Auto Service Professional

OCT 2018

Magazine for the auto service professional

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14 A S P O c t o b e r 2 018 these pattern selections are available. ese units have an ignition scope side and a lab scope side. Now with the advent of COP and DIS ignition systems we can still monitor each cylinder's sec- ondary event one at a time to not only determine whether we have good spark but can detect a lean cylinder, rich cylinder, low compression cylin- der and internal coil carbon tracking problems by using a COP wand. ere are several COP wands on the market. e one I use the most is the one from It looks like a small fly swatter. When we lay the probe on the coil we are inductively picking up the collapsing mag- netic field from the coils firing. Keep in mind I g n i t i o n W a v e f o r m D i a g n o s t i c s Figure 5: Toyota secondary (after new cap and rotor) Do you see a much longer spark duration period? And would you believe the misfire is now gone? Figure 4: Toyota 2.4L (intermittent miss/buck) This was captured during idle no-load conditions. Notice the very short spark duration period of the spark line. It is actually below 1 millisecond. The tech has previously replaced the spark plugs with no improvement. Since this is a cap and rotor equipped engine he proceeded to replace the cap and rotor and plug wires. Remember that on distributor-equipped engines there are two authorized air gaps — the rotor air gap and the spark plug air gap.

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