I would check the gap. I usually find the gap is either large or small depending ont he plugs.

I always check my gaps before I install the plugs. I also check the gap according tot he old plugs too to see if there are any discrepencies in the gaps.

I would set the gap to factory specs for the gap.

The plugs you buy can probably be use din other cars, so my thinking is the gap may or may not be correct for your car.

Alon

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'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon - Sold
2006 E350 Wagon - 368 - Dead
2015 GL350 Bluetec - 197U