Introduction
Dealing with car troubles can be frustrating, especially when symptoms are misleading. Like many car owners, I recently faced a perplexing issue that turned out to be a combination of problems, highlighting the importance of thorough diagnosis. My experience centered around a faulty timing belt and a camshaft sensor, and I’m sharing my story to help anyone encountering similar automotive mysteries. If your car is acting up and you suspect a sensor issue, especially related to the camshaft, this detailed walkthrough might offer some valuable insights.
The Initial Problem: Sudden Engine Stalling
It all started with sudden engine stalls. Without warning, my car would simply shut off while driving. There were no предшествующие signs of rough idling or unusual noises, it just abruptly stopped. Restarting the engine immediately proved impossible, which was quite concerning and, frankly, a little dangerous when it happened on a moderately busy street.
First Suspicions and the Timing Belt Revelation
Initial thoughts ranged from fuel delivery issues to electrical problems. However, after some online research and suggestions from fellow car enthusiasts, a timing belt check was recommended. To my surprise, upon inspecting the timing belt cover, the problem was immediately obvious – the timing belt had snapped completely in half! This was shocking because I had replaced it less than a year prior.
Timing Belt Replacement and a New Setback
For the replacement, I opted for a Subaru brand timing belt this time, learning from the previous experience. While the last belt was from a reputable aftermarket brand, the failure made me reconsider. Working with a friend, we installed the new timing belt and discovered another culprit: the tensioner roller had seized. The bushing was completely stuck, likely a contributing factor to the premature timing belt failure. Fortunately, I had a spare tensioner, and we replaced it along with the belt. With everything reassembled, the car started perfectly and ran smoothly. I was relieved, thinking the ordeal was over.
Déjà Vu: The Stalling Returns and Check Engine Light
My relief was short-lived. Later that evening, while driving to the store, the exact same issue recurred. The car stalled again, suddenly and without warning, mirroring the initial problem. This time, however, there was a new development – the check engine light illuminated. This was unusual for my car, and it prompted me to check the error codes. The diagnostic codes revealed a coolant temperature sensor issue, a knock sensor problem, and, crucially, the camshaft position sensor again.
Deep Dive into the Camshaft Sensor
With the camshaft position sensor code reappearing, we focused our attention there. Visually inspecting the sensor and its wiring harness revealed no obvious damage. Interestingly, my friend managed to start the car, and it idled without stalling this time. We tried wiggling and probing the wiring harness to see if we could induce a stall, suspecting an intermittent connection, but the engine kept running.
Signal Testing and Wiring Confusion
Our next step was to investigate the signal from the camshaft sensor to the ECU (Engine Control Unit). We confirmed continuity in the wiring harness from the ECU to the sensor. However, we lacked an oscilloscope to analyze the sensor signal waveform. As a basic test, we checked for voltage generation by waving the sensor past a metal object, confirming it was producing some output.
Wiring became a point of confusion. The aftermarket sensor and my DIY connector replacements didn’t follow the original Subaru wiring color scheme. Consulting various manuals, we attempted to decipher the correct wiring order. Initially, we made an educated guess based on color matching (white to white, red to red, black to black/shield). This resulted in the engine starting but running poorly, with limited RPM and unusual noises. This experiment, although unsuccessful, confirmed that the camshaft sensor was indeed crucial for the engine to run correctly, as the car wouldn’t start at all with the sensor completely disconnected.
The Correct Wiring and a New (Used) Sensor
Fortunately, I had preemptively ordered a used camshaft sensor online, anticipating potential sensor failure. Sourcing a specific wiring diagram (from my friend’s access to professional mechanic resources) proved to be the breakthrough. We discovered the correct wiring configuration for my setup:
- ECU big black wire (shield) –> Harness yellow wire –> Sensor black wire
- ECU white wire –> Harness white wire –> Sensor RED wire
- ECU small black wire –> Harness black wire –> Sensor WHITE wire
With the new (used) sensor correctly wired according to this diagram, the car started and ran perfectly smoothly. A test drive, with my friend following as a precaution, confirmed that the stalling issue was resolved. However, the check engine light reappeared.
The Final Piece: A Loose Knock Sensor
Back home, another code scan revealed a knock sensor error. Recalling the earlier work, I realized I had forgotten to properly tighten the knock sensor during the initial repairs. It was indeed completely loose. Tightening the knock sensor finally resolved the check engine light.
Conclusion: Lessons Learned in Camshaft Sensor Diagnosis
This troubleshooting journey, while initially frustrating, provided valuable lessons in diagnosing car problems, particularly those involving sensors. It highlighted the importance of:
- Thorough Inspection: Don’t just focus on the most obvious symptom. Investigate related components, as seen with the timing belt and tensioner.
- Accurate Parts: Using genuine or high-quality replacement parts is crucial, especially for critical components like timing belts.
- Systematic Diagnosis: Follow a logical process of elimination. Don’t overlook seemingly minor details, like the check engine light.
- Correct Wiring: Sensor wiring is critical. Incorrect connections can lead to various engine performance issues.
- Patience and Persistence: Troubleshooting complex car problems can take time and effort. Don’t give up easily.
Currently, my car is running smoothly with no check engine lights. Hopefully, this detailed account of my camshaft sensor and timing belt saga proves helpful to others facing similar automotive challenges. Always remember to consult repair manuals specific to your vehicle and consider seeking professional help if you’re unsure about any diagnostic or repair procedures.
