spark plug gapping for 2002 yukon xl

[PDidHe]

ok so my delima is that my 2002 yukon xl 1500 5.3 origanally had a spark plug gapping of 0.060 but some where down the road gmc decide to change that i think it is indicative to the specifcation of the engines feul econimy why would they put a gapping of 0.040 in place of it? to me i think this would only give you worse gas milage? is there anyone out there who can help me uderstand why i should not keep gapping my pregapped spark plugs from 0.040 to 0.060? please make me understand the benifit of this

 

[SunlitComet]

it was sort of a misfiring issue actually but they also changed the metal used in spark plug and that is why they said the gap was changed. You should be at .040. What you buy no should be and you should not attempt to alter it. if it has been altered trash the plug.