What Causes Unstable Idle in a Camry?
1 Answers
The reasons for unstable idle in a Camry may include severe engine carbon buildup, ignition system issues, aging engine components, leaks in the intake manifold or various valves, and excessive dirt accumulation in the throttle body and intake passages. The details are as follows: Severe engine carbon buildup: The most common cause of car shaking is a dirty throttle body or excessive carbon buildup in the fuel injectors. When there is too much carbon inside the engine, the gasoline sprayed by the cold-start injector is largely absorbed by the carbon deposits, resulting in an overly lean air-fuel mixture during cold starts and making it difficult to start. Ignition system issues: Check the condition of the spark plugs, high-voltage wires, and ignition coils. Poor performance of the ignition system or weak sparking from the spark plugs can also lead to such faults. Unstable fuel pressure: If you have already cleaned the engine carbon, cleaned the throttle body, replaced the oil seals and spark plugs, but still notice shaking at idle, it could be due to abnormal fuel pump pressure or incorrect readings and poor performance of the intake pressure sensor, which can cause the car to shake. Aging engine components: Car shaking can also be related to worn engine mounts. Engine mounts are essentially the shock absorbers for the engine, responsible for absorbing minor vibrations during operation. If the engine mounts are faulty, these vibrations will be transmitted to the steering wheel and cabin, causing shaking at idle. Leaks in the intake manifold or various valves: When unwanted air, fuel vapor, or exhaust gases enter the intake manifold, the air-fuel mixture becomes too rich or too lean, leading to abnormal combustion. If the leak affects only certain cylinders, the engine will shake more violently, especially during cold idle. Excessive dirt accumulation in the throttle body and intake passages: Too much carbon and dirt in the throttle body and surrounding intake passages changes the cross-sectional area of the air passages, preventing the control unit from precisely regulating the idle air intake. This results in an overly rich or lean mixture and abnormal combustion.
