Sudden loss of gas mileage - Toyota 4Runner Forum

oncewaspfd · 12-16-2019, 05:15 PM

I got tired of seeing the check engine light on in my 02 4runner. Had a smoke test done and I replaced the charcoal evap canister. I went from 16 mph down to 13 mph. What gives?

MStudt · 12-16-2019, 06:10 PM

The problem is winter. It's well documented that our 4runner's mpg suffer in the cold months due to fuel mixtures.

Mike

T4Rchadly · 12-16-2019, 06:29 PM

dang is that what it is? i was getting nearly 270 miles to a tank only highway driving this summer/later fall and i noticed i can only get 200 after i changed out my RTT to my rocket box for ski season now that winter hit. i was getting suspicous about it as my truck runs and drives like its brand new as ive replace almost every component with OEM parts.

STI_MECE · 12-16-2019, 06:38 PM

Quote:

Originally Posted by MStudt

The problem is winter. It's well documented that our 4runner's mpg suffer in the cold months.

Mike

That makes me scratch my head. Cooler air is denser.....

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T4Rchadly · 12-16-2019, 06:44 PM

Quote:

Originally Posted by STI_MECE

That makes me scratch my head. Cooler air is denser.....

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thats what i was thinking.. im aware that states use a different blend gas during the winter time also though.

MStudt · 12-16-2019, 07:02 PM

Quote:

Originally Posted by T4Rchadly

im aware that states use a different blend gas during the winter time also though.

This is the exact reason for the loss of mpg. Plenty of links here with the same out come. I had the same issue while living in Missouri. Once November came around my mileage went to sh*t until around March, and this happened each of the 4 years of living there with my 4runner.

Mike

JMat · 12-16-2019, 07:05 PM

Quote:

Originally Posted by MStudt

The problem is winter. It's well documented that our 4runner's mpg suffer in the cold months.

These trucks run in open loop a lot longer in cold weather areas not to mention many let them idle to warm up before they jump in in the morning.

MStudt · 12-16-2019, 07:19 PM

Quote:

Originally Posted by MStudt

The problem is winter. It's well documented that our 4runner's mpg suffer in the cold months due to fuel mixtures.

Mike

Quote:

Originally Posted by JMat

These trucks run in open loop a lot longer in cold weather areas not to mention many let them idle to warm up before they jump in in the morning.

You can let you 4runner warm up for 12 hours, and it's not going to change the mixture of the fuel you bought. Do a search, and you'll find these exact same results.

Mike

oncewaspfd · 12-16-2019, 07:52 PM

Thanks everyone. I thought I screwed something up when I installed it.

MStudt · 12-17-2019, 11:21 AM

Quote:

Originally Posted by oncewaspfd

Thanks everyone. I thought I screwed something up when I installed it.

It would have been very difficult to install a charcoal canister wrong on an 02 due to the hose lengths. After the original being installed for nearly 20 years the hoses aren't going to be flexible enough to reach another inlet/outlet on the canister.

Mike

Bad Luck · 12-17-2019, 12:09 PM

Like MStudt said, fuel mixtures change for winter. Combine that with your engine taking longer to reach operating temp and closed loop and gas mileage suffers. Cooler air is a plus, but all the anti-gelling additives they put in gas is a much bigger minus. If you think that your gas didn't change because you live somewhere warmish during the winter then please know that it did. It doesn't have as much additives as the great white north, but they're still present.

mesooohoppy · 12-17-2019, 12:16 PM

oh wow, this is a great thread. in the past, i have alway put 91 in my cars as that is what they called for. when i bought my 4runner that is what i used, just out of habit. when i lifted it and put 33s on it a couple of months ago (near the end of summer). i saw i was getting terrible mileage and just chalked it up to being the heavy SCS wheels and tires. my buddy told me to try out 87 and so far it seems like its been longer between fill ups. i will have to actually fill the tank up and do the math.

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