How to Determine If a Car Needs Carbon Deposit Cleaning?
3 Answers
When the car experiences idle vibration, it indicates the need for carbon deposit cleaning. Here is the relevant information: 1. Carbon Deposit: Carbon deposit refers to a coking-like substance produced by unsaturated olefins and gums in fuel under high temperatures during engine operation. 2. Types of Carbon Deposits: There are valve and combustion chamber carbon deposits and intake pipe carbon deposits. Valve and combustion chamber carbon deposits occur because each time the cylinder operates, fuel is injected before ignition. When the engine is turned off, ignition is immediately cut off, but the fuel injected during this cycle cannot be recovered and adheres to the intake valve and combustion chamber walls. The fuel evaporates easily, but the wax and gums in the fuel remain. Over time, these substances accumulate and harden with repeated heating, forming carbon deposits. Intake pipe carbon deposits occur because the pistons in the engine do not operate synchronously. When the engine is turned off, some cylinders' intake valves do not close completely, causing unburned fuel to evaporate and oxidize continuously. This results in softer black carbon deposits in the intake pipe, especially behind the throttle valve.
After driving for so many years, the most noticeable issue I've encountered is a significant drop in the car's power. In the past, a light tap on the accelerator was enough to overtake, but now even pressing it hard results in a delayed response, as if something is holding it back. During cold starts, the engine shakes a couple of times, the tachometer needle isn't very steady, and the exhaust fumes are particularly strong right after ignition. On the highway, I've noticed an inexplicable increase in fuel consumption, requiring more frequent refueling. There was also a time when I heard a metallic knocking sound from the engine during acceleration, like small stones hitting the exhaust pipe—a distinct rattling noise. All these signs together pretty much point to carbon buildup clogging the fuel injectors or the throttle body. Nowadays, I regularly add some fuel system cleaner and intentionally rev the engine higher on the highway to clear out the carbon deposits, saving myself the hefty cost of dismantling the engine for cleaning.
When driving an older car, pay attention to three signs of carbon buildup: the throttle feels heavier during acceleration, and the RPM rises slowly; at idle while waiting at a red light, you may notice slight steering wheel vibrations and the tachometer needle fluctuating slightly; the engine is prone to stalling during the first cold start. These issues occur because carbon deposits accumulate on the piston tops and valves, affecting the air-fuel mixture. I make it a habit to inspect the spark plugs every 30,000 kilometers—if the electrodes appear blackened or oily, it indicates severe carbon buildup. Cars frequently driven on short trips are particularly prone to carbon deposits, as unburned fuel mixes into the engine oil. It's recommended to take a monthly highway drive at high RPMs to help flush out deposits. Don’t rely on those "no-disassembly" cleaning products—if the problem is severe, you’ll still need to remove the intake manifold and manually scrape off the deposits.
