Perform regular inspections of hoses and clamps.
If necessary, replace components of the crankcase ventilation system.
A clogged PCV hose can cause the following:
- idle instability;
- stalling or low idle;
- oil leak;
- oil in air filter;
- sediment in the engine.
A leaking PCV hose can cause the following:
- idle instability;
- engine stall;
- high idle speed.
Exhaust gas recirculation valve
The exhaust gas recirculation system is used on engines equipped with automatic transmission to reduce NOx emissions (nitrogen oxides), caused by high combustion temperatures.
The EGR valve is controlled by the engine control module (ECM). The EGR valve allows a small amount of exhaust gas to pass through the intake manifold to reduce combustion temperatures. The amount of exhaust gas recycled is controlled by vacuum differences and exhaust back pressure.
If too much exhaust gas is supplied to the cylinders, the fuel will not ignite. For this reason, the valve allows very little gas to pass through, especially at idle speed.
The EGR valve normally opens under the following conditions:
- the engine is warm and running;
- excess idle speed.
Result of incorrect operation
Too much EGR flow will weaken the ignition, which will cause the engine to run rough or stall. If the EGR flow is too high at idle, when driving with cruise control, or when the engine is cold, the following conditions may occur:
- engine stalls after cold start;
- engine stalls at idle after braking;
- when driving with cruise control the car runs jerkily;
- unstable idle speed.
The EGR valve is open all the time, but the engine may not idle. No or low EGR flow allows combustion temperatures to rise during acceleration or high load conditions. This phenomenon can lead to the following consequences:
- detonation of fuel in cylinders;
- engine overheating;
- excess of harmful emissions in exhaust gases.