I am working on a 2014 Cruze LS 1.8L NA I4with approximately 120K. The car idles erratically and the MIL/CES light is illuminated. My reader lists only one code: P0171 lean mixture detected. I noticed a whistling sound that I believed to be a vacuum leak. I checked the purge control solenoid and it is completely sealed with the power connector removed. I finally discovered the location of the leak. There is a small vertical slot on the right (passenger) side back of the plastic intake manifold assembly. This is to the right of the throttle body housing.
My big question is the leak the result of an internal defect in the plastic intake assembly or is this leak caused by the failure of the PCV valve in the valve/camshaft cover? I do not mind replacing parts, however, I prefer not wasting money on replacement parts that do not need to be replaced.
I have searched multiple sites and have not found these exact symptoms. PCV Valve diaphragm in the 1.8L is less common than with the 1.4L turbo.