Interesting trip to dealer...

Last week, I changed the plugs in my Tacoma (it was way overdue) and figured I'd get better gas mileage from the new plugs...was told to gap plugs at 43, old plugs were gapped at 74...imagine my surprise, when I lost 5 mpg! Today I checked with my dealer abt this, and he said "you put the wrong plugs in your truck" (I put NGK plugs in) So...trip to dealer to buy Denso plugs...7 bucks a pop...ask parts man what to gap the plugs at "They come pre gapped" just put them in...get home, check the gap, 2 were gapped at 40, 2 were gapped at 42, one at 41, and the 6th one at 42...Denso says to gap them at 44...so, going out to change plugs...again! wish me luck!

 

Look at some of the other threads on this subject. I changed mine about 70k, and just like the other threads said, one bank was NGK and the other was Denso. I got the Denso from the dealer at $3. and change, looked on line and they were under $3 but with shipping went to dealer. Even brand new plugs need gap checked as they could have been knocked around, or just not right from factory. Make sure you put a little "never seize" on threads before install. My old ones were well worn, but nice and dry.

 

Your truck comes from the factory with 3 NGK and 3 Denso plugs.

 

If the plugs are correct fit and gapped at spec they shouldn’t drop mpgs. Are you sure they were installed and gapped correctly?

They do not have to be Denso. That’s bullshit.

 

Okay...update...reinstalled the Denso plugs and my mileage went back up to what it was before the change! I don't know that it was the plugs, but BOTH sets were gapped correctly, and installed correctly, but the mileage with the NGK plugs was 17-18mpg, and with the Densos...21-21mpg! Go figure!

 

Which 3 were NGK?

 

Driver's side has NGK , passenger side is Denso's from the factory

 

The 3 that aren't Densos.

Well, ok, that.

 

Im sure this has been discussed somewhere else, but while I'm here.....
Why in the heck did they use two different kinds of plugs on each side of these engines???

 

Did you put in copper plugs or irridium?

 

Fake spark plugs

 

Exactly...I laugh when I hear someone say ‘pre-gapped’. I’ve changed my plugs 3 times and bought plugs from the dealer. Never were the plugs ‘pre-gapped’ correctly.