks for the update.

Yes the AmD S4 map will give a peak overboost of about 1.3 bar and then settle to around 1.1 bar. I like this because at 1.3 bar the K03 is really maxxed out and shouldn't really do it for long!

The 'kink' you refer to is on the driver's side DV. The Forge (& Hyperboost) units are bigger than the Bosch and this causes the hose to do a rather tight 'S' shape. When I fitted my APR bipipe I adjusted the other hoses to relieve the stress on the vacuum hose as much as possible.

Yes I can believe that if your vacuum hose had been restricted you could have experienced boost spikes and the ECU going into limp mode.

So the jury is still out on the DVs?
I'll point out again that AmD fitted my Forge valves at the same time as the remap, so they must think they're OK. Plus I did ask Forge, and they told me that I had the right springs. Forge are known for their excellent customer service and will send you new springs at the drop of a hat. So if they think I have the right springs then I trust them.

Besides I have been experimenting with apparent lag on my car. I have found that when I change gear on 'moderate boost' e.g. 0.6 bar, there is no lag. I could believe that the ECU itself decides to hold the DVs open for a bit longer after higher boost in order to ensure that there are no spikes???

Anyway I'll still be very interested to hear your experience of switching to Bosch DVs.

Good news about Star, but unfortunately a bit far for me to go for a service! I had been thinking of asking for my old spark plugs to be returned to me at my next service, and your tale suggests that this is a good idea!

[Golich]

Watch this space. (I just noted my previous post said I was going to get my car chipped. I was actually getting a 20k service!)

[jeffw]

Right then.....got the car down to AmD for it's 'final' remap today....and the scores on the doors are

395bhp
473 lb/ft

Given the temperature today I thought that was pretty good [img]images/graemlins/cool.gif[/img]

[Prawn]

Damn !!!! were did you get that extra 23lb/ft from (mines at 450) [img]images/graemlins/nodder.gif[/img]
How does it feel then Jeff ?

[jeffw]

It's err.....quick [img]images/graemlins/cool.gif[/img] [img]images/graemlins/acclaim.gif[/img]

AmD reckon that it would see over 400 bhp if the temp had been lower.....