Sudden drop in gas mileage... Afraid something might be wrong

[jnance50]

I don't want to start a mpg gripe thread, I'm genuinely concerned something might be wrong. I'll start by saying that I reset my mpg everytime I fill up and generally see 18-19 mpg on the highway. I have 13k miles on my truck.

So I'm driving home for the holidays Boston -> Alabama. All the way to Jersey I was getting my usual 18-19 mpg. I stopped and filled up in Jersey and when I got back on the highway was only seeing 14 mpg!

I'm now in Virginia and have filled up again since and now I'm seeing 13.5! I did this same trip maybe 6 months ago and I averaged 18-19 the whole way.

I've done everything - I stopped and up my tire pressure slightly - I slowed down to 60 even - no matter what I do I can't get over 14mpg

wtf?

 

[Okki]

Couple observations:
1) Double check your actual mileage by dividing the miles between fill-ups by the gallons your filled up with.
2) You're driving through some majorly different landscape going from Boston to Alabama. This can have a pretty good impact on your mileage; especially if you are hauling a lot of stuff (inside, roof, trailer, etc)

Are you smelling gasoline inside the vehicle while driving?
Are you smelling gasoline outside the vehicle while standing still?
Is there a puddle under the vehicle after standing still for a while that is not AC condensation? i.e. the gas tank is on the driver side in the middle of the vehicle.

Hope you figure it out and stay safe!

Okki

 

[4ShoreRunner]

****ty gas in NJ due to Hurricane Sandy?

 

[GrantK]

If you don't have one, pick up a ODB-II scanner like a ScanGauge and see if you are getting any error codes. Make sure it's rated for the 4Runner (including year), ScanGaugeII is. My guess is either a faulty O2 sensor, an injector or the MAF sensor on the tube between the air box and the intake manifold. You can check for a loose wire on the injectors and MAF, it might be an intermittent contact.

Prior to the fill up when things changed did you notice any change in the vehicle's performance or hear anything that might have bounced up off the highway? Something bouncing off the road could have hit the O2 sensor.

 

[ladywolf]

its also mid nov. gas companies are switching to their "winter" blend, which produces crappier gas mileage. Also, look at the roads and road conditions...are you going up and down hill a lot? braking due to idiot drivers?

 

[tjnaples]

gas companies are switching to their "winter" blend, which produces crappier gas mileage.

My Monopoly money is on this. However I'd check tire pressure and make sure you're not accidentally towing a boat. I've filled up in NYC and didn't have it bottom out like that on highway after resetting though that's my around town avg.

 

[mikebontoft]

I don't believe theres anything wrong.

 

[jangoforhire]

...and make sure you're not accidentally towing a boat.

I hate when this happens.

 

[GrantK]

its also mid nov. gas companies are switching to their "winter" blend, which produces crappier gas mileage.

Good catch!!!

 

[aviators]

Same here...I was getting 18-19mpg during the late summer months and now I'm getting 15-16mpg (driving my normal routes).