Engine Misfire and Fault Code P105D or P105C
In 2016 Chrysler released a version of the Penestart Engine labeled the Upgraded design, the new features included a liquid cooled EGR, Electronic Stop Start, a 20 degree increase in VCT phase angle and specific to this post the VVL or Variable Valve Lift System.
The VVL was designed to reduce intake stroke pumping losses and increase efficiency under light load conditions. The reduction in incoming air mass into the cylinder was now a controllable function by way of the valve train. The system is only for the intake camshaft and there are four control solenoids, two in the front and two in the rear. The front VVL solenoids are in charge of 1 cylinder where as the rear VVL solenoids are in command of two cylinders per.
The system has two positions or steps, high lift, which is the default, and low lift. The high lift lobe is narrow and sandwiched in between two low lift camshaft lobes forming a hydraulic finger follower design which is regulated by engine oil pressure. Depending on the command, the inner portion of the follower known as a slider will either lock in place for high lift or unlatch from the follower and move independently for low lift. The follower is connected to a spring loaded locking pin which is pushed back by engine oil pressure which should be at minium 20 psi per Chrysler service information. As with any component dependent on hydraulic pressure there are known failure points and while there are 16 codes specific to solenoid failure we're going to focus on the system performance fault codes P105C and P105D.
P105D
The vehicle PCM runs a monitor to check for the position of the low and high lift valve positions and as part of the criteria other data or enabling criteria must be cross referenced. In the event that a vehicle does have fault code P105D the intake valves may be stuck in a high position, which is the system default. Conversely the P105C fault code indicates the intake valves may be stick in a low level position.
The testing process for a system fault such as P105C or P105D is to run an intrusive VVL service routine, which is a three part test checking for the ability to switch from high lift to low lift.
Common Failure Points of VVL System
- Spring loaded pin failure creating a stuck condition.
- Failure of the lost motion spring which may cause the slider to slap
- Solenoid failure
- Solenoid O-ring failure resulting in an engine oil leak
- Low engine oil pressure, debris in the engine oil due to extended service intervals
- Mechanical Rocker Arm failure.
Symptoms of a VVL failure
A single low lift valve failure may cause an intermittent misfire which is felt more at higher speeds. A failure of mulitple VVL solenoids or a systemic failure will create a misfire at idle and the vehicle will limit engine speed to approximately 3,000 RPM.
If you own a Chrysler product including a newer model Jeep, Pacifica or Challenger give us a call today to schedule an inspection of your vehicle's VVL system.