I was wondering if anyone here has any advice or information directly related to spark plug gaps and MPG. With the number of things I read and heard over the years, it all got extremely confusing and I just don't know what to believe anymore.

It all started out when it was time to replace my stock 2000 Accord V6 plugs. They were replaced once before by the previous owner (probably a shop telling them to do it every 30k miles). I pulled out OE NGK (4363) PZFR5F-11 Laser Platinum plugs but they were gapped at .033 instead of the recommended .044. I didn't think much of it then and got 6 new plugs. They were exactly the same type again that came from the factory (PZFR5F-11) but they also came gapped at .033 out of the box. So I regapped them to .044 like the under-hood sticker says to do and didn't notice any difference in how the car ran while driving or at idle, there also wasn't any problems with the old plugs either they just looked a little worn out. I did however notice a good drop in MPG as in I was getting about 80-100 miles less per full tank. I regapped the new plugs back down to .033 like the old ones and my MPG instantly went back up. I find this odd and was wondering if anyone here has any input on this.

From what I read, a smaller gap will burn hotter with more amps resulting in more efficient combustion, also I assume a high temperature plug will have the same effect as long as it doesn't melt it or the pistons.

But, I also heard people say many times that a larger gap will create a larger spark and that will result in a more complete combustion, thus giving more power which goes hand in hand with more MPG.

But, another thing I read is that a smaller gap will arc over/spark sooner causing the spark timing to advance and that will gain you more MPG. Not sure if the J series V6 has knock sensors or not, if not this theory would make sense.

Now my personal experience has also been contradicting like the above statements. On my 1998 Durango with a 5.2L V8 I ran NGK V power coppers. It has a distributor and multi port injection. Changing the gap from the factory .044 to .054 gave me a decent MPG increase. Now on my Accord V6 that has a coil on plug system and multi port injection I tried a .050 gap and got horrible MPG, no misfiring or hesitation though just worse gas mileage. And it seems changing the gap from the factory .044 to .033 made a big improvement in MPG. I can't find any decent explanation for any of that. The only differences are a dizzy vs. COP and coppers vs. platinums. I read that only advantages to platinums are that they are much easier to spark so they work well in older weaker ignition systems and they last much longer, usually around 100k vs. the 30k for coppers.

Is it possible I'm somehow trading power for MPG? I don't drive hard enough to notice any power differences, I just try to save as much fuel as possible when I drive. I'm always looking to maximize my MPG anyway I can. If anyone here can explain anything or has anything to say about any of this, please comment.