So remember last week. We were working on this 2017 Silverado that had rough starting and misfires. It had two issues, the first was 3 failed fuel injectors which we showed you that process last week.
The second issue was there is excess carbon buildup on the inlet valves. The inlet valves or intake valves are how clean air is supposed to enter the engine when it’s running.
This engine and many other newer vehicles utilize a system known as Gasoline Direct Injection or GDI for short. This means the fuel injector sprays fuel directly into the cylinder. This is to help with fuel economy, emissions and power.
With older engines, they utilized a system known as Port Fuel Injection where the fuel injector sprays ahead of the intake valve.
With Port Fuel systems, the gasoline at the back of the intake valves naturally cleans them and it would be very rare to have carbon buildup on them. (See picture below).
With 90% of GDI engines, there is no fuel at the back of the intake valves, so carbon is very prone to build and excessively to where it will cause hard to diagnose misfires, rough running and hard starting engines.
Preventing carbon buildup is difficult in a GDI engine. The main things you can do are:
1. Have your oil and filter changed at 5,000 miles tops and using a “very high quality” oil and filter. (Yes, cheap oil changes and extended oil changes are going to cause problems in the long run on these engines). Our facility only utilizes high quality, manufacturer grade oils and high quality oil filters.
2. Use what’s called Top Tier detergent gasoline (link below). Yes there are different qualities of fuel being sold all over Omaha. The detergents in gasoline can actually help prevent carbon buildup and injector problems.
So what do we do when carbon buildup is excessive and causing problems??
This vehicle went through a 2 step process to remove the heavy carbon. We didn’t have to perform any major repairs either to fix the issue, which is really cool for the client.
Step 1 is a chemical treatment to soften the carbon and get some of the larger chunks off, step 2 is a walnut blast procedure where we utilize ground up walnut shells, pressurized air and a vacuum. The process does take some time, but look how great the valves turned out. Guess what, the engine ran flawless when we were done.
As more and more GDI engines hit the road and start to age, we are going to start seeing these problems more frequently, but we don’t want it to happen to you!
Cool stuff and thanks for reading this long post today!