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How do you test if a spark plug is working?

posted by  Aye Roll on  Mon Sep 22 05:19 CST 2003
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last visit: Tue Oct 14 21:08 CST 2014
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A clean plug will fire if the coil is providing spark and the rotor is turning, and the wire is not damaged (grounding against something metal).
A test you can use at your own risk is to loosen the plug wires, resting them lightly on their plugs, start the car, and pull them off one at a time. I won't guarantee that you will not get a shock. IF the spark plug is firing, you'll hear a noticable difference in the way the engine sounds with one plug off. Shut it off, put that one back on, pull another one loose and again disconnect it with the engine running. Each time it should make a difference in the sound and idle quality of the engine. Don't run it a long time with the plug wire off- you'll foul the plug and also put raw fuel into the catalytic converter, which is bad for it.
--
Rob Bareiss, New London CT ::: '87 244DL/M47- 221K, 88 744GLE- 202K, 91 244 181K, 88 244GL 145K






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New How do you test if a spark plug is working?
posted by  C  on Mon Sep 22 05:05 CST 2003 >


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