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 (both manufacturers make Toyota’s plugs) 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 and could have widened. 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. Should I pull the plugs and re-gap them at .031? From what I have read–specifically here:


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.


My first guess would be that you may have accidentally disconnected a vacuum hose somewhere, or bumped and cracked a vacuum hose connector.

Thanks for the response. From what I can see all of the hoses and connectors look good. I am starting to think that it may be an issue 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. I am having no other issues with the vehicle and actually using that much gas does not seem all that realistic to me.

Yeah, drive it a while and do a few fillups. Check the mileage on a couple of full tanks.

Texases, does it sound like a possible gas gauge issue to you? Any other suggestions? Thanks again for your help. : ) It just seems to have come out of nowhere.

I wouldn’t expect a gas gauge to give good results over a short distance. See how it works for the rest of the tank.


I think you better check your owners manual again. I strongly suspect that you have the wrong plugs for your engine. Did the new ones even look like the old ones? How is the drivability with the new plugs, any missing, hesitation, power loss?

Keith, Thanks for your reply. The new ones are an exact match in terms of brand and part number (both per the owner’s manual) and appearance. I even checked the individual plug boxes. The drivability with new plugs is great. The truck runs pretty much perfectly. No missing, no hesitation or power loss. That is why it so confusing. Unfortunately. : (

One last check, look in the preventative (scheduled) maintenance part of your owner’s manual. If the schedule calls for spark plug replacement every 30k miles, then you probably do have the right plugs. If it calls for changing every 60k miles, then they should have been platinum tipped plugs and if the schedule was for 120k mile interval, then iridium should have been used.


I checked at autopartswarehouse and the OEM plug is a copper BKR5EYA-11. According to the AutoZone repair guide, the gap should be 0.032" which is typical for a copper tipped plug. Platinum and iridium tipped plugs typically have a 0.040" gap.

Copper tips erode much faster that the platinum or iridium tips, so it it made with a larger diameter electrode. Because the diameter is larger, it does not concentrate the corona as much as the much finer gauged platinum or iridium electrodes, there for it has a harder time developing the spark. The gap is usually made smaller to concentrate the E-field so that the corona develops quicker and the spark is more consistent.

It also extends the life of the spark plug as the tip will erode quicker than the platinum or iridium tips so it has “room to grow” so to speak.

The V-power is not the OEM plug. It is essentially the same, but the ground electrode is a little shorter so that the end of the ground electrode is directly over the center electrode instead of extending past it. This causes the spark to concentrate on that edge where the corona is stronger and gives a more consistent spark. It also gives the spark a better exposure to the fuel air mixture. This plug may not last quite as long as the OEM copper tipped plug though so I would plan on a change interval of 20k miles instead of 30k. The ground electrode will erode much faster than the OEM ground electrode.

BTW, once the fuel air mixture ignites, the strength of the spark is irrelevant. The only advantage a hotter spark has is that it can ignite a wider range of fuel air mixtures than a colder spark, but as long as the spark does ignite the mixture, any extra capacity of the spark is wasted. So all those ads for plugs that give a hotter spark are BS in most cases, they may give a hotter spark, but its about as useful a jackhammer to drive a thumbtack.

Keith, Thanks again for your reply. The recommended scheduled maintenance calls for a spark plug change every 30,000.

I just added more info to my post.

Keith, Thank you for all of that information and the explanation–I really appreciate it. Regarding the new plugs–that is the part number on the box but the box also says V Power. So…did I end up getting the OEM plugs or not? Sorry, I am a bit confused by NGK’s packaging I guess.

With regard to the gap I am still a little unclear what is the correct one with all the different information out there. It is so strange that there are so many different gaps listed in different places. Baffling. If I understand what you wrote correctly, the .032 (recommended by Autozone) would be better for my vehicle based on how copper plugs actually function and re-gapping the plugs would improve the efficiency of the plug and the engine. The gap you are mentioning is essentially what they came pre-gapped at–even though NGK’s site says the gap is .044. I still do not understand the discrepency in gap size there. So just to make sure I am clear on things–.032 would be better than .043 even though that is what the folks at Toyota said?

Thanks again for all your help, man.


It is a little confusing because the OEM plug and the V power plug have the same part number. They are virtually identical, the difference is in the ground electrode. They trim back the ground electrode to the center or edge of the center electrode. The regular plug has the ground electrode extend a little past the center electrode. Its only about 1/8" difference.

Back in the old days of the Kittering ignition system (points), racers used to trim back the ground electrode to the middle of the center electrode to get a more consistent spark. They also used to gap them at 0.025" so they would still spark under very rich fuel air mixtures and high compression, and the lower voltage available from a Kittering ignition at higher RPM’s. I used to do this on my cars, along with indexing the plugs, which probably wasn’t necessary but I thought so at the time.


Gotcha on the difference between the OEM and the V Power. I will just change at 20K vs. 30K.

Interesting about the Kittering systems and the gap and all of that. You seem to know a whole lot about spark plugs and ignition systems! : )

What is the easiest way to move the gap back? Should I use pliers or press it gently against a smooth surface or something else entirely?

Thanks again for all of your advice and sharing your knowledge.


Keith, one more quick question: will lowering the plug gap improve my gas mileage back to where it was?

I would suggest that you fill the tank and clear the trip meter and calculate the actual mpg after a few hundred miles of normal driving.

Thanks. I hope that the change in spark plug gap fixes it. I know that driving home took way more gas than it should have. : (

You can get a sparkplug tool for a couple of bucks and use it to adjust the gap. As long as the plug fires everytime, the gap wont change anything, your gas mileage will only be affected if the plug misfires or the spark is so weak that it doesn’t ignite the fuel air mixture.

The sparkplug tool will have a flat piece with a notch in each side. Slip the notch that fits the electrode over the electrode where it makes its 90° bend and then move it back and forth to adjust the gap. You won’t damage the plug that way.

I’ve been into cars since the time when the Kittering ignition system was the only kind. The “transistorized” ignition systems were aftermarket and not reliable. There has been a lot of changes in the metallurgy used in plugs since then. It is possible that NGK uses a harder material in the ground electrode to slow down the erosion so it will last 30k, I don’t know, but a $3/plug extra is a lot to pay just to trim 1/8" off the electrode.

.43and .44 are not different recommendations, just different translations of the metric gap - 11 mm specified by Toyota. As for the .32 gap, one of two things are going on, either Toyota as changer the recommended gap for this car (it sometimes happens due to in service experience) or you are finding the gap recommended for most cars this plug fits.