[Kev2006]

Hi all,

Got my 2006 AT at 198K, put in some new Bosch plugs at that time, think they were Iridiums, anyway I used to get about 30MPG average city/hwy according to the computer. Car is now at around 273K, for the hell of it I replaced them with
Denso (4702) IK20TT from Amazon, now the car gets around 26MPG. I noticed the old plugs had worked themselves a little loose. Otherwise they looked normal, with maybe a slightly larger gap than the new ones I replaced them with. Anyone know why this would happen? I hate wasting premium gas. Car seems just as peppy as before at least.

 

[Litespeed08]

Having used several brands I've found the best performance, for me, came from using NGK Iridium plugs. Did you check the gap as well as making sure that the tips of the new plugs were not loose? Are you using gas from a different station?

FYI, it has been found that there are many counterfeit car parts, including spark plugs, sold on Amazon. Even auto parts vendors have been fooled and unwittingly thought that they were selling genuine parts on Amazon. There are even YouTube videos discussing this. Hopefully you aren't one of the victims.

 

[_Sam]

Had Bosch when I bought mine. Switched to NGK and it improved immediately.

 

[Kev2006]

Hmm. Well, I hadn't really taken into consideration the change of seasons(here in Wisconsin, when we have remote starters, we tend to have our vehicles idling a lot more), and also the fact that I've recently just moved a lot closer to work, so my city driving is much more than it was before vs. highway. Anyways, I drove about 210 mostly highway miles with the new (alleged) Denso plugs today and got 30.5 MPG average, pretty sure that's on par with good mileage for the 1st gen with automatic and driving with a feather throttle. if not, I'm sure someone will let me know. So I think I'm OK with the plugs in there, thanks for the responses.

 

[_Sam]

That sounds good to me.