Valves- carboning up

[aidanjaye]

If you want some idea of what is involved, have a look at this thread on 3.2 V6 FSI engine:
link

Cheers for that.

Anyone used BG44K Pro Grade Fuel Injector & Fuel System Cleaner, as mentioned in the above link. Obviously the makers will say it "sh*t hot" but would be interested to here if others have used.
Seem to recall someone did you some kind of additive in their RS4? If no one remembers , I'll trawl the search function.

[silverRS4]

This is what the valves look like after a chemical fog. I normally clean by hand, but wanted to see how well this worked. The initial buildup was much less than OP's and the fog did basically nothing except maybe soften the crud. Waste of time. There is no motive force to get the crud off the valves. They need to be cleaned by hand. The BG 211 ISC (Induction System Cleaner) is the most agressive chemical they have, specifically for carbon buildup. The apparatus is pressurized at 60 psi and the chemical is fogged into the intake through the nozzle. Both Wynn's and BG have marketing saying they can clean DI valve deposits with this method. I don't think so. BTW Art, who says the sky is falling? I love my RS4 and will have it for a long time. I can remove my manifold and clean the valves in about the time it takes you to piss off people on three continents. If an RS4 owner wants to leave their valves alone or thinks its not an issue, good for them. But if an owner wants clean valves, or a detailed car or fresh brake fluid, or whatever - I think they can decide for themselves.

[aidanjaye]

Cheers silverRS4, thought it would have been to good to be true / to easy a solution.
Until I notice any probs, will just live with it.

Interestingly some cars use a lot more oil than others - is there a possibility that some cyclic filter thingys may be crap??

My car uses no oil and doesn't smoke and at nearly 34000 miles, still pulls well with a decent kick at 5500rpm.

[2manytoys]

^^ Just curious, what type of driving do you do and what oil do you use?

Thanks, Mal.

[ArthurPE]

2manytoys;

Does your car see extended operation at 3000rpm or above?
By extended, I'm referring to the 20min that is referenced in the patent document.

Arthur,
As I mentioned, I didn't expect there to be an object in place to wipe the valves as they rotate.

With respect to the wiping of the valve seat as a natural consequence of the valve's rotation, the effects of the rotational wiping are minimal.

Is the wiping effect not created by a different angle of valve and valve seat - causing increasing flow of gases to do the wiping effect as the valve closes. The rotation of the valve has nowt to do with the wiping effect IMO. I could be wrong.

the angle would promote the natural tendency to rotate...
read the VW/AUDI patent...valve 'wiping' has significant effect, they rotate 360 deg every 200 rpm or so...a couple of degrees every rev (at least)

so at 3000 rpm they rotate 15 times in 1 minute...or once every 4 sec...very significant...in 1 hour of driving 900 revolutions
remember, when they open they are also scoured with hot exhaust gas being sucked into another cylinder...

almost every bad case of deposits (every one I could find) was accompanied by another failure, usually the manifold flaps, and as stated in the patent, they are critical for alleviating (minimizing, you will always have some) deposits

[ArthurPE]

Seems strange why the valve stem is wet but the actual block seems relatively dry?? My first thought was leaking valve stem seals.

I wondered the same, something seems to be exasperating the issue...
no way will deposits alone cost 40% of the power (~330 to ~195 rwhp)
especially the curve (or flat line) nature of the power delivery (or lack there of), almost like a 'limp mode'

the stuff I've read, even with severely occluded valves state a range of 5-10%...again, the torus formed by the opening is >>> larger than the valve seat circular opening, deposits have (relatively) little impact on air flow...
generally 10% is considered not significant, atm conditions/fuel/etc. have as much or more impact...

also, the air is being pumped (sucked/vaccumed) into the cylinder, so ~ the same volume will be inducted, pumping losses will increase, meaning more HP (marginally) is required to move the same volume of air...it's like ANY positive displacement pump

[sonny]

If you want some idea of what is involved, have a look at this thread on 3.2 V6 FSI engine:
link

Cheers for that.

Anyone used BG44K Pro Grade Fuel Injector & Fuel System Cleaner, as mentioned in the above link. Obviously the makers will say it "sh*t hot" but would be interested to here if others have used.
Seem to recall someone did you some kind of additive in their RS4? If no one remembers , I'll trawl the search function.

I believe it was Andy911UK

[ArthurPE]

imho flushing with solvent may cause more problems...gobs clogging convertors, fouling plugs, etc.
I think the deposit qty will equalize/stabilize in a properly functioning engine, and will not be noticeable by performance parameters, they only look bad when you look at them...

my car has 25k, never been cleaned, and runs like a raped ape...3k-8k 8 sec 3rd, same as road tests using ALL gears...
as long as it's running like this, I have 0 desire to inspect the valves...

I do take precautions:
5-6k oil changes
Shell 93
use the highway (vs town roads) when I can, my work route same time via town or HW (12 min), HW is a bit longer, but car gets hotter and runs consistently at a higher rpm
run ~ 3000 rpm until warm, run it thru the gears to 7000 frequently...from a stop to 60, to 7000 in 1st/2nd, short shift to 5th, or whatever...

[ArthurPE]

And I take it the job is out of scope for the DIYer?? Not had a look but has anyone considered it?

I'm sure you could do it, access is straightforward, solvent & scrubbing is a pita...do it over a week end so you can let the solvent set and you are not rushed...

one word of caution: the valves have a special surface treatment applied, abrasive action may damage it and make the fouling worse...

[silverRS4]

almost every bad case of deposits (every one I could find) was accompanied by another failure, usually the manifold flaps, and as stated in the patent, they are critical for alleviating (minimizing, you will always have some) deposits

You're not looking hard enough, and what you are finding you are interpreting incorrectly. Three cases that I can think of immediately, the owner had zero CEL's and no indication of a problem. They had no vacuum problems, no flap problems, not even 1 misfire, zero. Only consistent complaint was loss of top end power. In all three cases, the CB is removed (all else is the same) and the normal power character returns (along with 20-40 hp due to the ignition retardation decreasing normal levels). All had CB. Then, lets mention that EVERY RS4 that has had its manifold off has revealed some CB. That number must be close to 20 across all the forums. That does not include all the 2.0 and 3.6 FSI's. Yes, the manifold removal may have been necessitated for another problem. Stuck flaps (due to carbon) or bad injectors (due to carbon). You're saying the secondary problem causes (or worsens) the CB, when actually the CB is there all along and it takes a secondary problem for Audi to actually remove the manifold and see the CB. After 8k miles without the vanes, my valves were as cruddy as they were after 8k with the vanes. The patent seems to have more to do with valve surface treatment anyway - not really the scraping mechanism. Is it possible the surface treatment portion of the patent isn't even in production yet? The one thing made clear from the patent is that CB is a problem with direct injection - hence the tremendous effort to resolve it. Some DI cars see the CB at an advanced rate. For whatever reason (probably the more aggressive valve overlap and higher intake valve temps) the RS4 can see accelerated CB compared to the other VAG DI engines. Minor CB does not create a terrible problem. But eventually the ignition timing is no longer optimal and power (especially top end) will suffer.

[ArthurPE]

almost every bad case of deposits (every one I could find) was accompanied by another failure, usually the manifold flaps, and as stated in the patent, they are critical for alleviating (minimizing, you will always have some) deposits

You're not looking hard enough, and what you are finding you are interpreting incorrectly. Three cases that I can think of immediately, the owner had zero CEL's and no indication of a problem. They had no vacuum problems, no flap problems, not even 1 misfire, zero. Only consistent complaint was loss of top end power. In all three cases, the CB is removed (all else is the same) and the normal power character returns (along with 20-40 hp due to the ignition retardation decreasing normal levels). All had CB. Then, lets mention that EVERY RS4 that has had its manifold off has revealed some CB. That number must be close to 20 across all the forums. That does not include all the 2.0 and 3.6 FSI's. Yes, the manifold removal may have been necessitated for another problem. Stuck flaps (due to carbon) or bad injectors (due to carbon). You're saying the secondary problem causes (or worsens) the CB, when actually the CB is there all along and it takes a secondary problem for Audi to actually remove the manifold and see the CB. After 8k miles without the vanes, my valves were as cruddy as they were after 8k with the vanes. The patent seems to have more to do with valve surface treatment anyway - not really the scraping mechanism. Is it possible the surface treatment portion of the patent isn't even in production yet? The one thing made clear from the patent is that CB is a problem with direct injection - hence the tremendous effort to resolve it. Some DI cars see the CB at an advanced rate. For whatever reason (probably the more aggressive valve overlap and higher intake valve temps) the RS4 can see accelerated CB compared to the other VAG DI engines. Minor CB does not create a terrible problem. But eventually the ignition timing is no longer optimal and power (especially top end) will suffer.

according to you...I'll trust my judgement and skill set over yours, no offense...I know mine, and don't know yours...

I do know when you 'google' the issue 4 names are always present:
yours, RI RS4 (now RI A6 iirc, amongst others) and 'bob the oil guy', along with biosyn...

what the patent does (EVERY patent) is states the problem (that is required by law), and then the solution they are trying to patent...sometimes the problem is overstated to increase the proprietary nature and value of the solution...ie, justify the patent...

people have been (mis)using, disingenuously imo, the problem statement portion of the patent application as 'proof' VAG is 'aware' of the issue...heck, any engine engineer worth spit would know that valve deposits are a factor and need addressed in any design!
it's like telling an EE voltage drop must be considered in power engineering, lol

interesting trivia: in the US patent attorneys must also be licensed PE's

[MarkD]

what the patent does (EVERY patent) is states the problem (that is required by law), and then the solution they are trying to patent...sometimes the problem is overstated to increase the proprietary nature and value of the solution...ie, justify the patent...

people have been (mis)using, disingenuously imo, the problem statement portion of the patent application as 'proof' VAG is 'aware' of the issue...heck, any engine engineer worth spit would know that valve deposits are a factor and need addressed in any design!

Given the "Background of the Invention" paragraphs covered in the patent document you linked, specifically;
The second paragraph which comments on the cause of the carbon build-up: "A more exact analysis of how these carbon deposits form leads to the following result: .....These constituents are chiefly ..... low-volatility components of oil and fuel", and the third paragraph which comments on effect: "the coating of carbon deposits in the neck region of the intake valve causes flow resistance, which can lead to significant performance losses due to insufficient cylinder filling, especially in the upper load and speed range..."

I think Volkswagen is well aware of the issues that exist with DI engines, as it relates to carbon buildup.

[ArthurPE]

what the patent does (EVERY patent) is states the problem (that is required by law), and then the solution they are trying to patent...sometimes the problem is overstated to increase the proprietary nature and value of the solution...ie, justify the patent...

people have been (mis)using, disingenuously imo, the problem statement portion of the patent application as 'proof' VAG is 'aware' of the issue...heck, any engine engineer worth spit would know that valve deposits are a factor and need addressed in any design!

Given the "Background of the Invention" paragraphs covered in the patent document you linked, specifically;
The second paragraph which comments on the cause of the carbon build-up: "A more exact analysis of how these carbon deposits form leads to the following result: .....These constituents are chiefly ..... low-volatility components of oil and fuel", and the third paragraph which comments on effect: "the coating of carbon deposits in the neck region of the intake valve causes flow resistance, which can lead to significant performance losses due to insufficient cylinder filling, especially in the upper load and speed range..."

I think Volkswagen is well aware of the issues that exist with DI engines, as it relates to carbon buildup.

that was my point:
as would be any automotive engineer...in fact that is one of the the purposes of the patent: to protect methods to deal with such things in a DI engine...1 they are aware of the issue 2 this is how they propose to deal with it, and 3 they want to legally protect their 'invention' or methods and intellectual property...

which tells me this has gotten a lot of attention from them, for a long time, and they have developed and implemented measures to deal with it, a primary reason I do not believe it to be the problem others do!
they didn't 'miss' anything and have 'worked' the problem...examples:
valve coatings
cycle overlap
intake flaps
cyclone seperator
etc.

and btw the quoted verbage applies to ANY combustion engine...

note also the word 'can', not shall or will, nor is the word 'can' omitted, which means it 'may', not will...this is not an accident, this is legal jargon...

although 40% imo is a littel too significant...most stuff I've read put losses to extreme occlusion at 5 to 10%

[2manytoys]

Ok, it's now clean





The power difference again is amazing. While there was a noticable difference at about 6k after Audi "cleaned" the intake, now there is a significant power surge from about 5.5k rpm and can only be described like having turbo's.

Guys, this power difference, and power delivery is amazing. It pulls VERY hard!

I'll have it back to the Dyno within a couple of weeks and show you the real numbers.

Unless something else broke, I'd probably say all our RS4's are effected by this, either a slight carbon build up, or major like mine. When a 4.2 Ltr makes ~420hp, and needs to rev to 8k, the intake needs to be up to sratch to see all the power.

Stay Tuned

Mal.

[S2tuner]

Glad to hear all is good Mal, however I'm sure ArthurPE will chime in again to claim that any gains you feel are bogus