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#1414263 - 03/25/09 09:44 AM Acknowledgement of the Audi/VW FSI Deposit Issues
RI_RS4 Offline


Registered: 07/18/06
Posts: 1175
Loc: Rhode Island
Directly from the technical staff of VAG is complete acknowledgment of the FSI intake valve deposit issue, and it's impacts, including: decreased performance, misfires, catalytic converter damage ... etc.

VW Patent on "Direct Injection Internal Combutstion Engine"

 Quote:
"Gasoline engines with direct injection of the fuel into the combustion chamber, i.e., not into the intake port, suffer especially from the problem of the formation of carbon deposits on components. Carbon deposits form especially in the neck region of intake valves. A more exact analysis of how these carbon deposits form leads to the following result: Oil and fuel constituents first form a sticky coating on the components. These constituents are chiefly long-chain and branched-chain hydrocarbons, i.e., the low-volatility components of oil and fuel. Aromatic compounds adhere especially well. This sticky base coating serves as a base for the deposition of soot particles. This results in a porous surface, in which oil and fuel particles in turn become embedded. This process is a circular process, by which the coating thickness of the carbon deposits continuously increases. Especially in the area of the intake valves, the deposits originate from blowby gases and from internal and external exhaust gas recirculation, and in this process, the blowby gasses and the recirculated exhaust gas come into direct contact with the intake valve."

"Especially in the area of the neck of the intake valves, excessive carbon deposits have extremely negative effects for the following reasons: In the case of Otto direct injectors, the successful ignition of the stratified charge depends to a great extent on the correct development of the internal cylinder flow, which ensures reliable transport of the injected fuel to the spark plug to guarantee reliable ignition at the spark plug. However, a coating of carbon deposits in the neck region of the intake valve may interfere so strongly with the tumble flow that ignition failures may occur there as a result. Under certain circumstances, however, ignition failures can lead to irreversible damage of a catalytic converter installed in the exhaust gas tract for purifying the exhaust gas. Furthermore, 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 of the internal combustion engine. In addition, the carbon deposits in the neck region of the intake valve may prevent correct valve closing, which leads to compression losses and thus sporadic ignition failures. This in turn could irreversibly damage the catalytic converter. There is the potential for small particles to break away from the coating of carbon deposits in the neck region of the intake valve and get into the catalytic converter. These hot particles may then cause secondary reaction and corresponding local damage of the catalytic converter. For example, a hole may be burned in the structure of the catalytic converter."

"Globular deposits are found especially on the valve stem downstream from a partition plate in the intake port. Due to the dripping of high-boiling hydrocarbons from the partition plate towards the valve neck or valve stem, globular carbon deposits eventually form there by the sequence of events explained above. These deposits on the valve stem can result in flow deficits due to undesired swirling and turbulent flow around the globular carbon deposits. This may persistently interfere with the formation of stable tumble flow from cycle to cycle."

"A possible solution would be to keep these sources of deposits away, for example, from the intake valve, by completely eliminating exhaust gas recirculation and the introduction of blowby gases into the intake port. However with the combustion behavior of modern reciprocating internal combustion engines, at least external exhaust gas recirculation and the introduction of blowby gases into the intake port are absolutely necessary for reasons of emission control and fuel consumption, so that this approach is not possible. "

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#1414270 - 03/25/09 09:55 AM Re: Acknowledgement of the Audi/VW FSI Deposit Issues [Re: RI_RS4]
d00df00d Online   content


Registered: 10/20/05
Posts: 9218
Loc: PA
Is this their first official acknowledgment?
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#1414276 - 03/25/09 10:01 AM Re: Acknowledgement of the Audi/VW FSI Deposit Issues [Re: RI_RS4]
Johnny Offline


Registered: 05/27/02
Posts: 14013
Loc: Retired | Wausau, WI
It looks like this patent was filed in 2002 and issued in 2005. So what have they done in the past four years to solve this issue?

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#1414317 - 03/25/09 10:46 AM Re: Acknowledgement of the Audi/VW FSI Deposit Issues [Re: Johnny]
G-MAN Offline


Registered: 11/15/02
Posts: 8869
Loc: SC
Could they not cure the problem by putting a secondary fuel injector at the end of each intake runner (roughly where the injector would be on a normal EFI set up) to inject a small amount of gasoline that would wash the intake valve on the intake stroke?
_________________________
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#1414326 - 03/25/09 10:56 AM Re: Acknowledgement of the Audi/VW FSI Deposit Issues [Re: G-MAN]
RI_RS4 Offline


Registered: 07/18/06
Posts: 1175
Loc: Rhode Island
They could, but I believe the patent belongs to another company.

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#1414328 - 03/25/09 10:56 AM Re: Acknowledgement of the Audi/VW FSI Deposit Issues [Re: Johnny]
RI_RS4 Offline


Registered: 07/18/06
Posts: 1175
Loc: Rhode Island
Heck, they don't even acknowledge it as being a problem at the dealer service level. It does not appear that this new valve design has gotten into production yet.

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#1414333 - 03/25/09 11:03 AM Re: Acknowledgement of the Audi/VW FSI Deposit Issues [Re: RI_RS4]
G-MAN Offline


Registered: 11/15/02
Posts: 8869
Loc: SC
 Originally Posted By: RI_RS4
They could, but I believe the patent belongs to another company.


They could patent the secondary injector "cure" and get a whole new patent on the entire set up. \:\!
_________________________
2010 Audi A4 2.0T Quattro: RLI 5w40 HD Low Ash
2004 Ford Crown Vic: MaxLife 5w20

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#1414334 - 03/25/09 11:05 AM Re: Acknowledgement of the Audi/VW FSI Deposit Issues [Re: G-MAN]
SamSpade Offline


Registered: 08/23/08
Posts: 86
Loc: Philippines
 Originally Posted By: G-MAN
Could they not cure the problem by putting a secondary fuel injector at the end of each intake runner (roughly where the injector would be on a normal EFI set up) to inject a small amount of gasoline that would wash the intake valve on the intake stroke?


That would be acknowledging that FSI isn't ready for primetime and port FI is still the way to go. And of course, adds complexity.

The solution is an exceptionally good PCV system with a redesign of the path the crankcase fumes goes through the intake. I'm sure they'll figure it out eventually.

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#1414337 - 03/25/09 11:06 AM Re: Acknowledgement of the Audi/VW FSI Deposit Issues [Re: RI_RS4]
saaber1 Offline


Registered: 11/28/07
Posts: 1877
Loc: Pacnw
Wow, fantastic info!

After RL_RS4's last post showing the deposits on the Euro car, I requested a bid to convert my pcv system to a "slashcut" system, which will send pcv gunk to the exhaust and not to the intake manifold. Simple and effective solution and cranckase gases are still pulled out under vacuum.

_________________________
"when 5W30 is cold, ...the oil is 35 weight (5+30),...20 w 50 starts at 70 and warms up to 50"
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#1414352 - 03/25/09 11:20 AM Re: Acknowledgement of the Audi/VW FSI Deposit Issues [Re: saaber1]
G-MAN Offline


Registered: 11/15/02
Posts: 8869
Loc: SC
This is a classic case of a system designed for the race track having problems in the "translation" to street use.

Anyone who has ever looked at the inside of a typical port injected/EGR intake manifold upstream of the injectors would have been able to predict this problem. The same sort of deposit accumulation, except with DFI all the way to, and including, the intake valves.
_________________________
2010 Audi A4 2.0T Quattro: RLI 5w40 HD Low Ash
2004 Ford Crown Vic: MaxLife 5w20

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#1414399 - 03/25/09 11:56 AM Re: Acknowledgement of the Audi/VW FSI Deposit Issues [Re: G-MAN]
zoomzoom Offline


Registered: 08/20/03
Posts: 799
Loc: Washington, DC
hehe I was right..screw the emissions

"A possible solution would be to keep these sources of deposits away, for example, from the intake valve, by completely eliminating exhaust gas recirculation and the introduction of blowby gases into the intake port. However with the combustion behavior of modern reciprocating internal combustion engines, at least external exhaust gas recirculation and the introduction of blowby gases into the intake port are absolutely necessary for reasons of emission control and fuel consumption, so that this approach is not possible. "

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#1414465 - 03/25/09 12:53 PM Re: Acknowledgement of the Audi/VW FSI Deposit Issues [Re: zoomzoom]
Jim 5 Offline


Registered: 05/25/05
Posts: 4009
Loc: Calgary Canada
What about an physical EGR block-off with an aftermarket software upgrade to make it work?

This is exactly what the turbodiesel guys do. If I'm not mistaken, there is plenty of aftermarket to achieve this for those turbodiesel trucks.
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07.5 GMC Sierra 2500HD LMM Rotella 15w-40
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#1414600 - 03/25/09 03:06 PM Re: Acknowledgement of the Audi/VW FSI Deposit Issues [Re: G-MAN]
mechtech2 Offline


Registered: 09/05/06
Posts: 19479
Loc: Chicago Area
A catch can system would be of great benefit to those DI engines.

The problem for a mfr. is that it relies on the consumer to empty it rather frequently. Anything that relies on the consumer is automatically faulty.


Edited by mechtech2 (03/25/09 03:07 PM)

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#1414676 - 03/25/09 04:05 PM Re: Acknowledgement of the Audi/VW FSI Deposit Issues [Re: mechtech2]
zoomzoom Offline


Registered: 08/20/03
Posts: 799
Loc: Washington, DC
RI_RS4 do you have any pictures of your intake valves?

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#1414716 - 03/25/09 04:38 PM Re: Acknowledgement of the Audi/VW FSI Deposit Issues [Re: zoomzoom]
rhouse181 Offline


Registered: 03/07/09
Posts: 22
Loc: Houston, TX
great read! looks like some ammo to use with the VW/Audi service department in future if necessary...

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