The 2.0 Liter (122 cu. in.) in-line four cylinder engine is a double over head camshaft with mechanical lash buckets and four valves per cylinder design. This engine is NOT free-wheeling; meaning that the pistons will contact the valves in the event of a timing chain failure.
The cylinders are numbered from front of the engine to the rear. The firing order is 1-3-4-2.
The engine serial number is located on the rear of the cylinder block. The serial number contains engine build date information.
ENGINE DIAGNOSIS - INTRODUCTION
Engine diagnosis is helpful in determining the causes of malfunctions not detected and remedied by routine maintenance.
These malfunctions may be classified as either mechanical (e.g, a strange noise), or performance (e.g, engine idles rough and stalls).
Refer to the ENGINE DIAGNOSIS - MECHANICAL and ENGINE DIAGNOSIS - PERFORMANCE for possible causes and corrections of malfunctions.
For fuel system diagnosis, see FUEL SYSTEM .
Additional tests and diagnostic procedures may be necessary for specific engine malfunctions that cannot be isolated with the Service Diagnosis charts. Information concerning additional tests and diagnosis is provided within the following
- Cylinder Compression Pressure Test: Refer to «CYLINDER COMPRESSION PRESSURE TEST»(ref-304329-S30513242942008110700000) .
- Cylinder Combustion Pressure Leakage Test: Refer to «CYLINDER COMBUSTION PRESSURE LEAKAGE TEST»(ref-304329-S27594441902008110700000) .
- Engine Cylinder Head Gasket Failure Diagnosis: Refer to «CYLINDER HEAD GASKET»(ref-304329-S33931184912008110700000) .
- Intake Manifold Leakage Diagnosis: Refer to «MANIFOLD-INTAKE»(ref-304329-S24986665512008110700000)
- Mechanical Valve Tappet Noise Diagnosis: Refer to «HYDRAULIC LASH ADJUSTER NOISE DIAGNOSIS»(ref-304329-S39328087602008110700000)
- Engine Oil Leak Inspection: Refer to «ENGINE OIL LEAK INSPECTION»(ref-304329-S18033314782008110700000)
DESCRIPTION
Both camshafts have five bearing journal surfaces and two cam lobes per cylinder. The two front journals are larger to allow for feeding oil to the variable valve timing (VVT) camshaft phasers. Flanges on the third smaller journal control camshaft end play. At the rear of each camshaft is an integral cam sensor target.
The world engine is equipped with Variable Valve Timing (VVT). This system advances and/or retards intake and/or exhaust camshaft timing to improve engine performance, mid-range torque, idle quality, fuel economy, and reduce emissions. The camshaft sprockets are integrated with the VVT assemblies and are serviced as an assembly. VVT assemblies are sometimes referred to as camshaft phasers.
OPERATION
The Variable Valve Timing (VVT) assemblies are actuated with engine oil pressure. The oil flow to the VVT assemblies are controlled by two Oil Control Valves (OCV). There is an OCV and Camshaft Position Sensor (CMP) for each camshaft. The OCV's consist of a Pulse Width Modulated (PWM) solenoid and a spool valve. The PCM actuates the OCV to control oil flow through the spool valve into the VVT assemblies. The VVT assembly consists of a rotor, stator, and sprocket. The stator is connected to the timing chain through the sprocket. The rotor is connected to the camshaft. Oil flow in to the VVT assembly rotates the rotor with respect to the stator, thus rotating the camshaft with respect to the timing chain. Thus, the VVT assemblies change valve timing by changing the relationship between the camshaft and the timing chain. An integral oil pressure activated pin is used to lock base camshaft timing for engine start up. Oil pressure releases the pin and allows the PCM to control cam timing once the engine is running. An infinitely variable valve timing position can be achieved within the limits of the hardware. The CMP monitors the position of the camshaft with respect to the crankshaft and provides feedback to the PCM.