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What might cause a sporadic misfire on a 99 GMC 6500 with 454 gas engine?


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Wiki User
2014-10-31 18:48:55
2014-10-31 18:48:55

Could be,

spark plug(s),

contaminated fuel (water),


Related Questions

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the misfire my be caused by improper sparkplug gaps or bad injectors

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The distributor could be failling, there might not be enough fuel or air reaching the engine (too much is bad too), or your spark plugs/wires are damaged or not to spec.

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The spark timing might be too advanced. At high temperatures and RPM an advanced spark might cause preignition, and engine knock. That's only likely to happen if the engine is modified though. Other than that, check the air and fuel filters are clean, as the harder the engine has to work the more a clean flow of both is important.

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I'm not a mechanic / technician but it might be the spark plug , spark plug wire , not the proper air / fuel mixture to that engine cylinder , and there are probably other causes

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