|
The pics of those valves looks pretty good.
I had a BMW 135i which has DI, and has the problem of carbon buildup on the intake valves. My car started misfiring, and the dealership had to use a walnut shell type of sandblasting to clean the intake ports and valves. They were REALLY really clogged up with carbon.
The reason is that all DI engines still have EGR (exhaust gas recirculation) systems, where the engine crankcase blow-by is run back through the intake and reburned. Normally on a port injected engine, the gas flowing through the ports and over the valves effectively cleans these parts.
On Direct injection engines, only air, and the oily smoke from the EGR flows over the valves and ports, which are hot, and this smokey oil sticks to the ports and valves and builds up over time.
Our cars have both port, and direct injection, so I don't see us having this issue, but you can eliminate the possibilty of it happening by installing an oil catch can, also known as an air/oil separator.
These pull the oil out of the EGR blow-by, and send basically only air back through the engine. Some OCC's then run the captured oil back into the engine, others catch the oil and need to be emptied periodically,.
Oil catch cans/air-oil separators are relatively cheap and easy to install too, they are a good mod IMO.
|