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Direct Injection Walnut Carbon Cleaning

Many vehicles with direct injection engines suffer from an excessive carbon build up on the intake valves. The carbon build up can cause drivability issues such as stumbling, flat spots and lack of power, poor throttle response etc. In addition, carbon build-up on the intake valves is commonly associated with an inconsistent idle and in some cases, a direct injection engine will not idle at all when cold. In most cases, this will lead to a check engine light and failure to pass emissions.

Intake Valves with Carbon Build Up

Carbon build-up around intake valves in a direct injected engine is a sticky coating of oil and fuel constituents. Once formed, it continues to grow further coating the thickness of the deposits and has an extremely negative effect on engine performance. One manufacturer has cited a potential risk for pieces of this carbon to break off and burn holes in the structure of the catalytic converter. This is potentially very destructive and expensive.

Before walnut blasting

Direct Injected Engine Carbon Cleaning With Walnut Shell Blasting

Euro King Auto provides walnut shell cleaning of direct injection engines. This process safely removes the carbon build up and is significantly less expensive than removing cylinder heads and subsequently cleaning the valves. The process is conducted using an approved tool that blasts walnut shell particles directly on to the intake valves. The process removes all of the carbon build up and consistently returns good engine performance. To de-carbon inlet ports and valves generally takes less than a day although we prefer to have them overnight rather than rush the job and the results are excellent – throttle response and power return immediately.

After walnut blasting

Why Does Carbon Build-up On The Intake Valves?

Most of the very recent engine designs and technical enhancements have greatly reduced the issue of carbon buildup, but it has been a distinct and well-documented issue in most direct injection engines over the last few years.

There’s a lot of discussion as to why and not many straight answers. The bulk of the answer relates to what’s in the air passing through to the intake valves. This air also contains gases recycled from the exhaust and crankcase fumes recycled through an air oil separator. In a regular injection car, the fuel is vaporized ahead of the intake valves into this air mixture and drawn into the cylinders. The vaporizing of the fuel in the air likely grabs those rogue particles from the crankcase fumes and the exhaust gas and they pass into the cylinder to be burnt.

In a direct injection engine, the fuel is vaporized directly into the cylinder. This leaves the air containing the other particles to pass over the hot intake valves and into the cylinder untouched. It seems those particles from the crankcase and exhaust recycling collect on the hot intake valves rather than pass into the cylinder to be burnt. Once this happens, the problem gets worse every time the engine is run and the deposits get larger. Where porting and polishing the intake improves performance, the carbon build up on the intake valves and surrounding ports does the complete opposite. Eventually the engine is starved of available air and performance at all levels is significantly reduced.

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