Hey there, couple of months ago i changed the plugs from the stock platinums to the iridium mileage was around 88,000 average gaps on the old plugs was .049. Also changed the air filter to a K&N. This was all done roughly mid tank of chevron gas and ended up getting roughly 19.9 mpg. Every tank after that has been way lower mpg best was a recent tank of 76 brand at arround 15.6 mpg i'm stumped as to why the sudden drop-- not sure if it could be the irridium plugs which i carefully gapped to the factory .43 or what.

 

They come pre gapped so you shouldn't have needed to adjust them.

 

I would never gap a spark plug with a precious metal tip, you could damage it or break it off completely if done wrong.

They do come pregapped, so unless you dropped it after taking it out of the package, I wouldn't worry about it too much. Just check the gap to make sure its within spec and install.

 

Try putting the original filter back on; K&N filters can be a problem depending on how much oil was put on the filter. Excessive oil can cause problems with the MAF and a replacement MAF is expensive.

 

If the MAF is oiled up from using an oiled air filter, it will need a clean before you will notice any improvement.

+1 what the others said about iridium plugs.. don't gap them.. they should be correct out of the box. If you still have issues.. put the old plugs back in and see if it change..

 

why do people think it needs to be gapped? and since its pre gapped how the heck did he gap them some more lol?

 

I haven't checked the Maf sensor but just for the info i've never seen a plug that was gapped correctly out of the box -- maybe straight from Infinity's service department but stick a gap measuring tool in a new plug and itt'le not only be off but none of them will match! And yes if changing the gap use the correct tool that allows you to gently bend the tab in or out without touching the electrode tip and for sure dont tap it against anything esp with the gapping tool in the plug.

 

^lol and uve done a better job of gapping the plugs? no ones else had any issues using plugs right out of the box.

 

There is usually a warning on the box telling you not to try to gap the plugs.. it very easy to snap the electrode on platnium or iridium plugs, so even if you have the correct tool to set the gap, just measuring the gap can damage the electrode. Unless you can measure the gap without touching the electrode at all.

And with modern high power ignition systems, minor differences between plug gaps isn't going to cause any issues like it did with older kettering systems.