I bought an 06 5.3 motor almost a year ago, that was very low mileage, so I reused the spark plugs that came with the motor. My PCM is using an 02 OS and was tuned with EFILive.

Now heres the question. The factory plugs in 2006 were gapped to .040, and have not been touched. My PCM is setup with the spark dwell tables for a .060 gap spark plug. Now my truck has been tuned with the .040 gap spark plugs in the truck, and runs decent, but I am wondering if switching to .060 gapped plugs will make it run better or worse since it is already tuned for what its got. I am going to get a new tune on Tuesday next week, and am debating if I should change the plugs before then to see if it makes any difference.

But then I have also read that just because the factory plug gap is this or that, doesn't mean it is the best gap for my application because I have a decent mod list. So how important is spark plug gap as far as tuning with LS based engines. Would it be worth it for me to buy a new set of plugs (either NGKs or ACDelco platinums) and gap them to .060, or is there a better gap that I should be using?

 

I had the exact same problem but the opposite, last night i switched my to .04 like they are supposed to by and it runs better now! IMO you should go by the gap that equals your operating system.. For you your is a 02 operating system so you should go with a 02 spark plug gap.

 

My TR6s are gapped at .032 with no issues.

 

I have a set of ngk tr55s what should the gap be on these !!

 

I got a 2005 5.3 and put it in my 2001 went to the parts store and got ac delco iridium... Unsure of the gap(think I got plugs for an 05) mail order tune due to cam swap... I didn't know different years had different gaps. Did I make a mistake? Sorry to thread jack