When inspecting cylinder compression, the engine should be at room temperature, the throttle should be open, the spark plugs removed and the battery at full charge. The lowest reading cylinder should not be less than 70% of the highest and no cylinder reading should be less than 100 psi. Turn ignition key until engine cranks through four compression cycles per cylinder. Normal compression builds up quickly and evenly to specified compression on each cylinder. |
Chevrolet Cobalt Owners Manual. Electric Power Management
This vehicle has Electric Power Management (EPM),
an advanced control system. It estimates the battery's
temperature and state of charge and then adjusts the
voltage for best performance and extended life of the
battery.
When the battery's state of charge is low, the voltage
is raised slightly ...