Diagnose and fix Volkswagen GTI Misfire
If you have a late model Volkswagen GTI misfire issue, chances are you’ve got carbon buildup on the intake valves. The misfire usually affects just one or two cylinders. However, here’s the process of diagnosing the problem.
Start your diagnosis of Volkswagen GTI Misfire by checking the spark plugs
You have to remove the spark plugs anyway to perform a compression test, so start there. Compare the visual condition of the plugs, looking for signs of soot or oil buildup. Also, check spark plug gap.
Perform a compression test on all cylinders
Attach a compression gauge and record the pressures of each cylinder. A low reading on one or two cylinders is usually an indication of carbon buildup on the intake valves.
Swap ignition coils
If all the compression readings are the same, that can indicate a weak ignition coil. Swap a coil for another cylinder and see if the misfire moves to the other cylinder
If you have low compression in one or two cylinders
Late model Volkswagen GTI misfires are a known problem and its
often caused by carbon buildup on the intake valves. No gasoline tank additive will fix this because the fuel doesn’t contact the valves. Instead, since it’s a gasoline direct injection engine, the fuel is injected directly into the cylinder. So you have to introduce the cleaner into the intake.
Perform an upper intake valve cleaning
Purchase a can of CRC Intake Valve Cleaner. Then follow the instruction in this video
If you still have a Volkswagen GTI Misfire after cleaning
Some shops are reporting broken valve springs. Diagnosing and fixing a broken valve spring requires removing the valve cover and measuring and visually inspecting each valve. It also requires removal of the camshaft. The part itself isn’t that expensive, but there’s some labor involved. If you do this yourself, you’ll need a very good torque wrench, valve spring compressor, and air chuck to fit in the spark plug hole.
©, 2019 Rick Muscoplat
Posted on by Rick Muscoplat