Changed spark plus mpg down

Goatman91 · Feb 22, 2015

I changed my spark plugs back in late November and saw a decrease in Fuel mileage. WTH. I'm averaging 300 milled on 26 gals mixed driving which is 11.5mpg. Not bad but I was getting 400 or almost 400 before. I'm running mobil 1 full synthetic, 89 octane fuel so idk what the heck is going on.

Talon_66 · Feb 22, 2015

November... Well chances are your mpg dropped because you're running winter blend gasoline. More ethanol in it = decreased mpg

jwheeler · Feb 22, 2015

Yep. Winter fuel. What spark plugs did you put in? Properly gapped?

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wheelhopper · Feb 22, 2015

Hope this does not happen to me. I just bought a Ram 2500 with 58K miles and I am pretty sure the plugs have never been changed. I am getting less than 12mpg right now and this is the first gas powered truck I have had in a long time. As soon as it warms up a bit I'll change them out.

atc06jh · Feb 22, 2015

Yea the winter weather will have an affect on everything. If you let your truck warm up in the mornings for a few minutes, that'll take your average down a good bit. Since we have had these cold snaps the past few weeks, I watch my average drop by like .6 every morning while it is warming up. It 'll slowly come back up once I start driving a ways. But warming my motor up properly and not messing anything up is worth losing a little on the MPG end!

BLKSHP · Feb 22, 2015

Did you double check gap before installing? I've had a few plugs be way off even though they were to be pre-gapped.

Goatman91 · Feb 22, 2015

I used Mopar ngk plugs. They said they were pre gapped so stupid me didn't even check. I was wondering about winter fuel, I live in lousiana though, do we have winter blend fuel? It sounds like a ridiculous question I know.

Goatman91 · Feb 22, 2015

Should I use a different plug maybe?

jwheeler · Feb 22, 2015

You will not get a better plug than that. The platinum are pre gapped. If you got the regular copper that it came with, it is not. I always check it. I have seen parts guys drop them on the floor before they hand them out.

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Goatman91 · Feb 22, 2015

Well hell I guess I'll have to pull them out and re gap them.

Changed spark plus mpg down

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