2003 Toyota Tacoma 2.4L Spark Plug Gap Question - Gas Mileage Issue

Hello Everyone,

I recently changed the spark plugs on my 2003 2wd 2.4L Tacoma with 122,000 miles. I do not think the plugs had ever been changed--I recently purchased the vehicle. I used the NGK direct replacement plugs recommended by Toyota in the owner's manual (copper [V Power series], not platinum or Iridium)-but I did not buy them from Toyota. I gapped them at .043. There is NOT a sticker under the hood listing the gap specification--the sticker only lists valve clearance. When I took the new plugs out of the package initially they were pre-gapped at about .032 / .033. I looked all over the place on-line and even called multiple dealerships looking for the proper spark plug gap. I received a bunch of different responses. A few sites said .031 while others said .043 or .045. One dealership said .043 and another said .045. Both NGK and Denso's websites say .044 is the correct gap. The plugs that I removed from the vehicle were all gapped at between .043 and .048--but they were very worn. The vehicle runs fine but my gas mileage appears to have dropped off drastically. I was not having issues with gas mileage prior to changing the plugs. This confuses me as the new gap is comparable to the gap from the old plugs. It also could be a strange coincidence and there could be a problem with the gas gauge. According to the gauge I used about 2 gallons of gas on my 10 mile drive to work--2 gallons should last about 38 miles or so (as you all probably know). I am having no other issues with the vehicle and *actually* using that much gas does not seem all that realistic to me. But....should I pull the plugs and re-gap them at .031? From what I have read--specifically here:

http://www.automotiveforums.com/t363441-plug_gap.html

even the FSM contradicts itself and says .043 on one page and then .031 on another.

Not that I think it is necessarily connected but I also changed the air filter (Fram) and the oil and oil filter (replaced with a Toyota filter and Castrol 5w 30). I have not done anything else to the vehicle.

I apologize in advance if this has already been covered. I searched but did not find it. I am totally at a loss here and any assistance or insight anyone can provide would be greatly appreciated.


Thanks in advance.

-Scott

 

Hi Scott,

My Haynes manual confirms .043 for all 4 cylinder engines (may want to pick one up). As for the sudden loss in MPGs, perhaps something got messed up a bit with the change. Confirm plugs are properly gapped and seated in the sockets. I had a loose plug once when I attempted to change plugs in a hot engine and didn't realize it for a couple of weeks worth of poor MPGs in an Escort I had. Maybe some light damage to the coilpack/wires when removing? Are the wires seated properly?

Not thinking it's related to the air filter, but I would suggest OEM replacements (not a fan of Fram myself). Oil is correct but would double check the oil level to make sure you're topped off properly. Could be the gage as you note. For me, a steady 102-106 miles per 1/4 tank with current gas and temperatures. Maybe longer than usual start-up idle? More stops than normal? Cold temperatures? Hard to say, but I'd worry more after a couple of tanks where it's really obvious you have a problem.

Kevin

 

I think my NGK's were pregapped at about .031 or so.

Not sure though.

 

Maybe you purchased a higher ethanol blend of fuel without noticing??

 

Thanks for the responses everyone. I will check into all that. A haynes MAnual is definitely on my list for the near future.