I've always known vehicles to get better gas mileage in warm weather than in cool weather, but mine is the opposite. This past weekend I went for a lengthy drive and realised just how bad it is. On the ride there I used a little over a quarter tank of fuel in roughly 95 degree weather... On the ride back I traveled the same roads in roughly 65 degree weather and used around an eighth of a tank. I also have a SEVERE loss of power in warm weather.

Mods/Parts Replaced: (That Would Effect This)
-Bored Throttle Body
-Cold Air Intake
-2.5" Magnaflow Catback w/ Thrush Highflow Cat
-Freshly Rebuilt 703 Injectors
-New Distributor
-New Cap and Rotor
-New Coil
-New Plugs
-New Wires
-New Cam Sensor
-New Crank Sensor


I'm using the same Pennzoil 10w40 I've always used and the same Shell gas from the same gas station. All of the mods/parts listed above have less than 1,000 miles on them.

Tomorrow is supposed to be around 108..... I'm almost afraid to drive anywhere..... A private Jet would be cheaper.

Can anyone shed some light on why my gas mileage sucks so bad in warm weather?

 

As long as there have been automobiles running the internal combustion engine that loves fresh, cold air in it, there have been people getting poor gas mileage when the weather is hot, humid and the air quality is crappy. In Maine we get some horribly hot & humid weather in the summer, and every summer my mileage goes down. Add to that I use the AC a lot more, and it gets even worse mileage.

 

Well untill you stop trying to track your gas milage with a gadge that can be OFF by as much as a 1/2 tank at any given time. You will never know if you have a problem or not.

 

I've never had a problem with my guage being off. I'm not guaging my gas mileage off of just the guage either. When I get 90-100 miles to a 19 gallon fill up at the pump during a heatwave and 170-190 miles to a 19 gallon fill up on a cooler week..... There's obviously a problem.

 

You will always get better mileage in cold weather, unless your thermostat is trashed.

If you can't be good, be good at it!

 

Wow, so you get 5-6 mpg in the summer? I get 17 city driving

 

I heard in previous forum post's sometimes non dealership replacement parts can cause a decrease in mpg becuase they are usaully 1 size fits all, so if you have a lot of non dealer parts that could be the problem.

 

The only thing I can tell you to check is the O2 sensor as that can drastically change fuel economy.

This past Sunday I got 10mpg driving an hour and a half to the offroad park towing an atv on a trailer and 4 people inside, then wheeling for 6 hours and do the same thing back home with extra mud to weigh me down some more. 173 miles to 17 gallons.

 

x2 Im getting 10 mpg city. F*** that. Im changing the O2 sensor and also the air is so HOT and humid here. I can just tell my little Jeepy hates it sooo mcuh poor girl

 

Here's a shot in the dark... it might be a temp sensor problem. The intake or coolant temp sensor might be reading colder than they should when it's that hot. When they go bad they usually read colder and that will richen things up. MAP sensor might be messed up from the higher operating temps too.

Good luck, bad mileage really sucks!

 

Thanks for the suggestions guys... I will replace my o2 sensor after vacation. Can I test my temp sensors with a meter? I don't want to replace a ton of things that aren't bad.

 

The O2 sensors are good for 100-150K miles..or so I've heard haha

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i put midgrade in my jeep in summer! help about 1-2 mpg.....

 

148k and running EXTREMELY rich..... I think it's time for a new one.

 

https://www.cherokeeforum.com/f2/o2-sensor-97299/

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