Decreased MPG

C

City4Runner

New member
2010 Toyota 4runner SR5 V6

I was just wondering if anybody had any issues of suddenly having decreased MPG. I was averaging between 20-21mpg combined for a tank. Mainly highway I normally travel. A little over 15000 miles I noticed after my service and a fill up I was averaging between 17.7-18.5 for the same commute.

I thought it was bad gas at first so I drove the tank empty (no knocking or rough idles) and filled it up with a gas station I always used. No real improvement. I ran two tanks and same results. Just got it back from the Toyota Dealership (Courtesy Toyota SR 60 Brandon FL) today and they plugged there computer into it and said they could not find any error codes with the vehicle (took 4 hours to find this out).

They now instructed me to run it almost empty and fill it up with 93 octane because it’s possible dirt in the injectors. So I am currently doing this now.

They said if it does not get solved I can bring it back with a full tank and they would do a fuel consumption test on it. Drive approx 100 miles and what else they do I don’t know. If they find something wrong they would take apart parts of the engine (fuel injectors, throttle body, top of engine, sensors) and see if they can find a problem. The issue is that if they don’t find anything wrong with it during the test I would have to pay 100$.

I asked them the details of how they decide if it is a problem or not and they did not give a forthright answer. I go what if you find out its 17mpg highway and the EPA estimated MPG is 17 city that means it passed or would it fail. He would not answer.

Let me know what you think.
 
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Let me get this straight. They want to drive your new truck, that's under warranty, for 100 miles using your gas, and then charge you $100? I would tell them where to go!

Do you honestly think they will find anything wrong during a test drive that the 4 hr(!)computer check didn't find? If there was a problem- it would most likely be computer related, I would think.

Maybe check your tire pressure. Have you reset the avg meter recently?

I think the dealer wants a day trip on your wallet! IMO :)
 
I'm in the same boat

Unfortunately, I'm in the same boat as you

Shortly after my 20,000 mile service I went from an average of 20mpg with the ability to hit 23+ possible at 45mph with the cruise control on to 16-17 average mpg and barely 20 at 45mph.... even after running Chevron Techron through it :bash:

I just filed up with regular and will try what they suggested to you- to run it near empty and fill it up with 93 or 94, but PLEASE keep us updated. I'm sure we're not alone, as I've been on the verge of starting a thread about this several times myself~
 
Tire pressure is a big deal, hopefully they would have said that. Doing any 4x4 offroading will no doubt lower it. Resetting your MPG meter is something to do after each fill up as well. Toyota recommends 87 octane, if you have been putting higher in all along that could be another reason.
 
Did the dealer use any additives, like fuel system cleaner, or an oil additive? I had a Honda some years ago that went from 35 highway to 30 highway after scheduled maintenance and found out the dealer used some new fuel system cleaner (not manufacturer recommended) which I am convinced was the culprit. Of course the dealer denied the cleaner could do it, but what else could it have been?
 
I don't own a 4Runner, might in a few months. Recently looked at buying an FJ and researched that quite a bit, read a lot of their forum info. Turns out they basically have the same problem, and the engines are very similar. Last root cause I read was a weak thermostat, it fully opens early, the engine stays in warm-up mode which eats more gas. This doesn't set a code either.

This may or may not be your issue, but it might be something to think about.

Good Luck!
 
boater3456 said:
I don't own a 4Runner, might in a few months. Recently looked at buying an FJ and researched that quite a bit, read a lot of their forum info. Turns out they basically have the same problem, and the engines are very similar. Last root cause I read was a weak thermostat, it fully opens early, the engine stays in warm-up mode which eats more gas. This doesn't set a code either.

This may or may not be your issue, but it might be something to think about.

Good Luck!
Click to expand...

Good idea.



If I was in your position City4Runner, I would be running away from that dealership. I bet that four hour computer reading cost a good bit. You can go to Advance Auto and have them read codes for free.

I know it's a long shot, but you could try some Sea Foam or maybe another gas additive.

At any rate I would take it to another shop instead of the dealership.
 
Over many years, 25+, I've found it easier, and cheaper, to add a bottle of "fuel-injector" cleaner every 3k miles or so, and have never, ever had fuel-injector problems, or problems you're describing. Now I run a bottle of Chevron Techron in all my vehicles every 3k miles.

My MPGs are acceptable now, and around my area I use ethanol-free gas. For prolonged trips, that will not be possible, and I may suffer a decrease in MPGs myself.

Just sharing a bit of info. :peace:
 
Ya they were a litle low. TPMS was not activated. Since they adjusted the pressure still no change. I figured they probably were just going to rip me off. The last time I will head to this dealer.
 
STLDAVE said:
Did the dealer use any additives, like fuel system cleaner, or an oil additive? I had a Honda some years ago that went from 35 highway to 30 highway after scheduled maintenance and found out the dealer used some new fuel system cleaner (not manufacturer recommended) which I am convinced was the culprit. Of course the dealer denied the cleaner could do it, but what else could it have been?
Click to expand...


The printout they gave me should no changes other than and oil change and tire rotation and top off fluids.

Anybody think if they were to put a non synthetic motor oil in the engine it would cause a sudden decrease of MPG?
 
City4Runner said:
The printout they gave me should no changes other than and oil change and tire rotation and top off fluids.

Anybody think if they were to put a non synthetic motor oil in the engine it would cause a sudden decrease of MPG?
Click to expand...

if they didnt put the 0w in there yes it would. Also the other guy that mentioned you could be running in "open loop" the whole time instead of switching over to closed after the engine warms up. I dont know about fuel injector cleaner causing it, personally I have had good results with lucas fuel treatment. If they reset your computer or disconnected your battery it may cause this problem for a little while as well.
 
14k miles on mine and my fuel economy when new was 19-22 mpg
now its more like 17.2 - 19.6 fwy. I haven't been able to get the
numbers i had when new. Its not lifted but i do have some tires and
wheels on it. 17x9 on 265/70/17 nittos however i noticed the drop
in fuel economy before i got them and the wheel/tire combo is
lighter than the oem set up. I'm wondering what i can do.
 
OK- my tires were all to spec (around 32psi or just under) but lower than I prefer to keep them (at 38psi) so I went and aired up and filled up my tank~

Give me a few days and I'll let you know how much it helps, which I suspect will be a LOT!
 
I might just be for some people when they get a new car they baby it a little, and that will get you really good MPG. As time goes on and you drive it normal you start to see your regular fuel efficiency.
 
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