Comments by "John Cooper" (@johncooper4637) on "A MUST for Gasoline Direct Injection! Intake Valve u0026 Injector Maintenance!" video.

  1. Watching "I Do Cars" convinced me that direct injection engines need this service. I made sure my Jeep did not have direct injection. I also clean out the carbon by driving, legally, on Texas highways at 85 MPH.
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