Even if that flange was leaking slightly it would make no difference with the engine running - the EGR valve is still shut at idle and the tiny extra air ingested when the system operates would make no difference. IF the miss is in a single cylinder, rather than random missing, it's doubtful that a small/medium vacuum leak would cause that. Andrew Markel explains how a gasket that comes in contact with crankcase vapors can cause an oil leak, and how you can test pressure and vacuum with the righ Also, make sure there are no loose or broken wires before assuming this as a possible cause. 8. Burned exhaust valves. These can be a result of a rich fuel mixture or oil contamination from internal engine parts. If your car only has the P0420 trouble code, then you’re most likely looking at leaking/bad valve seals. Your oil burning is probably causing most the smoke. An increase in compression wet vs. dry indicates worn rings. as for cylinder #2, if could be a variety of things. Possibly a slightly burned valve (although burned valves usually tend to cause a more dramatic compression loss). . Some of the small failures include air leaks from torn gaskets, stretched clamps, ripped couplers, which can cause inaccurate readings to the pressure and temperature sensors, electrical faults of the sensors and EGR valve, and an increase in soot. This increase can not only damage the EGR system, but the turbocharger as well. In some cases, PCV systems can also have an oil/vapor or oil/water separator. Aside from the PCV valve, the system’s connecting hoses can get clogged with sludge. Once the system gets pressurized, engine oil can seep into the intake tube and enter the throttle body. Worn Piston Rings A PCV valve leak can cause the air-fuel mixture to run too lean, and this will cause a rough idle. PCV valve. Proper periodic servicing of the PCV valve will prevent this situation from occurring. The fix is to service the valve regularly and make sure that it is clean and fully operational. EGR valve stuck in an open position creates a vacuum leak that causes inefficient combustion. A valve that’s stuck in a closed position increases nitrogen oxide emissions, which disrupt engine timing, leading to engine knock. Three EGR Valve Faults: There are only 3 types of bad EGR valves, and each of them shows different symptoms. The EGR Jul 2, 2012. #14. an evap purge valve going bad is when they leak and let fuel vapor from the tank into the manifold and it causes a lean condition when not expected. they generally don't stick completely open where it's a vacuum leak and you feel it. It happens at random time and generally throws a lean condition on one or both cylinder banks

can a bad egr valve cause oil leak