The engine speed at idle speed either decreases or increases (the warning lamp for a malfunction of the engine management system may light up, see above)
1. Leakage of the inlet pipeline. Check, replace intake manifold seals and defective parts (see «Power system - check»).
2. Faulty crankcase ventilation system. Check emission control systems, replace defective parts.
3. Faulty absolute pressure and air temperature sensor. Run diagnostics on the engine management system (see «Engine management system»). Replace defective element.
4. Insufficient pressure in the fuel rail. Check the pressure in the fuel supply system (see «Power system - check of technical condition»), replace defective parts.
5. Worn timing belt and/or belt tensioner. Check the technical condition of the engine (see «Engine - condition check») and replace defective parts.
Misfire (engine interruptions) idle and/or under load (the warning lamp for a malfunction of the engine management system may light up, see above)
1. Faulty spark plugs. Replace spark plugs (see «Spark plugs - replacement»).
2. Leakage of the inlet pipeline. Replace intake manifold seals and defective parts (see «Power system - check of technical condition»).
3. Clogged fuel filter. Replace fuel module (see «Fuel module - removal and installation»).
4. Defective fuel injectors. Check and replace faulty fuel injectors (see «Nozzles - check and replacement»).
5. Insufficient compression in the engine cylinders. Check the technical condition of the engine (see «Engine - condition check»). Repair the engine by replacing worn and defective parts.
6. Faulty ignition coil. Check and replace the ignition coil (see «Ignition coil - check and replacement»).