Significant drop in fuel economy... ideas?

park it til summer. problem solved.

 

The only time I saw 13mpg on my Tacoma was when the third cylinder spark plug was miss-firing. Never got a check engine light either. I say might be worth it to replace the plugs. Since then... lowest I've got is 17.5mpg city. But I still have a "stock" tire/ride height.

Other things I've done to bring me to around 24mpg:
-Clean mass airflow sensor
-Clean throttle body
-Change oils / manual trans fluid / differential fluid
-pump up tires from 26-29psi to 40psi (265/70/R16) [max psi labeled = 44psi]
(cold tire pressure fyi - pre-driving)
-Take the car off defrost or A/C mode
-installed a block heater for upstate NY city commute - keeps the engine around 110F not bad for 20F weather. Keeps the mpg's in check for <5miles drives.

 

http://www.tacomaworld.com/forum/2nd-gen-tacomas/194396-mpg-issues-resolved-enter-here.html

See the thread I started about this, running at and above 2000 RPMs has a huge impact on MPGs, that coupled with your tire pressure could be your issue.

I am currently running my 265/70 17s at about 35 psi.

 

I make gasoline and we are making winter gas. Winter gas has a higher vapor pressure which means it has more light stuff due to the lower ambeint tempature. Gasoline needs to be light enought to vaporize in cooler temps. We have gone from 3lbs vapor pressure to 5lbs vapor pressure on what we make in my units. I have also been making lower octane (80) gasoline because the winter additives bring the octane back up.It is also cheaper to make winter blend. I make three of the produces for the blending. And if you use Propane in your homes for heat I make that too.
http://zhome.com/ZCMnL/PICS/winterGas/winterGas.html
this is a quote from the above web page
The trick is to have the right fuel for the right time of year. In the summer, when the temperature is high, the presence of too many light components will cause the fuel to evaporate too readily. This can result in vapour lock, an over-rich mixture and excessive evaporative emissions. In the winter, too many heavy components keep the fuel from evaporating, causing hard starting, a lean mixture, heavy hydrocarbon emissions and poor converter light-off.

 

This may very well be my issue... at least I'm going to check it off the list. I picked up new plugs and will change them before I leave today. I'll report back on my findings.

I'm checking mileage by resetting my trip mileage each g time and dividing by the gallons I put in each time. Same way I've always done it.

 

The other change I'm seeing is that most gas up here is 10% ethanol. I'm sure that would have some effect, but I'm not sure to what extent.

 

I hope it helps. Tried to give my best experience so far. Only owned the truck a year though.
Maybe check the air filter and other bolts/clamps.

10% ethanol will definitely get you lower mileage, but you still shouldn't be getting 13-15mpg unless your going like 90-110mph. All my results are based off E10. There are no "true" gas stations around me.

 

When is the last time plugs and stuff were done???

 

Plugs 30k ago. Half way done with a plug swap right now.

Differential, engine oil, and air filter were done right before leaving on this trip.

 

Well, plugs seemed to have made a difference. I was fighting some serious head- and crosswinds on the 1000mi trip home, but managed to average around 16mpg. I had a tank that hit 19mpg when the wind left me alone for a few hours last night.

Kinda surprised, honestly. I was right at 30k on the plugs, and they all looked great when I pulled them. Found it interesting that the taco requires 30k plug changes but my father's f150 only required them at 100k.

 

NICE! Glad it worked. & yah 30K is average from what I remember on older cars. But most plugs nowadays advertise 100k plug changes. Hum.

 

Most of the automotive manufacturers that are using the 100,000 mile spark plugs are doing it because of the difficulty in changing plugs in the cramped engine compartments of todays vehicles. The plugs give no better performance, they just last longer. If you can get to your plugs, probably they are 30,000 mile plugs.

 

Check your brakes to make sure they aren't dragging. Check your u-joints for slop and proper greasing. Leave your tailgate up.

Check your wheel bearings for slop too.