# 4 cylinder not firing changed plug and wires coil pack is firing cylinder is still missing
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2007 GMC Yukon XL 1500 Question: what is causing cylinder not to fire
Tomiko December 31, 2012, 14:19Journeyman
maybe there is something else wrong with the cylinder
Replypushrod, December 31, 2012, 17:54Master
I agree, maybe compression, vacuum leak or you have an injector problem.
Answer #2pushrod January 01, 2013, 12:50Master
Have an injector balance test performed i bet # 4 is not going to pass!