A/C on, Gas Mileage off

Has anyone seen a significant gas mileage difference in running with the A/C on. I am talking about a 100 mile difference in a full fill up.

Normally I get about 380-400 miles on a fill up, driving 50/50 city/highway. Sacramento gets pretty hot in the summer, so when I am running my A/C. I don't see anything better than 280-300 in a fill up. It is obvious the compressor runs off the motor and will affect mileage, but this much?

 

I notice no difference when running the A/C.

I don’t see why running the A/C would effect mileage at all. Yeah the compressor runs but... it really doesn’t require more engine work to do so

Do you keep up with changing your air filters and spark plugs?

If this is new it may be a sensor that is off.

 

That what I thought, I have never seen running A/C affect gas mileage so much. I just bought the truck a few months ago. I will be doing plug, filters, and all the fluid changes in the next 2 weeks (diff, tranny, etc). So I will see if that makes a difference. Might try and service the A/C system as well. Make sure it isn't low.

 

Remember when...the a/c button was also the speed boost button? Need better acceleration on the freeway on ramp? Turn the a/c off!

 

Honestly man, this is the most sluggish truck I've driven and I am ok with it. I've had my fare share of STI's, V8's, and Diesels, so a/c boost was never an issue ahahah

 

If it’s low... it means you have a leak somewhere so make sure you get that resolved (if thats the case).

I know some people have recommended cleaning the MAF sensor.


You just bought the truck, did you drive it a great distance home or did you buy locally?
When I moved from CO to the midwest my fuel economy dropped in my F250 to 8mpg. It was like I could see the gauge drop as I drove.
I unplugged my battery to reset my O2 meter. Cured the problem and I went back up to a whopping 14mpgs.
Not sure if these trucks have similar issues or not.

 

That's actually a great question! I did, I bought the truck in North Dakota and drove it back to California. I know that plays a big part in boosted vehicles, because I would have this issue on my STI. It just didn't like elevation if it was tuned at sea level. Which happened quite a bit when I drove up to the mountains. I'll give it a shot though, and try cleaning the MAF, do people still just use electro wash to clean those?

 

AC is a belt driven compressior on a clutch iirc. If it is, engaging it will result in a parasitic power loss ie. You'll have to apply more throttle to compensate for the power "taken" to drive the compressior and quite likely higher fuel use. I like to refer to AC as the"engine brake" in this truck

 

You live in California. Welcome to the land of shitty gas. Additives designed to reduce emissions result in reduced fuel economy. Never mind that running the AC does impact performance to a degree.

100 miles per tank seems excessive. Lifted with 4x4 and 34’s, I see about 20-40 mile reduction with summer gas. Depends on how I drive.

 

I like California, for the environment and the outdoors, but that's about it. I do agree on the shitty gas, depends on where you fill up, you can definitely see a difference in the MPG's. Sounds like something is definitely wrong though.

 

I don’t think so.

I averaged about 290-310 total miles a tank in my 2.7 and I live 2 hrs from you. All year round.

I think you’re just not accustomed to our gas efficiency.

 

The AC compressor does indeed require engine power. That's why the AC button (turned off) equals "power boost" LOL. But even with the AC constantly running, it should only decrease 1-2 MPG at the most. So if you can prove the AC is the actual cause of your MPG decrease, there is indeed a problem. Your compressor may be dragging? That may sound dumb but I don't know enough about these specific AC systems to pose a more intelligent guess. I just know that the compressors do require a certain amount of power when the AC is on, and the compressor cycles on/off periodically during constant use.
Also, yes these trucks are pretty gutless unless you rev it high. They are built more for durability than for performance.
I live in Sacramento and it does get hot, but I only use the AC as needed. I guess I have a wide tolerance for temperature. I average 24-25 MPG in summer and 21-22 in winter.

 

Ill be doing some maintenance here in the next few days. Try all the recommendations, and see what happens! Thanks guys!

 

Yes, my 2.7 MPG drops about 1-2 during the summer months here in Texas. But i dont think that equates to 100 miles per tank (i not good at the math).

 

I started driving 4cyl Toyotas in 1971. My 71 was a two speed automatic trans. Talk about sluggish. I remember when I turned on the A/C in those early Toyotas it was like you threw an anchor out the window. You noticeably felt the deceleration.