Finding a misfire using AESwave’s uScope - weak ignition coil

Summary

In this video, a technician troubleshoots a misfire issue in a 2002 Ford Taurus, focusing on cylinder number one, which is showing a P0301 misfire code. Using Mode 6 misfire data, a new budget-friendly u-scope, and a test light, the technician identifies a weak spark from the ignition coil, particularly under load. After analyzing secondary ignition waveforms and comparing cylinders, the technician confirms that the coil is faulty and needs replacement. This video provides a clear, step-by-step guide on diagnosing ignition issues and highlights an affordable tool for automotive diagnostics.

Takeaways

• 😀 The vehicle in question is a 2002 Ford Taurus with a cylinder number one misfire (P0301) fault.
• 😀 Mode 6 data reveals that cylinder number one has the highest misfire count, suggesting it is the problem cylinder.
• 😀 The misfire issue is intermittent, primarily occurring under load, though it is not noticeable at idle.
• 😀 The ignition system is suspected to be the cause of the misfire, especially since the coils on Fords are known to fail.
• 😀 The video demonstrates a simple test to isolate ignition problems using a U-scope, a more affordable diagnostic tool.
• 😀 The U-scope was used to observe secondary ignition waveforms for cylinder number one, which revealed a weak spark line.
• 😀 A capacitive pickup was employed to capture single cylinder secondary ignition waveforms, showing a bad spark for cylinder number one.
• 😀 The coil's malfunction was suspected because the spark line for cylinder one failed to reach a proper threshold, indicating a weak spark.
• 😀 The video also shows a quick test comparing the spark gap for cylinder number five (a known good cylinder) with cylinder number one, confirming a weak spark in the latter.
• 😀 The issue is traced to a faulty coil, with the test revealing that the spark for cylinder one is not jumping the required gap, leading to misfire under load.

Q & A

What is the main issue being addressed in the video?

The main issue is a misfire in cylinder number one of a 2002 Ford Taurus, specifically related to a P0301 misfire fault.

How can misfires be monitored on a Ford vehicle?

Misfires can be monitored through Mode 6 data, which displays misfire counters for each cylinder. For this particular case, cylinder number one had the highest misfire count.

What recent maintenance was performed on the vehicle before the misfire occurred?

The vehicle had its spark plugs and wires replaced recently, yet the misfire persisted, particularly under load.

Why was the ignition system targeted for diagnosis?

The ignition system was chosen to be tested first because the coils in these Fords are known to fail, and previous experience suggested that a coil failure could be the cause of the misfire.

What tool is being demonstrated for diagnosing the misfire?

The tool being demonstrated is called a U-Scope, made by AES Wave. It's an inexpensive alternative for performing ignition system diagnostics, especially for secondary ignition waveforms.

How is the U-Scope used to capture ignition events?

The U-Scope is used with a capacitive pickup attached to the spark plug wire, capturing the ignition waveform for each cylinder. The scope can be adjusted for time base and trigger levels to isolate specific ignition events.

What does the waveform for a good ignition event look like?

In a good ignition event, the waveform shows a clear and stable spark line, indicating proper ignition. The video demonstrates this with cylinder number one and other cylinders as comparison.

What is indicated by a weak or absent spark line in the waveform?

A weak or absent spark line, as seen in cylinder number one, indicates a problem with the ignition system. This could be a failing coil, resulting in a weak or no spark under certain conditions.

How was the coil's performance tested using a test light?

A test light was used to check the spark's ability to jump across a gap. The test revealed that the spark from cylinder number one was weak and could not jump a significant gap, confirming that the coil was failing.

Why doesn't the misfire occur at idle, but only under load?

The misfire is not noticeable at idle because the ignition system may still be able to produce a weak spark under low demand. However, under load, the system struggles, and the misfire becomes apparent due to the increased demand on the ignition system.

What does the speaker suggest as the solution to the problem?

The speaker suggests replacing the faulty ignition coil, as the weak spark confirmed that the coil was malfunctioning and causing the misfire.