Chrysler engines were equipped with VVT (for variable valve timing) starting in 2007.
In the sections below, we describe the basic features of several versions of VVT used in different Chrysler engines. Keep in mind that, as with many drivetrain components, systems and functions, VVT is increasingly integrated in the engine management systems. When you are fault finding and troubleshooting the engine, starts with the use of factory diagnostic system or equivalent scan tool. Also, as in all diagnostic situations, verify that the basics -- engine mechanical condition, fuel supply and electrical power supply -- are within the correct range before attempting to diagnose complex electronic or mechanical systems.
Variable valve timing (also often referred to as variable camshaft timing) improves the flexibility and efficiency of an engine, allowing a manufacturer to meet environmental goals and fuel efficiency standards while providing high performance. By advancing intake camshaft timing at medium engine speeds, pumping losses are reduced and engine efficiency increased. This feature also acts as an internal EGR system and reduces NOx emissions, eliminating the need for additional external EGR pluming. Similarly, advancing exhaust valve timing under certain conditions allows better cylinder filling and higher engine efficiency.
The technical term for the system used in Chrysler’s variable valve timing control is “hydraulic cam phasing”. The system continuously varies the camshaft target position based on the engine operating parameters. Based on these parameters the powertrain control module (PCM) calculates or models the optimum camshaft position. The camshaft angular position is varied by the oil control valve. The (VVT) solenoid pushes on a plunger (spring loaded spool valve) in the center of the oil control valve (OCV) which directs oil pressure to the hydraulic actuator (phaser) on the camshaft sprocket to change the camshaft position relative to the crankshaft position. The (VVT) solenoid, acting on the oil control valve (OCV) and (phaser) is controlled by the (PCM), and the camshaft sensor (CMP) is used to monitor the position of the camshafts.
For 2016, Pentastar V-6 engines were additionally equipped with a two-stage valve lift capability. At moderate speeds the valves operate at low lift, but when the driver calls for more power, the high valve-lift phase is activated. The system, controlled by the PCM, uses engine oil powered solenoid valves to lock or unlock the cam follower in two different positions.
In V-8 models with the Hemi engine, VVT and variable valve lift are combined with Multi Displacement System (MDS) to achieve additional fuel efficiency. The MDS system turns off the fuel in four of the 8 cylinders when power is not needed. Using individual valve control, intake and exhaust valves on the four inactive cylinders are closed. Even though there is some loss of energy through additional compression, none is lost by pumping air through those cylinders.
Chrysler VVT common failure issues
The following common failures have been documented for current Chrysler VVT systems:
VVT solenoid failure:
- Dirty engine oil clogging the passageway from the solenoid to the VVT chain and gear.
- Dirty engine oil clogging the oil control solenoid.
Intake and exhaust cam phaser actuators internal part failures.
- Collapsed lifters causing rocker arms to fall off the valve springs and grinding down the intake and exhaust camshaft lobes.
- Rocker arms warp.
- Valve springs develop stress cracks.
- Spool valves do not move freely inward and return to flush position due to bad intake and exhaust oil control valves.
Late 2016 3.6 liter VVT engines misfire fault codes stored:
- P000A - Camshaft slow to respond
- P000C - Camshaft slow to respond
- P0300 – Multiple cylinder misfire
These fault codes are often caused by defective camshafts on bank 1 and 2. Replacement of the camshafts is necessary. This affects all engines produced from January 09, 2016 to March 06, 2016. Other production dates may also be affected.