Decreased MPG
- Thread starter City4Runner
- Start date
darkandshiny
New member
If you think it is a bad thermostat a new one will only run you about 35 bucks.
2010 TOYOTA 4RUNNER TRAIL Thermostat Housing / Water Outlet
I'm VERY interested in how this turns out. Thanks for keeping us in the loop.
2010 TOYOTA 4RUNNER TRAIL Thermostat Housing / Water Outlet
I'm VERY interested in how this turns out. Thanks for keeping us in the loop.
City4Runner
New member
I might try that water thermostat idea. The price is not bad. Any idea where abouts and how hard it would be to trade that thing out?
Using the cruise control and setting it 5mph over the speed limit is how i get to work. I do a round trip of 34 miles. Approx 28 miles is highway. I thought maybe i was running her a little ruff but The last two tanks i have been non aggressively driving and keeping in mind fuel economy.
Using the cruise control and setting it 5mph over the speed limit is how i get to work. I do a round trip of 34 miles. Approx 28 miles is highway. I thought maybe i was running her a little ruff but The last two tanks i have been non aggressively driving and keeping in mind fuel economy.
Ditto!
kmiller8821
New member
I first noticed this a month or so ago. I attributed it to the changing over of the gas blends to the 'summer blend'. Also, I'm now running my A/C nearly all the time, because at 7am its already 80+ degrees in Texas. I used to get at least "400 miles" per fill up, I'm averaging about 385 now. I need to check my tire pressure, but I've also seen it drop down to 17-19mpg. (I have almost 19k miles on mine)
homeyclaus
New member
I just read that thread. The symptoms are straight forward, but require a mechanic's skill to diagnose and not just a scan tool. The issue I have with this theory is that if affects FJ's in the 40 - 60,000 mile range. Our 4R's are under 25,000 miles.
Symptom summary is:
- wet plugs, black residue (i.e. running rich)
- soot in the exhaust (which mine most definitely has)
- Scan tool showing a high variance in engine temperature in varying conditions
Fair enough, and worth checking, along with the "don't expect any help or understanding from the dealerships" although that's expected from people who'll use an impact wrench on locking lug nuts.
1engineer
Moderator
Most people assume that a decrease in gas milage has to be caused by a mechanical or electrical malfunction. The OP states that he has had a decrease of about 10% in fuel consumption. The first questions to ask are:
Any different driving habits
Tire pressure
Different filling station
Added any additional load(s) to the vehicle recently
Calculation method
Vehicle Mods
Seasonal weather changes (longer idles for heat, air conditioning running full, etc)
Chances are one (or more) of these things happened and he has observed a 10% decrease in milage. If NONE of these things have happened, he could have a mechanical or electricial problem except he is not throwing a code, which takes us back to the operator checklist listed above. Are there instances where it could be a vehicle problem and not throwing a code? Sure but chances are real slim. Check the list first and then report back. Everyone seems to forget that extra cooler added to the back or a teenager listening to music and idling for a few hours out in the driveway or hauling 4 people to the lake or mall or tires being at 27 psi instead of 35 psi or filling up at a different station that uses a full 10% ethanol or the wife driving it for a week or....
My point is all this adds up and it is really hard to have the exact same driving habits and loading conditions and weather week in and week out. There is always an anomaly that happens and most of us forget it. If you are SURE nothing changed then try some of the esoteric troublshooting but until then check the list above.
Any different driving habits
Tire pressure
Different filling station
Added any additional load(s) to the vehicle recently
Calculation method
Vehicle Mods
Seasonal weather changes (longer idles for heat, air conditioning running full, etc)
Chances are one (or more) of these things happened and he has observed a 10% decrease in milage. If NONE of these things have happened, he could have a mechanical or electricial problem except he is not throwing a code, which takes us back to the operator checklist listed above. Are there instances where it could be a vehicle problem and not throwing a code? Sure but chances are real slim. Check the list first and then report back. Everyone seems to forget that extra cooler added to the back or a teenager listening to music and idling for a few hours out in the driveway or hauling 4 people to the lake or mall or tires being at 27 psi instead of 35 psi or filling up at a different station that uses a full 10% ethanol or the wife driving it for a week or....
My point is all this adds up and it is really hard to have the exact same driving habits and loading conditions and weather week in and week out. There is always an anomaly that happens and most of us forget it. If you are SURE nothing changed then try some of the esoteric troublshooting but until then check the list above.
homeyclaus
New member
1engineer,
The issue alluded to with the FJ cruisers dealt with posters who measured this on a mainly highway drive to work, using cruise control. This would imply that there is little variance in the driving habits. Those users experienced a ~20% mileage drop with no additional mods to the vehicle.
Yes, the effects of the most gas mileage drop causes are cumulative, so seeing a 15% reduction from a combination of low tire pressure, a dirty air filter, and a relatively minor alignment issue.
What I understand in the OP's case is that the drop in mileage was SUDDEN with no driveability problems.
My TE with 8500 miles on it also suddenly felt like it was dragging a boat anchor, and yes, the parking brake is off. Mine has also dropped from 20.5 mpg to 17.3 mpg as measured between full-clicks from gas at the same pump at the same station. Toyota's response is a predictable "it's within the normal range, there is nothing I can do for you." Yes, normal for city, not on a flat highway. Again, no mods were done during that time.
Yes, it's possible that on a flat highway something knocked my alignment out, let air out of the tires between my weekly checks (and refills just before I check it again!) and clogged my air filter. Suddenly. Probability? Pretty low.
The issue alluded to with the FJ cruisers dealt with posters who measured this on a mainly highway drive to work, using cruise control. This would imply that there is little variance in the driving habits. Those users experienced a ~20% mileage drop with no additional mods to the vehicle.
Yes, the effects of the most gas mileage drop causes are cumulative, so seeing a 15% reduction from a combination of low tire pressure, a dirty air filter, and a relatively minor alignment issue.
What I understand in the OP's case is that the drop in mileage was SUDDEN with no driveability problems.
My TE with 8500 miles on it also suddenly felt like it was dragging a boat anchor, and yes, the parking brake is off. Mine has also dropped from 20.5 mpg to 17.3 mpg as measured between full-clicks from gas at the same pump at the same station. Toyota's response is a predictable "it's within the normal range, there is nothing I can do for you." Yes, normal for city, not on a flat highway. Again, no mods were done during that time.
Yes, it's possible that on a flat highway something knocked my alignment out, let air out of the tires between my weekly checks (and refills just before I check it again!) and clogged my air filter. Suddenly. Probability? Pretty low.
1engineer
Moderator
My point was most people forget about those most common things that decrease milage. Your case sounds different entirely and judging by your previous posts you are well versed in troublshooting as well as many posters on this board. The OP has 6 posts so not a lot can be gleaned from his experience, hence the reposting of "common places you lose fuel efficiency." I developed a spreadsheet for a guy one time who had a sudden loss of almost 30% fuel efficiency. This helped him to understand his truck's trends and when he made a change you could tell pretty quickly if it was helping or not. PM me if you are interested in something like this.
homeyclaus
New member
Totally agreed.
Ripping stuff open should only happen when other avenues are exhausted. No codes does not necessarily mean no problems, no matter than the Toyota service weasel says.
What was the final determination (s) as to cause of the above listed findings?
in my case I agree with mgrande, when I first got the truck I drove it a lot easier than I do now and now that the summer months are here the truck does more idling, like when I run in somewhere for a couple minutes to get something and leave the wife and baby in the car with the A/C on. Also since it has warmed up we have a lot more road construction going on which results in a lot more idle time in traffic.
homeyclaus
New member
Thermostat opening early/sticking open was the diagnosis. The engine would never warm up all the way for the ECU to get out of warm-up mode.
Keep in mind this was on a 60k mile FJ Cruiser, Toyota would not/could not diagnose, and that owner has already done several iterations of the list of the "usual suspects" that cause mileage issues. Another poster brought that thread in the FJ forum up as the symptoms matching some of the symptoms the OP was complaining about.
Unless it's filled with 20W50 it won't matter to this extent. 5W20 (synthetic or not) is approved for application where the ambient temperature does not fall below 20 degrees F. The "0" or the "5" is the cold viscosity, it has little to no bearing on mileage at operating temperature.
You can read up on all that to your heart's content at www.bobistheoilguy.com.
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natevans65
New member
I have 145K miles on the V8 Sport and at every oil change I run a bottle of Amsoil fuel additive to a tank of fuel and have had good steady success with mileage on my V-8. Here is a link to it....good reading.
AMSOIL - P.i. Performance Improver (API)
AMSOIL - P.i. Performance Improver (API)
114run
New member
Although I am new to this forum, I have participated in many "motor" forums (corvetteforum.com, bobstheoilguy.com, etc.) over the last 15 years. That said, the advice on this thread is some of the best advice/reading I've come across. I'd recommend that this thread be elevated to "sticky" status.
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JohnsD90
New member
lol, summer blend if you guys even have it down in texas, will only increase fuel economy.
homeyclaus
New member
word.
Any thread advocating oil additives should automatically be disqualified from sticky status IMHO. If you talk with the additive package hackers/engineers/chemists over at Bob's you'll discover that compatibility issues abound between 3rd party oil additive packages and the additive packages that oils come with. The best possible outcome is that you'll turn your 'yota's 0W20 to 10W40, but you'll be lucky if worse does not happen. And that's almost the only thing the good folks over there do agree on, since everything else seems to degrade into a discussion of film shear strength vs some other statistic given enough time.
114run
New member
homeyclaus........Good point.
When I first got my 4Runner, I turned the ECO light off and my gas mileage went in the tank. Recently, I turned the light back on and try to drive in the ECO range. By staying in the ECO range, my MPG average (70 highway / 30 city) has been around 22.
When I first got my 4Runner, I turned the ECO light off and my gas mileage went in the tank. Recently, I turned the light back on and try to drive in the ECO range. By staying in the ECO range, my MPG average (70 highway / 30 city) has been around 22.
