Spark-Plug Misfiring —mechanism studies
600038
01/01/1960
- Event
- Content
- SPARK-PLUG MISFIRING due to lead fouling occurs when compounds of low electrical resistance are deposited on the spark-plug ceramic under low-temperature operating conditions and are subsequently raised to high temperature by operating the engine at higher speeds and loads.Spark-plug temperature (as measured with thermocouple spark plugs) was found to be the most important variable governing misfiring. Deposit composition together with spark-plug temperature governs the shunt resistance of the spark plug. When this shunt resistance becomes sufficiently low, misfiring occurs.Misfiring severity was shown to decrease when:
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1.
Deposits were accumulated at successively higher temperatures.
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2.
Engine conditions during deposit buildup were varied to yield higher maximum spark-plug temperatures although the average temperature was unchanged.
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3.
A phosphorus compound was added to the deposit accumulation fuel.
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4.
Fuel octane quality was increased to eliminate knock during accelerations.*
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1.
- Pages
- 8
- Citation
- Julien, H., and Neblett, R., "Spark-Plug Misfiring —mechanism studies," SAE Technical Paper 600038, 1960, https://doi.org/10.4271/600038.