Mpg loss after spark plug change
04-19-2019, 09:00 PM
#1
Mpg loss after spark plug change
I know there's tons of posts on this as I've already done Google searches but I figured I'd ask about my specific situation.
2013 FX4 EcoBoost stock, no lift or level, 66k miles, 285/65/18 Duratracs (which dropped the mpg by about 1mpg).
I just replace my plugs myself about 2 weeks ago. Went with the recommended motorcraft plugs, checked the gap, and seemed to do everything by the book. I did not replace the boots or use dielectric grease.
Anyway, my mpg before was at 14.5. I was hoping it would at the very least go up .1 or .2 but instead it has gone down .1 to 14.4. Doesn't seem like a drastic change but it hasn't changed from 14.5 in about a year, so for it to go down after the plug change concerns me. I didn't have misfires or any rough idling before and don't have it now. It seems to run smooth otherwise. Do I need to be concerned or just go with it? I've read that trying a KAM reset is possible but if i had my battery disconnected during the plug change doesnt that reset it?
Thanks for any help.
2013 FX4 EcoBoost stock, no lift or level, 66k miles, 285/65/18 Duratracs (which dropped the mpg by about 1mpg).
I just replace my plugs myself about 2 weeks ago. Went with the recommended motorcraft plugs, checked the gap, and seemed to do everything by the book. I did not replace the boots or use dielectric grease.
Anyway, my mpg before was at 14.5. I was hoping it would at the very least go up .1 or .2 but instead it has gone down .1 to 14.4. Doesn't seem like a drastic change but it hasn't changed from 14.5 in about a year, so for it to go down after the plug change concerns me. I didn't have misfires or any rough idling before and don't have it now. It seems to run smooth otherwise. Do I need to be concerned or just go with it? I've read that trying a KAM reset is possible but if i had my battery disconnected during the plug change doesnt that reset it?
Thanks for any help.
04-20-2019, 12:07 AM
#2
Senior Member
You know, on forums frequented by women, they get uptight about gaining 2 pounds.
Similar.
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13XLTEco (04-23-2019)
04-21-2019, 09:36 AM
#4
King Hater
.1 is such a small amount that could be anything. Headwind, throttle usage, fuel type, etc etc. If you said it went down by 3, 4, or 5+ then we would have an issue.
04-23-2019, 01:13 AM
#7
Trending Topics
04-23-2019, 08:41 AM
#9
Did you happen to check the gap on the plugs you removed?
I've read speculation that a wider than recommended gap is actually better for fuel economy, and that the factory gaps is to help with cold starts and keep an engine running under any condition. If your engine is well tuned and you don't regularly drive with the pedal to the floor, opening up the gap a little may help fuel economy.
If you're concerned, measure the gap in your old plugs, take out the new plugs and then split the difference. Honestly though, 0.1 mpg is nothing to worry about. I calculate my fuel economy every tank and with my regular commute it varies within about 0.5 mpg. There's so many variables that affect this, gasoline quality, air temperature, traffic conditions, etc, that chasing such a small amount is futile IMO.
I've read speculation that a wider than recommended gap is actually better for fuel economy, and that the factory gaps is to help with cold starts and keep an engine running under any condition. If your engine is well tuned and you don't regularly drive with the pedal to the floor, opening up the gap a little may help fuel economy.
If you're concerned, measure the gap in your old plugs, take out the new plugs and then split the difference. Honestly though, 0.1 mpg is nothing to worry about. I calculate my fuel economy every tank and with my regular commute it varies within about 0.5 mpg. There's so many variables that affect this, gasoline quality, air temperature, traffic conditions, etc, that chasing such a small amount is futile IMO.