GenVibe - Community for Pontiac Vibe Enthusiasts

This winter I changed the spark plugs on my Vibe. I installeed Autolite platinums. I noticed that my summer time fuel economy has dropped from an average of 34 mpg to 32 mpg. Could this be because of the spark plugs, or does the 160,000 miles on the odometer have more to do with drop?

All I can say is that different engines react to different spark plugs, and brands of spark plugs differently.While pretty much considered crap now, I used to use Champions, but not all of my cars liked them so I had to change to something else.I am asking the same question for my Mazda. Do I go back to using the tried and true NGK's or try something else. Plugs are no longer For you, I would guess NGK's or Nippondenso's might be the better choices, but the Iridium ones would probably work better than the platinum.For my Mazda, I am looking into E3's, Pulstar's and Splitfire's as well, though I've pretty much eliminated that one, to see what affect they will have.Could easily run over $50 for a set of 4... and they used to be like 0.89 cents ea.

Perhaps with the new plugs, your driving the car with a little more enthusiasm....

I'm going to join in and say to the replace your plugs with NGK / Nippendenso original grade iridiums.I know you'll spend some $$'s but you'll probably notice a difference. As mentioned, different cars like different plugs for some unknown and unexplainable reason.I'm only at 70,000 and thinking of putting in new plugs. Just because. I'll for sure use the iridiums as recommended.My 2x anyway.

...I'd be more inclined to think your drop in fuel economy was due to "winter" fuel versus "summer" fuel...there's typically a change due to differing vapor-pressure requirements between the two seasons.

Quote, originally posted by Old Tele man »...I'd be more inclined to think your drop in fuel economy was due to "winter" fuel versus "summer" fuel...there's typically a change due to differing vapor-pressure requirements between the two seasons.Yes, but its been my experience that mileage improves w/summer gas vs. winter. Winter mix gas usually contains a higher ethanol content to combat condensation, but ethanol as w/all alcohols carries with it it's own O2 molecule. Compared to running regular pump gas and pure methanol, the efficiency drops by 1/3. More fuel must pass through the system to compensate for that extra O2, which is not brought into the intake, but by the volume of the fuel itself, and of course by itself (the O2, I mean) does not burn or add power only aids in the combustion w/the proper mixture.

I am comparing my milage to last summer and I did better last summer. I also noticed that I seem to get better milage as the temperature go up. My car actually seems to like it better when it's over 90 degrees outside. I keep my a/c cranked up, too. So what's the deal with iridium plugs? Do they burn hotter than platinums?

...actually, it's the fact that the metal, iridium, doesn't react (rust, corrode, etc.) with any of the combustion by-products, so they LAST almost forever (100K+ miles usually)....however, iridium metal is both EXPENSIVE and BRITTLE, so only a VERY small "nub" (that extends past the insulator material) is spot welded onto the spark plug core...and it can be VERY easily broken off when you're messing around trying to adjust the gap. That's *why* most iridium plugs come "pre-gapped" to factory specs right from the box....the best analogy to describe spark plugs and performance/economy is this: "...they're like the TOP of a mountain, about as GOOD as it gets at first, and only DOWN HILL from there as they wear/get old."

I asked my uncle (toyota dealer mechanic) about getting NGK Iridiums and he said, "hold off and let me get you some plugs that came stock in your car."He brought em home the next day, but we haven't put them in yet. I'll let ya know how those do, tho I expect to see no real difference except maybe they'll last forever

I was thinking about trying a multi-electrode spark plug, like the E3 or double tip Bosch.

The gaps were good.