Waste spark system??????

sst1988 · 09-07-2008, 03:40 PM

No Spark Line, Open Spark Plug Cables. are parade and raster patterns with no spark lines. These are more examples of open-circuit conditions, which usually indicate disconnected or open plug cables.

Long, Low Spark Line, Few Coil Oscillations: Fouled Plug or Shorted Coil. are raster and parade patterns that show a long, low spark line and few oscillations for one coil. This usually indicates a badly fouled plug or plugs, or a shorted coil.

High, Short Spark Line: Lean Mixture or Wide Plug Gap. Figs. are raster and parade patterns that show a high, short spark line for one coil. This is a common sign of a lean mixture or very wide plug gap in one or both cylinders for that coil. If the problem is a lean mixture, it may be due to a vacuum leak that affects only one cylinder.
Mistakes To Avoid Jumping Spark Line. an unstable spark line for one coil. It appears to jump up and down at random. This is often caused by a sticking or worn valve in one cylinder that causes an uneven air/fuel ratio.

Upward-Sloping Spark a spark line for one coil that slopes upward as it ends. This is similar to the jumping spark line , but usually indicates sticking or floating valves if it appears at all speeds. It also can indicate burned valves, wide plug gaps or a vacuum leak that affects several cylinders.

False Trigger: Bad Crankshaft or Camshaft Sensor. is a raster pattern with a false trigger signal on the waveform for one coil. This may indicate a bad crank or cam sensor, and may appear randomly for various cylinders. Other causes may be a bad ignition module, radio frequency interference (RFI) with the ignition module, shorted sensor wiring or a dirty or bent trigger wheel for the sensor.

Check Waste-Spark on Parade

To close this report, we'll point out an extra feature of digital lab scopes that split the superimposed waste-spark DIS firing event. When a scope displays a waveform for each cylinder, you can compare the waste spark to the power spark for each cylinder. If the wastespark firing line seems higher than normal, or higher than the waste spark for the other cylinders by comparison, you're probably looking at high resistance in the portion of the circuit to that cylinder.

The problem might be an open or high-resistance plug wire or an accidental gap at the connection to the coil or the plug. Whatever the source, the high resistance can lead to a misfire. If you recognize this symptom, you're on your way to solving the problem.

09-07-2008, 03:40 PM	#3
sst1988 Member Join Date: May 2008 Location: Pittsburgh, Pa Posts: 302 Likes: 0 Liked 0 Times in 0 Posts	Re: Waste spark system?????? No Spark Line, Open Spark Plug Cables. are parade and raster patterns with no spark lines. These are more examples of open-circuit conditions, which usually indicate disconnected or open plug cables. Long, Low Spark Line, Few Coil Oscillations: Fouled Plug or Shorted Coil. are raster and parade patterns that show a long, low spark line and few oscillations for one coil. This usually indicates a badly fouled plug or plugs, or a shorted coil. High, Short Spark Line: Lean Mixture or Wide Plug Gap. Figs. are raster and parade patterns that show a high, short spark line for one coil. This is a common sign of a lean mixture or very wide plug gap in one or both cylinders for that coil. If the problem is a lean mixture, it may be due to a vacuum leak that affects only one cylinder. Mistakes To Avoid Jumping Spark Line. an unstable spark line for one coil. It appears to jump up and down at random. This is often caused by a sticking or worn valve in one cylinder that causes an uneven air/fuel ratio. Upward-Sloping Spark a spark line for one coil that slopes upward as it ends. This is similar to the jumping spark line , but usually indicates sticking or floating valves if it appears at all speeds. It also can indicate burned valves, wide plug gaps or a vacuum leak that affects several cylinders. False Trigger: Bad Crankshaft or Camshaft Sensor. is a raster pattern with a false trigger signal on the waveform for one coil. This may indicate a bad crank or cam sensor, and may appear randomly for various cylinders. Other causes may be a bad ignition module, radio frequency interference (RFI) with the ignition module, shorted sensor wiring or a dirty or bent trigger wheel for the sensor. Check Waste-Spark on Parade To close this report, we'll point out an extra feature of digital lab scopes that split the superimposed waste-spark DIS firing event. When a scope displays a waveform for each cylinder, you can compare the waste spark to the power spark for each cylinder. If the wastespark firing line seems higher than normal, or higher than the waste spark for the other cylinders by comparison, you're probably looking at high resistance in the portion of the circuit to that cylinder. The problem might be an open or high-resistance plug wire or an accidental gap at the connection to the coil or the plug. Whatever the source, the high resistance can lead to a misfire. If you recognize this symptom, you're on your way to solving the problem.