Spark plugs & wires (mpg dropped)

2001 Tacoma with 122000 miles on it. I track manually (math) track my miles per gallon meticulously when I refill gas. MPG dropped from 18 to 16

Replaced spark plugs with 6 Denso plugs and spark plug wires & cleaned the MAF sensor & put in new brake pads. My mechanic friend said I should've went 3 NGK and 3 Denso (something about one side generating a lot more heat than the other). I had asked the oreilly worker for copper spark plugs but when I looked on the receipt, it said Nickel spark plugs any cause for concerns? I would think the MPG would remain the same or maybe even increase with new plugs in?

 

How many gas tanks have you tracked since replacing the plugs and wires? 16 vs 18 mpg is within normal variation and likely has nothing to do with your new equipment. Did you get dual prong spark plugs? NGK or Denso is fine. You don’t need three here and three there.

 

^ this. (dual electrode)

 

Sounds like somebody you should quietly chuckle at after leaving

Biggest thing that can impact your MPG spark plug related is the gap. No, they are not "pre-gapped". Get one of those coin looking gap tools and gap to factory spec.... 0.043" IIRC

 

Not going to disagree on the importance of having a proper gap. However, gaping dual electrode plugs can be challenging with the tool you suggested. A wire gaping tool might be easier to use.

 

What is the part number on the plugs you installed?

 

FWIW and based off of what I've seen multiple places here on this forum... Toyota 4.0 ran one bank NGK and the other Denso. Sounds goofy but there are multiple members claiming this was the case on the first spark plug change, so... Would I run that?... Why? The plugs I showed above ran great, I'd bet they had 3xs the recommended 30k.

 

That's correct. The working theory is that was Toyota's way of keeping both suppliers happy.

Digiratus above had the best point: there are lots of Denso plugs out there, did you actually get the right ones for your truck? Asking for copper and getting something different sounds like you didn't get what you needed.

The exact part number should be in the owner's manual.

 

When you find a wire gapping tool for .043 please let everyone know. Last time I did an extensive look for one, I came up completely blank.

 

If you got the right plugs (

$18 Denso K16TR11 Spark Plugs, Pack of 4

Denso K16TR11 for the V6), these are copper cored and nickel tipped electrodes.

 

Commendable to be “learning to adult” and keeping notes on your mileage. How many variables have you accounted for? Humidity, average temperature, elevation change, using AC, average speed, etc. all can contribute to changes in mileage. My mileage will fluctuate within a 2 mpg range depending on these factors pretty frequently.

I’m not sure what reasoning led from losing 2mpg to identifying it as being 6 bad spark plugs and 3 bad wires. How would you identify that all spark plugs and all the wires went bad simultaneously and further more were the old spark plugs looked at and identified as being out of spec? It would be unusual for spark plugs to cause an instantaneous loss of mileage and not show any major signs of a recent failure.

 

I also have never run dual electrode plugs like Digi mentioned

 

I'm sure you've got different spec'd plugs for your turbo though?

 

Yes, completely. Though before the turbo I might have had some in there for maybe 6 months from the previous owner? Never had to gap duals I suppose...though I'd assume the curvature of the coin gapper would fit. Just do the right side first (expand) then move it counterclockwise and do the left side (shrink)?

 

Any dual electrode plugs should be ready to go right out of the box. It's not realistic to jam a gapping tool down in there. If the gap looks off or damaged return the plugs and get another set

 

Just want to point out that "dual" electrode plugs are for longevity only. When one electrode wears down enough, the other one takes over.
The plug will not spit two sparks at a time.

Electricity will always take the path of least resistance. Always. Thus, only one electrode will spark when the juice is supplied.
Also remember that the spark prefers to jump to/from sharp points. Corners. So, the discharge spot will move to the best, sharpest point as the old one wears.
This "wear" is caused by metal leaving with the spark. A cathode by definition. Just a wee bit with each and every spark, but over time...
There lies the beauty of gold & platinum. Neither of those metals give themselves up easily. They resist eroding (wearing) extremely well.

 

I'm sure it doesn't matter, and it would be close enough... but here is a depiction of a wire gauge vs coin gapper and why the coin gapper wouldn't be as accurate:


With the wire on the left side, it takes the slight curvature of the electrode into account, where as the coin gapper with the continuous taper would be "different". Is it enough to matter... probably not.

 

might as well measure the curvature offset while you have it CADed (rightmost vertical line to the centerpoint of the arc)... then reduce the 0.043" by that much

 

it was just a quick sketch, and it was not to scale at all.. already closed fusion

 

Can't believe they aren't all running quad tips smh... twice the life right?!