What are the symptoms of excessive carbon deposits in the idle motor?

2 Answers
LeAndres
07/29/25 4:09pm
Symptoms of excessive carbon deposits in the idle motor include: unstable power output during acceleration or overtaking, accompanied by dull abnormal noises from the engine; difficulty in starting the engine when cold, with continuously increasing fuel consumption; pungent exhaust fumes and a large amount of sludge and colloidal substances inside the exhaust pipe. Below is an introduction related to the idle motor: 1. Introduction: The idle motor is a component that controls the idle speed of a motor vehicle. When the engine runs without load, it is referred to as idling. 2. Function: The idle motor is primarily responsible for managing the vehicle's idle speed, aiming to adjust the idle based on the engine load during idling. The idle stepper motor is mounted on the throttle body and is used by the engine control unit to regulate engine idle speed. When the engine speed deviates from idle, the throttle valve adjusts to control the amount of air entering the intake manifold, operated mechanically by the accelerator pedal cable. The throttle has a bypass air passage that supplies air during engine idling (when the throttle is closed). The pivot of the automatic idle motor extends into the bypass air passage, regulating the air flow through it. The engine control unit uses input signals from various sensors to move the pivot of the automatic idle motor in and out of the bypass air passage, thereby adjusting the engine idle speed. The automatic idle motor begins operation when the ignition key is turned to the 'on' position. This switch signal is input to the ECU to determine whether the engine is in idle mode. Additionally, the motor's current position is fed back to the ECU by the motor position sensor.
Was this review help?
15
2
Share
MacJoel
08/15/25 4:34am
My car's idle speed motor has excessive carbon buildup, and the symptoms are particularly noticeable, causing frequent annoyances while driving. For instance, the engine RPM fluctuates erratically at idle, unstable like dancing, and the car shakes violently, especially when stopping at traffic lights—it feels like an earthquake. Cold starts are especially difficult; in winter, it takes several attempts to get the engine running. Sometimes, it even stalls directly at idle, leaving me on edge. Fuel consumption has also skyrocketed, burning much more gas than usual, and the tank empties quickly after refueling. These issues occur because carbon deposits block the motor's position, disrupting airflow. Neglecting regular maintenance often leads to this. I recommend periodic inspection and cleaning to prevent minor issues from escalating. If similar problems arise, take the car to a repair shop immediately to avoid breakdowns on the road.
Was this review help?
6
0
Share
Expand All
More Forum Discussions

What are the reasons for the inability to raise or lower the windows on all four doors of an old Passat B5?

The inability to raise or lower the windows on all four doors of an old Passat B5 may be due to a fuse failure. Below is an introduction related to the Volkswagen Passat: Reasons for car window malfunctions: Loose screws in the window regulator, which can cause the regulator to jam. This situation may arise from deformed or damaged window channels, loose fixing screws of the regulator, misaligned guide rails, or a damaged window regulator. Other possible causes include a detached ground wire from the combination switch, a disconnected main power wire, poor contact or damage to the relay, or the relay not being closed. Solutions for car window malfunctions: Perform an initialization procedure. The general method for initialization is to turn on the ignition switch, pull and hold the switch to raise the window until it reaches the top, then continue holding for more than 3 seconds. Release the switch and immediately press and hold it again to lower the window to the bottom, waiting for more than 3 seconds. Then, pull and hold the switch to raise the window to the top once more, continuing to hold for more than 3 seconds. Once initialization is complete, the window should regain its original functionality. If this general method does not work, refer to the owner's manual or consult a service station. If the correct method still fails to initialize the window, it is likely that there are issues with the left front door lock, body control module, door lock position switch, lock cylinder switch, or other components. In such cases, it is recommended to visit a service station for inspection and repair.
14
2
Share

How many kilometers can an Audi run when it indicates insufficient oil?

Audi can still run about 100 kilometers after the oil light comes on. The following is its related introduction: Hazards: When the oil yellow light alarms, it means that the oil level has reached the lower limit. Driving with insufficient oil will cause the engine to overheat, increase wear, and seriously affect the working condition of the engine. It can be used for short-term emergency driving. However, it is not recommended to drive at high speed, otherwise the engine may not be lubricated well, causing serious damage to the engine. Oil alarm precautions: When the car oil system pressure is idling, about 1.0 is enough. When accelerating, the general pressure should be 4.5kg, and the gasoline system pressure for carburetor is 1.5kg. For fuel injection vehicles, according to the model, the pressure for low-end cars is generally 2.5-3.0. The general pressure does not exceed 3.5, and the minimum pressure should not be lower than 2.5.
20
1
Share

What Causes the ABS Red Light to Illuminate?

ABS light illumination can occur in various states, each with different fault causes and corresponding solutions, as detailed below: State 1: ABS warning light remains constantly lit (most common). Cause 1: The ABS wheel speed sensor's sensing area is covered by contaminants such as mud or dirt, affecting its ability to detect vehicle speed signals. This prevents the ABS control module from determining vehicle speed or calculating wheel slip rates, thereby disabling its ability to issue appropriate commands for brake adjustment. Solution: Clean the dirt from the wheel speed sensor and adjust the gap between the sensor and the tone ring to restore normal function. Cause 2: Poor signal transmission due to loose system wiring connections or faulty ABS relay contacts. Solution: Inspect wiring connections and re-secure any loose connections. State 2: ABS warning light intermittently illuminates but turns off during acceleration. Cause: When multiple electrical components are in use, battery voltage drops below 10.5V. As engine speed increases, voltage rises and the ABS light extinguishes. This may also indicate insufficient power supply voltage to the ABS system due to poor terminal contact or grounding issues. Solution: Check battery specific gravity; inspect charging system; examine power supply components (e.g., voltage relay or poor power connections). State 3: ABS warning light remains illuminated after engine start until engine IFF (Ignition Off) occurs. Cause: Poor grounding connection of ABS hydraulic valve body; faulty wiring connections at ABS hydraulic valve body; ABS control module malfunction. Solution: Loosen and retighten hydraulic valve body ground screw, cleaning contact surfaces if necessary; check for enlarged connector gaps; replace ABS or ABS/ASR control module. State 4: ABS warning light illuminates during high-speed driving. Cause: ABS control module detects excessive speed difference between rear and front wheels; incorrect tire or wheel rim specifications. Solution: Verify proper tire and wheel rim specifications as indicated on vehicle specifications or fuel filler cap label. State 5: ABS warning light flashes intermittently. Cause: Improper brake light switch adjustment; internal contact failure in brake lights. Solution: With engine running, depress brake pedal and manually push brake switch linkage downward to its limit, then release pedal to complete self-calibration; replace brake light switch if necessary. When the ABS warning light is illuminated, continued driving is not recommended. An active ABS light indicates malfunction in the anti-lock braking system. During emergency braking, wheel lock-up may occur, potentially causing loss of vehicle control and skidding, preventing the driver from decelerating or adjusting vehicle trajectory - presenting significant safety risks.
8
5
Share

What is the sequence of the C2 automatic transmission Subject 2 driving test?

The sequence of the C2 Subject 2 test items is: reverse parking, parallel parking, curve driving, and right-angle turning. Compared to the C1 manual transmission test, it excludes the hill start. According to Article 25 of the "Regulations on the Application and Use of Motor Vehicle Driving Licenses" (Ministry of Public Security Order No. 123), starting from June 1, 2021, the C2 and C5 Subject 2 tests no longer assess hill start and stopping. Reverse parking is considered one of the more challenging items in the Subject 2 test, which is why many test centers place it as the first item. The key to reverse parking lies in mastering three points: the steering wheel full-lock point, the 30 cm correction point, and the parking point inside the bay. Drivers must follow the prescribed route and sequence. The vehicle must be parked inside the bay without crossing the lines. Parallel parking focuses on aligning the front line of the parking space with the rear wheel, spotting the rear corner in the side mirror, and maintaining the correct distance between the wheel and the left dashed line. There's no need to straighten the wheels after parking, but don’t forget to use the turn signal when exiting. After parking, the vehicle body must not cross the lines, and the tires must not touch or press the lane boundary lines during movement. Curve driving, commonly referred to as the S-curve, is manageable for many students with good driving sense, indicating its relatively low difficulty. However, some students misjudge the line positions during the actual test, leading to immediate failure by crossing the lines. The key to the S-curve is observing the position of the hood marker points relative to the boundary lines. The wheels must not press the road edge lines. Right-angle turning is arguably the easiest, essentially a simplified version of the exit part in reverse parking. The method for finding the reference point is similar to exiting a bay—aligning the hood's horizontal line with the front line (either exactly on the line or slightly delayed). Ensure the wheels do not press the road edge lines. Generally, the required training hours for C1 Subject 2 are 16 hours, while C2 requires 14 hours. Completing the mandatory hours is a basic requirement for taking the Subject 2 test. Training hours can only be increased, not reduced, and additional test items require corresponding extra hours. Each training hour is 60 minutes, with effective teaching time no less than 45 minutes. If you fail Subject 2, you can retake it once. If you fail the retest, the current test session ends, and you must reschedule the test at least 10 days later. If you fail five consecutive test appointments (including retests, totaling 10 attempts), all previously passed subject scores will be voided, and you must restart the learning and testing process from Subject 1.
15
1
Share

Will the Malfunction Indicator Light Turn On If the Three-Way Catalytic Converter Fails?

A faulty three-way catalytic converter can cause the malfunction indicator light to illuminate. The three-way catalytic converter is the most important external purification device installed in a vehicle's exhaust system. Methods to determine the condition of the three-way catalytic converter: Visual Inspection. Examine the exterior of the three-way catalytic converter for any damage or discoloration. Scratches, cracks, or other visible damage may indicate that the converter has been compromised. If there are noticeable gray spots in the center of the converter's protective cover, severe discoloration, or purple marks on the shell, it may suggest overheating issues. Check the Engine Exhaust. Place your hand near the tailpipe outlet to feel the exhaust flow and assess whether the three-way catalytic converter is clogged or if there are any exhaust flow issues. Another method is to open the air filter, remove the filter element, and observe if there is any exhaust backflow during rapid acceleration, which would indicate poor exhaust flow. To evaluate the condition of the TWC (Three-Way Catalyst), also check if the secondary air injection pump is functioning properly. Use an Infrared Thermometer. Compare the temperature difference between the front and back of the TWC using an infrared thermometer. If the temperature difference between the inlet and outlet of the three-way catalytic converter is less than 10°C, the TWC is likely damaged.
15
2
Share

Can car battery replacement be done at home?

For car battery replacement, you can go to a battery retailer where they may offer a trade-in discount for your old battery and provide free installation for the new one. Here is some information about car batteries: Function: The battery plays a crucial role in the operation of a car. If the battery fails to supply power properly, the engine may encounter issues. Car owners should regularly inspect their batteries—weekly in summer and biweekly in winter. Factors affecting battery lifespan: Vehicle condition, road conditions, and driving habits; good driving habits can extend the battery's service life.
9
2
Share
Cookie
Cookie Settings
© 2025 Servanan International Pte. Ltd.