Many modern vehicles powered by Gasoline Direct Injection (GDI) engines are showing up in Service Departments with mysterious complaints: high oil consumption, misfires and performance loss. These problems can put the diagnostic skills of even the best Technicians to the test.
Our customer was complaining of excessive fuel consumption in his V6 Kia Carnival. As we worked through our intensive list of possibilities that may cause this issue, (I am happy to email anyone this list should you like a copy) we came to the primary and secondary ignition integrity checks that are on our list.
The customers vehicle was a 2008 BMW 530D, which came to us with the check engine light illuminated and very low power output. We found the car very sluggish, almost like it had no boost pressure. The fault code reading showed a particulate filter blocked/low flow issue.
In order to reduce frictional drag, energy loss and increase fuel efficiency, gasoline direct injection (GDI) engines use thinner and lighter piston rings, called low-tension piston rings. Piston ring spring force in older port fuel injection (PFI) engines used to be as high as 30 psi. New PFI and GDI engines can have more than 60 percent reduction in sealing pressure on the cylinder walls.