Car Will Turn But Not Start: Here’s the Fix

Car Will Turn But Not Start: Case Study in Mercedes-Benz A Class W177

Vehicle: Mercedes-Benz A Class W177 equipped with the M260 Engine.

Customer Complaint: Car Will Turn But Not Start.

Experiencing a car that will turn but not start can be frustrating, especially when dealing with a sophisticated vehicle like the Mercedes-Benz A Class W177. This article delves into a real-world case study involving this issue, highlighting the diagnostic steps and solutions implemented to resolve it.

Diagnostic Approach

When a customer brought in their Mercedes-Benz A Class W177 with the complaint “Car Will Turn But Not Start,” it was crucial to approach the problem methodically. Initially, I started by checking the Diagnostic Trouble Codes (DTCs), which revealed fault codes related to the exhaust camshaft position sensor.

Step-by-Step Diagnostic Process

1. Exhaust Camshaft Position Sensor Check:

• The first point of investigation was the exhaust camshaft position sensor, which plays a crucial role in engine timing and performance. Given the fault codes, I checked its power supply to ensure it was functioning correctly, which it was.

2. Signal Integrity Analysis:

• Next, I examined the sensor’s signal, which is vital for proper engine management. During this inspection, it became evident that there was an issue with the signal output from the exhaust camshaft position sensor.

3. Wiring and Resistance Check:

• To rule out any wiring faults, I checked the resistance across the relevant wires connected to the sensor. The wiring was intact, and the resistance values were within acceptable ranges, indicating that the wires themselves were not the cause of the problem.

4. Engine Timing Inspection:

• With the power supply and wiring ruled out, I suspected that the issue might be related to the engine timing, given the signals from the exhaust camshaft position sensor. I proceeded to check the engine timing thoroughly, suspecting that the alignment might be off.

Root Cause Identified

Upon closer inspection of the engine timing, it was discovered that there was a fault with the alignment of the exhaust camshaft and the exhaust adjuster. These components are critical in ensuring the proper functioning of the engine, and any misalignment can lead to significant performance issues, including the car turning but not starting.

Solution Implemented

Replacement of Faulty Components:

• The solution involved replacing the exhaust camshaft and the exhaust adjuster, which were identified as the sources of the timing issue. This was a precise task requiring expertise to ensure the new components were correctly installed and aligned to the manufacturer’s specifications.

Final Checks:

After the replacement, I performed a series of tests to ensure that the engine timing was correctly set and that the exhaust camshaft position sensor was functioning without errors. The fault codes were cleared, and the car was tested multiple times to confirm the problem was resolved.

Outcome

Replacing the faulty exhaust camshaft and exhaust adjuster rectified the engine timing issue, and the vehicle no longer exhibited the “Car Will Turn But Not Start” problem. The car started smoothly, and no further fault codes were present, confirming a successful repair.

Conclusion

This case study underscores the importance of a systematic approach when dealing with a “Car Will Turn But Not Start” issue, especially in complex vehicles like the Mercedes-Benz A Class W177.

Proper diagnostic steps, from checking power supply and signal integrity to assessing engine timing, are crucial in pinpointing and resolving the problem. This structured approach not only saves time but ensures that the root cause is addressed, preventing future occurrences.

What are camshaft adjusters?

Camshaft adjusters, also known as camshaft phasers, are integral parts of a vehicle’s variable valve timing (VVT) system. They dynamically change the position of the camshaft relative to the crankshaft, allowing the engine to optimize valve timing during different operating conditions.

This adjustment helps improve performance, fuel efficiency, emissions, and overall drivability.

How Do Camshaft Adjusters Work?

Camshaft adjusters work by advancing or retarding the camshaft timing. This is usually achieved through a hydraulic mechanism driven by engine oil pressure, controlled by the engine control module (ECM).

The ECM monitors various engine parameters, such as speed, load, and throttle position, to determine the ideal camshaft position. When the ECM decides an adjustment is necessary, it activates the camshaft adjuster through a control solenoid.

Key Components of Camshaft Adjusters:

1. Adjuster Mechanism (Phaser): The main component that alters the camshaft position relative to the crankshaft, usually consisting of a helical gear or rotor assembly.
2. Control Solenoid: Regulates oil flow to the camshaft adjuster based on signals from the ECM, allowing precise adjustments to camshaft timing.
3. Camshaft Position Sensor: Provides feedback on the actual camshaft position, allowing the ECM to make real-time adjustments.

Types of Camshaft Adjusters:

– Hydraulic Camshaft Adjusters: The most common type, using oil pressure to rotate the camshaft. It’s widely used because it provides smooth and reliable operation.

– Electric Camshaft Adjusters: Some modern engines use electric actuators for more precise control and quicker response times compared to hydraulic systems.

Benefits of Camshaft Adjusters:

– Improved Performance: Adjusting the camshaft timing allows the engine to optimize the opening and closing of the intake and exhaust valves, enhancing power delivery and throttle response.

– Enhanced Fuel Efficiency: By optimizing valve timing, camshaft adjusters help reduce fuel consumption, especially at low engine loads or during idle.

– Reduced Emissions: Precise control over valve timing helps improve combustion efficiency, leading to lower emissions and better compliance with environmental regulations.

– Smoother Idle and Operation: Camshaft adjusters can help maintain a smooth engine idle and improve overall drivability by constantly adjusting timing to match the current driving conditions.

Common Problems with Camshaft Adjusters:

– Wear and Tear: Over time, camshaft adjusters can wear out, especially if the engine oil is not maintained correctly. Worn gears or mechanisms can lead to timing issues, which affect performance.

– Oil Contamination or Sludge: Dirty or degraded oil can clog the adjuster, solenoid, or associated oil passages, causing the adjuster to stick or malfunction.

– Faulty Solenoids: A malfunctioning control solenoid can restrict oil flow, preventing the camshaft adjuster from operating correctly, leading to performance problems and check engine lights.

– Timing Misalignment: If the camshaft adjuster fails, it can cause incorrect camshaft positioning, resulting in rough running, poor fuel economy, or even the engine not starting.

Maintenance Tips:

– Regular Oil Changes: Maintaining clean oil is essential, as the camshaft adjuster relies on hydraulic pressure from engine oil.

– Timely Inspections: Regular checks of the camshaft adjuster, solenoid, and related components can help prevent issues.

– Use High-Quality Parts: Using recommended parts and oils ensures that the adjuster operates smoothly and avoids premature failure.

Conclusion

Camshaft adjusters play a critical role in modern engine performance, allowing precise control of valve timing to optimize power, efficiency, and emissions. Understanding how they work, recognizing the signs of failure, and maintaining the system properly are crucial for keeping your engine running smoothly.

Camshaft sensor location

Camshaft Sensor Location: Overview and Placement in Vehicles

What is a Camshaft Position Sensor?

A camshaft position sensor monitors the position and rotational speed of the camshaft, providing this critical data to the engine control module (ECM). This information helps the ECM determine the exact timing for fuel injection and ignition, ensuring optimal engine performance, efficiency, and emissions control.

General Location of the Camshaft Position Sensor:

The camshaft position sensor is typically mounted on the cylinder head near the camshaft itself. Its precise location can vary depending on the engine design, configuration, and the number of camshafts (single, dual, or quad-cam engines).

Common Locations of the Camshaft Position Sensor:

1. Front of the Engine:
   Many engines have the camshaft position sensor located at the front of the engine near the timing cover. This placement allows the sensor to directly monitor the camshaft’s rotation as it passes by.
2. Side of the Cylinder Head:
   On some engines, especially those with dual overhead camshafts (DOHC), the sensor can be found on the side of the cylinder head, near the valve cover. This positioning enables easy access to the camshaft.
3. Rear of the Engine:
   In some vehicles, particularly those with V6 or V8 engines, the camshaft position sensor might be located at the rear of the engine near the firewall. This position can be more challenging to access and may require removing some components.
4. Near the Timing Chain or Belt:
   Engines that use a timing chain or belt may have the camshaft sensor positioned close to these components, allowing it to measure the exact timing and rotation of the camshaft in relation to the crankshaft.
5. Integrated with Camshaft Adjusters or Actuators:
   In some advanced engines, the sensor may be integrated within the camshaft adjuster or positioned near VVT (Variable Valve Timing) components to closely monitor changes in camshaft position.

Signs of a Faulty Camshaft Position Sensor:

• Check Engine Light: A common sign of a camshaft sensor issue, usually accompanied by a fault code related to camshaft timing or position.
• Engine Misfires: Incorrect camshaft data can lead to misfires, poor acceleration, or rough idling.
• Starting Issues: A faulty camshaft sensor can cause hard starting or the “Car Will Turn But Not Start” problem due to incorrect timing information.
• Reduced Engine Performance: Loss of power or irregular engine behavior when the sensor fails to provide accurate data.