Conduct regular inspections of hoses and clamps.
If necessary, replace the components of the crankcase ventilation system.
A clogged PCV hose can cause the following:
- idle instability;
- muting or low idle;
- oil leak;
- oil in the air filter;
- residue in the engine.
Leaking PCV hose can cause the following:
- idle instability;
- spontaneous engine stop;
- high idle speed.
Exhaust gas recirculation valve
The exhaust gas recirculation system is used on engines equipped with automatic transmissions to reduce NOx emissions (nitrogen oxides), caused by high combustion temperature.
The EGR valve is controlled by the engine control unit (ECM). The EGR valve allows a small amount of exhaust gases into the intake manifold to lower combustion temperatures. The amount of exhaust gas processed is controlled by vacuum differentials and exhaust gas back pressure.
When an excessive amount of exhaust gases is supplied to the cylinders, the fuel will not ignite. For this reason, the valve passes a very small amount of gas, especially at idle.
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 results in poor ignition, resulting in engine instability or stalling. Too much EGR flow at idle, cruise control, or a cold engine may cause the following conditions:
- engine stalls after cold start;
- the engine stops idling after braking;
- while driving using the cruise control system, the car jerks;
- unstable idle.
The EGR valve is open all the time and the engine may not idle. No or weak EGR flow allows the combustion temperature to be exceeded 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.