Worse fuel economy when hot?

[adventureboss]

Does anyone else's gas mileage seem to drop a little when it's hot outside? Mine definitely seems to. I've also noticed the Jeep is slow as hell when it's hot. I feel like I have to bury the gas to get anywhere because the damn fan clutch stays engaged until like 4k rpms. At night when its colder I get 15-17 mpg at 80 mph on the highway and I lose maybe 2 during the day because of the heat here in Phoenix. It's a little annoying pulling away from lights because it feels so sluggish and I have to rev the crap out of the motor (3k-3.5k rpm) to get up to speed when the fan is engaged. People of course get frustrated because I'm accelerating too slow for them. Don't have this issue during the cooler months.

Does this sound normal or do I have an overly aggressive fan clutch? I haven't had another vehicle with a mechanical fan.

Also wanted to add that I replaced the original fan clutch about 90k miles ago with a Hayden 2771.

 

[andyj]

TJs don't accelerate as fast as other cars. Relax mate.

 

[KennethS]

Been driving this TJ since 2002 and I haven’t noticed any difference between the cold months and the 110+ months, so I say yes, you have an issue somewhere.

 

[adventureboss]

TJs don't accelerate as fast as other cars. Relax mate.

I’m aware of that, its just people behind me get mad.

 

[macleanflood]

I'd be logging live ODB data and trying to correlate data points with ambient and vehicle temperatures.

-Mac

 

[JKP]

Fan clutch and AC suck HP.

If in traffic, the air intake is taking in hot under hood air, which is less dense, which reduces HP.

And you only had 190 to start with.

If your fan clutch is starting to seize up, this will make it worse. If it seizes and becomes direct drive, it will be a total dog and roar all the time.

 

[Duck Doctor]

Perhaps are you using the air conditioner during hot months and not during the winter?

 

[Unique Username]

I have worse fuel in the summer. I haven’t considered as to why but both the hybrid and my Jeep get worse in the summer. Car drops from 42 to 36 once it’s over 100-105 and the Jeep is always bad but gets 13-14 winter and 10-11 in the summer. Can’t imagine it’s the AC but I suppose it could be.

 

[NashvilleTJ]

TJs don't accelerate as fast as other cars. Relax mate.

Well, depends on the TJ…

 

[Jayhawk851]

Any vehicle will have worse fuel economy when it’s hot out vs when it’s cold. Running ac, under hood temps, and colder air is more dense.

 

[KennethS]

I have worse fuel in the summer. I haven’t considered as to why but both the hybrid and my Jeep get worse in the summer. Car drops from 42 to 36 once it’s over 100-105 and the Jeep is always bad but gets 13-14 winter and 10-11 in the summer. Can’t imagine it’s the AC but I suppose it could be.

Could be the difference between summer blend fuel and winter blend fuel.

 

[Unique Username]

Could be the difference between summer blend fuel and winter blend fuel.

Could very well be. We add tons of additive to our winter blend in the tanks at work and almost nothing in comparison to the summer fuels. But that is diesel, I don't mess with gas. I never questioned why. Just assumed the combination of high intake temps, Air conditioning and my need to keep my foot in the pedal at times was the contributor.