Decoking...

[klauster]

all my info plots and data have been given to Audi technical - Germany, Audi York awaiting a response on how to go forward...

[karl]

Right ive been thinking about the dreaded coking up issue. SO......

Audi developed and designed this engine,now correct me if i,m wrong but surely it was tested over thousands and thousands of miles both in a car and probably in a lab some where hooked up to all kinds of dianostic equipment?
So surely after extensive testing etc they stripped these engines down and inspect wear,tear deposits etc?? this must be common practice among all car/engine companies? to check on all kinds of perameters etc.

SO

If that was the case and i think it will of been and still is, Audi would have seen the carbon deposits on not just this engine but many others(FSI) and be aware of it?? This tells me they dont see it as a issue that can cause problems or surely they would not have dared develop the engine due to the financial backlash if nothing else.
I dont think this is causing the BHP issues although a lot of the discussion on this forum regarding BHP/deposits etc etc is a little above me as i am not techincally minded!!!

All i know is my car is quicker now than its ever been(17000miles) and long may it continue(que someone saying yeah but how long for??).
All i,m saying is i dont believe for one moment the VAG group has not carried out enough development on FSI engines as to not be aware of the deposit issues or be worried about them.

Nor am i an expert on rolling roads etc but i,d say if you took the engine from the car and tested it without drivetrain i bet it would be producing 400bhp end of(as long as it was maintained properly).

And finally,

If this is a long term problem why oh why are Audi using the same engine in the RS5?? Surely again if they were worried theyd develop a different engine???

Long live the RS4!!! ENJOY THEM WHILE YOU CAN.

The issue is definately affecting/causing a loss in BHP/torque to some degree. Simply looking at the ever increasing number of 'unoffical' pictures showing the inlet valves will tell you flow must be affected and the findings MRC made with my car back this up. Wether or not Audi chose to recognise this is another matter........I have also heard of a car where the build up was so bad it was causing one of the valves not to seal in the head

We still don't know just how quickly the build up occurs, how much it takes to impact performance and whether after a certain amount the performance drop levels off.

We should hopefully be able to answer a few of these soon as I'll be off to MRC again for them to measure buildup after 2kish, clean up where necessary, and fit a custom filtering/cleaning system that should solve this (for me a least ) once and for all.


As for why use the same engine in the RS5 - we have yet to see if they use the same EGR system and 'cyclonic separator..' and remember, DRC was failing a long time before the B7 appeared.

Yes Rob - that was my car with the non-sealing valves! I would never have known about it if I hadn't had the work done!! Surely Audi have a responsibility here?!!

[ArthurPE]

why is the TN factor (overall gear ratio used to calculate engine torque from measured wheel torque) different for each run?
same dyno machine
same cf, 'shoot 44'
same gear, 4th?
note: this only compensates for the gears torque multiplication, NOT losses...

if you adjust the curves for the same TN, they are very close...

klauster 3.242
P G 3.545

3.242/3.545 x 367 HP at 7600 rpm = 335
on the lower graph HP at 7600 ~325...
using an average of 330 and 20% losses, HP ~ 413...

if we use the HP at 5252, ie, where HP and T are equal...
1st graph 265
2nd, 290

adjusting:
3.242/3.545 x 290 = 265...identical

something's not jiving

[klauster]

i havent got a clue why they are different, my runs were in 4th, with esp off etc.. and S button on

[Andyuk911]

Ok, posted before .. but I won't leave on here long ..my car has no remap ....

[P_G]

Do you remember in which gear Andy?

[Andyuk911]

At wheel numbers, so what the dyno actually saw ..

[Andyuk911]

Do you remember in which gear Andy?

Sorry don't know, SR71 might know

[pippyrips]

If it was Surrey RR i'm pretty sure it will be 3rd.

[silverRS4]

Doesn't matter which gear really in this case. Both klauster's and PG's curves are not what they should be. Andy's is the what the curve should look like, practically flat from 3000-5000 RPM and then an abrupt torque peak around 6000 RPM and then a regressive downward curve. If you find any literature published by Audi (such as the European RS4 brochure or the 4.2FSI RS4/Q7 Training manual), that is what it looks like. That is exactly what my curve looks like. Call it a signature. There is no reason not to expect the "profile" curve output of a healthy RS4 to be any different than the "profile" published by the automaker. In my opinion, klauster's and PG's profiles are seriously poor. Careful diagnostics should uncover something.

[ArthurPE]

those graphs both show the same cf 'shoot 44'

here's the cf's:
rpm(x 1k).....HP(%).....T(%)
2...................25...........32
3...................31...........30
4...................33...........29
5...................29...........25
6...................28...........27
7...................27...........24
8...................30...........27

they should be identical for HP and T since they are linearly related
T = HP x 5252/rpm, so for the same rpm (it cancels) the cf should be the same

eg, at 5252 rpm
HP....232....297...cf = 28%
T......232....297...cf = 28%

but it should match everywhere...

honestly, the more I see re: dyno's, the more I doubt their worth...the only true tests, top speed and 1/4 mile et & trap speed...

[P_G]

Doesn't matter which gear really in this case. Both klauster's and PG's curves are not what they should be. Andy's is the what the curve should look like, practically flat from 3000-5000 RPM and then an abrupt torque peak around 6000 RPM and then a regressive downward curve. If you find any literature published by Audi (such as the European RS4 brochure or the 4.2FSI RS4/Q7 Training manual), that is what it looks like. That is exactly what my curve looks like. Call it a signature. There is no reason not to expect the "profile" curve output of a healthy RS4 to be any different than the "profile" published by the automaker. In my opinion, klauster's and PG's profiles are seriously poor. Careful diagnostics should uncover something.

You say all that but my car feels fine. Also fundamental maths regarding graphs, the longer the x-Axis the more elongated the results. I have noticed this on a number of r/r results that the x-axis increments are far greater than what mine have been, klausters is even more graduated then mine.

[Andyuk911]

Arthur, agree and understand.. However as Silver already said, both the others cars are sick and the same with Mac's car ...

I suspect PG if you drove my car you would feel the difference ... RAudiguy's car takes off even more ..

When my car arrives back from the DRC repair, I will try and time a 0-100mph at Brands Hatch.

[klauster]

is there any reason why 2 cars, would produce completely different numbers on a dyno other than actually being down on power?

[Dom81]

When my car arrives back from the DRC repair, I will try and time a 0-100mph at Brands Hatch.

Does that mean it's back on the road?