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You can now use your heritage Vantage GMM to view ignition patterns without buying the KV Module.By using the Wyzeprobe coil-on-plug ignition probe and special test lead. Here is a case study on a 1994 GMC Jimmy with the 4.3 Vortec engine that had a intermitant misfire under a light load.   With the cop-probe positioned across the coil wire near the coil this is the pattern first seen.(vantage above left) (Fluke-98 above right). The patterns look terrible.There is definitely an ignition problem here.  The Vantage Ignition waveform above is showing a burn time of only .4ms, and the coil oscilations are weak.Normally to view this pattern the vantage high volts is set to 5volts, In the above capture you can see that it is set at 14volts: The coil is actually outputting a higher than normal kv.  I found the coil wire to distributor cap centre terminal severly coroded,replaced the coil wire and cleaned the centre terminal,and continued testing. The intermitant miss was still present even thou the burn time is now good. The probe is still in the same position giving us this super-imposed pattern  We can now see the missfire,the burn voltage is fluctuating. By now moving the probe to each individual plug wire, we were able to identify the bad cylinder. The truck ended up getting new wires,plugs, and a cap/rotor. Here is the final good waveform.  The Wyzeprobe cop-probe works on most ignition systems, COP, DIS, Conventional, Coil in cap, Coil Near Plug. Click here to see more information on using the Vantage for ignition testing |
