Another mpg question

[JB_Runner]

I've looked everywhere and still can't seem to find an answer. I herd people saying they get 20 mpg on the high side. And ranging from 16-17 average. I've been getting 13-14 and drive a stock 4runner with stock wheels. I have a new oil filter and changed out my plugs and wires. I'm just trying to figure out why my mpg are horrible. Any input would be nice. Yes I do drive at lot of city but so I wasn't surprised at the 13 mpgs but my last tank I did mostly free ways and still got 13 mpg cruising at 65.

 

[jeff88]

There are so many variables to determine what could cause a low FE.

*What are your tires pumped up to? Did you recently get new ones? New tires will always have higher rolling resistance to old ones with no tread left.

*If you're cruising at 65, you should be seeing higher numbers. Are you driving faster ever? I usually keep the truck under 2500 RPM, even for accelerating, do you ever hit 3 or 4k?

*You could have an issue somewhere that doesn't effect performance, but will hurt FE.

*What about other maintenance items? When's the last time the PCV valve was changed? Air Filter?

*It's been cold here the last few weeks, meaning better performance and worst FE. Is the 13MPG a relatively new number or has it been going on for weeks/months? Don't forget we are on winter fuel now.

*A useful item is getting a ScanGauge or UltraGauage (I have the UG, it's cheaper for the same thing). Not only does it help you determine best driving practices, but it connects to the OBDII port, so it can read trouble codes and pending codes.

 

[Chandlerdoom]

That sucks, I could check your air filter, fuel filter first. Still no change then it will might be your O2 sensor. They can go bad without throwing a light right away

 

[Zulch_AW]

That sucks, I could check your air filter, fuel filter first. Still no change then it will might be your O2 sensor. They can go bad without throwing a light right away

Yea,

MAF also, clean it! Same with throttle body and check your throttle/transmission cables.

What's your idle rpm?

I'd do a complete tune up, as much as my wallet can handle. At least spark plugs and filters as suggested. Proper grade oil as well. Check/replace your thermostat, running cold can effect mileage and if a cold climate maybe not getting up to operating temp quick enough or at all is strictly city driving.

Scan gauge is great but smart phones have cool apps that do most of it, you just need an interface with your OBD but you can get set up for ~$30.

When I first got my 4R it was supposedly recently tuned but far from it. I did as suggested above and went from 17 to 23+ mpg on my first long fwy trip!

Zulch

 

[JB_Runner]

Thanks for all the input.

I mean to say changed out my air filter not oil filter. Also changed my pcv valve right before my last fill up. Also I always have been getting around 13 ever since I picked up the 4runner.

 

[Chandlerdoom]

Thanks for all the input.

I mean to say changed out my air filter not oil filter. Also changed my pcv valve right before my last fill up. Also I always have been getting around 13 ever since I picked up the 4runner.

well since you did your air filter, replace your fuel filter. Its cheap and probably should be done anyways if it doesn't fix the problem. Zulch is right, clean your MAF too, cleaner is cheap.

 

[Robb235]

I had a bad oxygen sensor when I first bought my '99, and it caused very pour fuel mileage. I knew I had a problem because the check engine light was on. I replaced the front oxygen sensor and it brought my fuel mileage up. Your oxygen sensor could be going bad. Not a bad idea to clean the MAF as well.

What is your tire pressure currently set at? What tires are you running? Do you have a stock or aftermarket roof rack? You keep your A/C on? Have you ever Sea Foam'd the? If so, when?

You should definitely be getting way more than 13mpg at 65mph. Heck, I can pull 21mpg or so going that speed.

 

[Swimmerboy2112]

My money is also on the 02 sensors. They're probably in need of replacing anyway.

My 4Runner gets 18-21 with a factory roof rack and supercharger, V6 4x4. 18 is the worst I ever got and that was city driving with liberal amounts of boost.

 

[quicksilvr]

Also, AFTER you do you any work like fuel filter, O2 sensors, and/or MAF cleaning....Pull the fuel pump relay from the fuse box under hood and leave it out for 15 minutes.



Actually, just read this:

Tune Ups!

 

[EatonKyleH]

What year do you have?
And do you have a Federal or California emissions model?

Both make a very significant difference in diagnosing and repairing fuel consumption related complaints.

If you have that info and anything that can read basic scan data (fuel trims, calculated load) such as a scan gauge, smart phone app, etc. we can quickly and accurately diagnose these kind of issues.

 

[UTEP]

And reset computer. Pull EFI fuse, turn key to on and wait 30-60 seconds. Replace fuse. Done

Do this after any major change. Ie doesn't matter after oil change but does after MAF cleaning or spark plugs. Fuel management type changes

 

[OTB]

Also don't forget that we are currently on winter grade gas which means less fuel efficiency.

Currently I am getting 16.5 mpg with mixed driving.


First check the free stuff. Air up your tires a bit and adjust your driving habits.

 

[J. B.]

Also related to O2 sensors....
Your O2 sensor may be good, but you may have an exhaust leak prior to the sensor so the sensor is reading a lean condition and telling the computer to input more fuel than necessary.
Check for exhaust leak.

 

[Robb235]

Also related to O2 sensors....
Your O2 sensor may be good, but you may have an exhaust leak prior to the sensor so the sensor is reading a lean condition and telling the computer to input more fuel than necessary.
Check for exhaust leak.

Piggy-backing off this, you can find an exhaust leak by Seafoaming the intake. I forget which vacuum line to pour the Seafoam in on the 4Runner, but it'll cause the exhaust to smoke really bad. Makes it real easy to find exhaust leaks.

 

[J. B.]

Piggy-backing off this, you can find an exhaust leak by Seafoaming the intake. I forget which vacuum line to pour the Seafoam in on the 4Runner, but it'll cause the exhaust to smoke really bad. Makes it real easy to find exhaust leaks.

I take the vacuum line from the brake booster and put some in there. Hello smoke.

 

[Robb235]

I take the vacuum line from the brake booster and put some in there. Hello smoke.

For some reason I thought you weren't supposed to use the brake booster on these motors, because it wouldn't evenly distribute the Seafoam to the cylinders. Then again, since you're only looking to make it smoke (and not clean the top end of the motor), I guess it doesn't matter.