Deck plate mod - mpg change?

Granted I have a very small sample size, but I think maybe my mpg dropped 1 or 2 after the deck plate mod. Is that expected?

 

could be, did you disconnect battery for an hour to reset the ECM so it readjust the fuel air mixtures? do that then after a couple of days fill up and check you mpg

when you let more air into the engine it also sends in more gas so if you aren't getting a power increase from it then gas mileage could drop slightly depending on your driving style

 

No where near an hour. Actually, I didn't disconnect the battery at all. I pulled the EFI fuse. I found that odd, but that's what the instructions I found said.

 

well some say 10-15 minutes is all it takes but I do an hour just so im 100% sure all power has drained and it resets. what you are doing is waiting for the backup power to drain out and get to zero so the memory is cleared and no two cars are the same as to how long it takes to happen so I do a little overkill to be sure. probably 1/2 hour is all the overkill it really needs but I disconnect it and go eat lunch and check my emails, cut grass or something, then hook it back up. just write down your radio station presets first so you can reprogram them.

maybe the EFI fuse does it too but I do the battery just to be sure everything loses power and resets.

 

I've pulled the EFI fuse, and disconnected the battery for a while. Both reset. I think if you disconnect the battery, and pump the brakes it will also discharge all capacitors quickly. Pretty sure they are all options.

 

Yea....that could be possible.

I had a K&N filter w/ deckplate mod and gained about that....1-2mpg in my old 96 3.4 many years ago when I owned it.

 

Highway mileage should actually go up slightly. I did mine years ago and the mileage went up about 14-16 miles on a tank. I was getting a pretty consistant 290 range on the HWY and the week after deck plate was the first time I broke 300 on a tank. It stayed at about 305-310 miles and took right at 16 gals on a fill up afterward.