AUTOiNFORM ONLINE MAGAZINE: Decontaminating engines cost efficiently

[@Nicoleise]

To my knowledge, it is incorrect to state that the engine does not have an EGR function. While it does not have a psysical valve or flap for that specific purpose, the EGR function persists and is carried out by the intake camshaft variable timing solenoid, which along with a better engine response and a better distribution on torgue, also provides an overlap in valve opening during the exhaust phase of the combustion. This practically means, that when the fuel and air mixture has been compressed, ignited and sends the piston down, the exhaust needs to be evacuated, which happens by opening the exhaust valves as normal. At this very stage, the inlet valves are also opened, when the engine is not under full load conditions or other conditions that prevent EGR from being applied. The solenoid N205 (if memory serves correctly) is responsible for this task, and is controlled by the engine map. This means, that exhaust will flow over the intake valves, along with the oil fumes from the positive crankcase ventilation system, that is induced either pre or post turbocharger inlet depending on engine load. This results in a variable mixture of oil fumes, hot air exhaust gas, even a slight oil leakage around the valve stem (by design), all resulting in a lovely mix of char, soot, fumes, oil and heat. The only thing lacking is fuel to clean it up, since that is injected directly into the cylinder and thus never passes the intake valves before being combusted. This is also the very reason this procedure is even remotely useful. With a multipoint inlet injection, a simple additive in the fuel could aid the situation, but with this configuration, the only remedy is to add a temporary injection point for the mixture manually. Later revisions of this engine have direct+multipoint injections for the sake of driving economy as well as to provide fuel over the valves while EGR is active.

[@foxdmulder]

Why do petrol engines like this suffer from excessive carbon at lower milage on the intake, I always considered it to be associated with diesels and a dpf issue, Are petrol engines now fitted with an egr system?

[@tomthompson7400]

but without before and after pics it is of course just pure snake oil in a tin. if it actually did shift carbon , wouldnt it just block the cat at the best and the rings / valves at worst ,,,, sticking valves the guy talks about too ,,, really , you would be picking them out of the pistons if that was the case .....