http://www.bobistheoilguy.com/forums/ub ... 333&page=2
Дискутира патент подаден от ФВ за елиминиране на проблема
"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. "
Второто дискутира наличието на проблема в настоящето поколение двигатели и дали/как ще се реши в следващо поколение ДИ
http://forums.vwvortex.com/zerothread?&id=4397707
It seems as though more and more cases are popping up where direct injected engines are experiencing miss-fires, rough running, and reduced power output due to extreme levels of carbon buildup on the intake valves. Audi's 4.2 FSI V8 and 5.2 FSI V10, VW's 2.0T, and Porsche's 4.8 DFI V8 are known victims so far...
Presumably, this is because normal port-injected engines have the added benefit of washing away any deposits that may form with the fuel spray. Unfortunately direct injected engines have no way of clearing off deposits and thus need to go in periodically to have the valves cleaned.
Is this a design flaw with direct injection or is there a solution on the horizon? Has anyone had first-hand experience with this phenomenon?
Links for reference:
Audi RS4:
http://forums.audiworld.com/sh...build
Porsche Cayenne Turbo:
http://www.planetporsche.net/c....html
Modified by greatfox at 12:26 PM 5-19-2009
Дали някой от знаещите би коментирал доколко този проблем е реален? В горните теми се твърди, че едва ли не на 100К км проблемът е гарантиран, цитират се случаи още на 10К км...
Карана е само с Шел / по задължение -Еврошел карта/ .Не , че и на другите вериги горивата са цвете.По лопатките имаше отлагания.Скъсана ос на турбото . Колата умря на 15м след светофар и стана недвижимо имущество.
Защо си мислиш така ?? Не се даваме на Туарег по завоите .На дълги прави туарега издъпва , но пак сме зад него.