How to Clean Carbon Deposits in the Engine?

[DelAlexander]

Methods for cleaning carbon deposits in the engine: 1. Connect a carbon deposit cleaner to the engine's fuel injector, using the cleaner to soften the carbon deposits inside the engine so they can be burned and expelled; 2. Disassemble the engine's intake manifold for cleaning, then scrape off stubborn carbon deposits, and reassemble the engine after cleaning; 3. Drive more on long trips or highways, as the vehicle in a warmed-up state hardly produces carbon deposit buildup, and the high-speed operation of the engine can expel some carbon deposits. Carbon deposits are a coking-like substance produced during the engine's operation from unsaturated olefins and gums in the fuel under high temperatures. They have oil-absorbing properties, causing incompletely burned gasoline to turn into more carbon deposits. Carbon deposits reduce engine power, increase fuel consumption, and in severe cases, can cause engine knocking, acceleration noises, and other issues. They can also damage pistons and crankshafts, potentially leading to engine oil burning and requiring major repairs.

[DianaMarie]

Last week I just decarbonized my old car, to be honest it depends on the severity. If it's not serious, the easiest way is to add fuel additive and drive on the highway—pour a bottle of dedicated cleaner after filling up the tank, then drive in S mode for half an hour keeping the RPM above 3000. If you still notice lack of power during acceleration and pungent exhaust fumes, it's likely the piston rings and intake ports are clogged. The most reliable method is to go to a repair shop and use walnut shell blasting equipment—physical scouring is much more effective than chemical solutions. Remember, for direct injection engines, focus on cleaning the back of the intake valves, while traditional port injection engines require attention to the fuel injector locations. Never trust roadside stalls that suggest adding cleaner to the engine oil—it damages the engine!

[BlakelyLynn]

Engine carbon deposits mainly accumulate in four locations, each requiring completely different cleaning methods. Throttle body carbon can be cleaned by disassembling and wiping with carburetor cleaner; intake manifold deposits require specialized foam spray followed by idling; combustion chamber carbon needs hydrogen-oxygen decarbonization machine for dissolution; clogged fuel injectors must undergo ultrasonic cleaning. I usually advise car owners to budget 800-1200 for walnut shell blasting + hydrogen-oxygen decarbonization combo, which delivers the most comprehensive results. Special reminder: small displacement engines below 1.5T should avoid foam cleaners as residue can clog catalytic converters. For routine maintenance, add fuel system cleaner every 2,000 km and develop the habit of idling for 1 minute after cold starts - this can reduce carbon buildup by 60%.

[LeHannah]

Comparison of Three Main Carbon Deposit Cleaning Methods Based on Personal Testing: Fuel additives are the most cost-effective but offer limited effectiveness, suitable for new cars under 30,000 km; intake system cleaning via IV drip costs around 400 RMB with moderate results, effectively cleaning intake pipes and throttle bodies; hydrogen-oxygen decarbonization machines cost 700 RMB but deliver impressive results, especially for combustion chamber deposits. The most severe carbon buildup case I've seen was a ride-hailing driver with a 3mm-thick carbon layer on piston tops, directly causing cylinder pressure loss. Such cases require engine disassembly for manual scraping. For city commuter cars, an intake system cleaning every 30,000 km is recommended, especially for vehicles primarily used for short trips. After cleaning, you'll noticeably feel a lighter throttle response and crisper cold starts.

[Ivan]

DIY Carbon Cleaning Tips: Buy a bottle of Liqui Moly Engine Cleaner and add it to a full tank of 92-octane gasoline, then drive until the fuel light comes on. Disconnect the intake pipe and spray 3M specialized foam onto the throttle body, wait until the foam turns black, then start the engine and rev it. Use a borescope to inspect the cylinders; if stubborn carbon deposits remain, visit a shop with BG equipment. Note that direct injection engines cannot clean the intake valves with chemicals—they must be disassembled for cleaning. After cleaning, perform an ECU reset; otherwise, the idle may fluctuate. Older cars might trigger a fault light after cleaning, but it will disappear after driving a few dozen kilometers. Don’t trust folk remedies like using diesel to clean the engine—it can damage the car! Limit cleaning frequency to no more than once every 20,000 km, as excessive cleaning can harm the cylinder walls.

[LaReagan]

Prevention is better than cure! I insist on adding BASF original additive with every tank of fuel, and after 100,000 kilometers, the disassembled engine looks like new. The core of preventing carbon buildup lies in three points: frequent air filter replacement (must change every 20,000 km), never exceed six months for oil changes, and mandatory monthly 30-km highway driving. For vehicles already with carbon deposits, don't rush into cleaning—first measure cylinder compression. Only proceed if below 8 bar, otherwise it's wasted money. Special reminder: cars with start-stop functions are more prone to carbon buildup, recommend disabling this feature. After cleaning, remember to reset ECU adaptation values, otherwise fuel consumption will spike. The package cleaning promoted by repair shops is completely unnecessary—just check the blackening level inside the exhaust pipe to gauge carbon buildup.