VVT solenoid common fault
1. VVT electronic valve common fault
Most of the faulty parts of the VVT system are oil-controlled solenoid valves, and the faults of the oil-controlled solenoid valves are almost all stuck by the moving spool valve .
2.the difficulty range of starting difficult (engine rotation is normal)
Spark plug, ignition coil failure; high voltage line leakage, wire connection loose or open.
2.2 oil circuit failure
The fuel pipe (including the hose) is dirty or clogged, and the fuel pump is faulty (check the fuel pressure).
2.3 electronic control part
Electronic throttle body assembly failure or APP sensor failure, ECT sensor or MAF sensor failure, ECM failure, camshaft position control system failure.
2.4 mechanical parts
Low cylinder pressure (spark plug tightening or gasket failure); pressure leak on the seat, stem sticking, insufficient valve spring force or damage; cylinder head gasket leakage, piston ring viscous or damaged, piston, ring or cylinder Wear; PCV valve failure, air intake from the intake manifold pad or throttle body pad.
3.the engine idling instability range (the engine has no idle speed)
Circuit failure spark plug failure, high voltage line leakage or high voltage line disconnection, point coil with igniter failure.
Fuel pressure is out of specification, fuel injector failure, evaporative emission control system failure.
Electronic control part failure
Poor sensor performance, electronic throttle body assembly failure (excessive carbon deposits, dirty, etc.), sensor failure, electrical load component failure (headlights, blowers and post-defrost), idle air control faults, generator and line faults, )system error
Intake manifold, throttle valve body or cylinder head gasket leakage Evaporative emission control system failure, engine overheating, low cylinder pressure, vacuum hose connection loose or open, valve failure (some models need to consider EGR valve closure is not strict).
4.Fourth, the oil control solenoid valve failure causes the difficulty of starting and the cause of unstable idle speed
When the engine is started and stopped, the position of the oil control solenoid valve should be at the maximum delay (in order to prevent the exhausted gas from flowing back to the intake manifold, the overlap of the valve opening should be shortened to improve the starting ability).
When the engine is idling, the position of the oil control solenoid valve should also be at the maximum delay (to prevent the exhausted gas from flowing back to the intake manifold, the overlap of the valve opening should be shortened to stabilize the engine idle speed).
If the foreign matter (metal particles, sludge, etc.) in the oil path enters the oil control solenoid valve, the moving slide valve is stuck in the advanced position. In this case, the vehicle is started, and the exhaust gas is reversed, and the intake air amount is insufficient, which may cause difficulty in starting or idling instability.
5. Failure of oil control solenoid valve causes difficulty in starting and unstable operation at idle speed
When it can't start, you can step on the throttle and basically start the vehicle. It is generally difficult to start without stepping on the throttle. The idling jitter is very large after starting.
You can knock the shock oil control valve on the car (slightly stuck can solve).
Disassembly check cleaning maintenance.
Replace the oil control solenoid valve (the resistance check does not match and the fault cannot be eliminated after cleaning)
Note: VVT solenoid manufacturer, VVT solenoid supplier, oil control valve manufacturer, oil control valve supplier, cam phaser manufacturer, cam phaser supplier.