Gas mileage just went for a S#!T

[ONTHEPIPE]

2 months ago I was getting just over 500km to a tank, not great but I was ok with that.

Lately I've noticed I'm filling the tank more often so I let the old fuel light come on then hit the gas station and reset the trip... And here's where I'm at

63 liters to fill
146.7 km at half a tank

Looks like I'm on my way to 300km to a tank I'm gonna change air filter today just because.....although it doesn't look bad.

I'd love some ideas PLEASE

Oh I also have an evap minor leak code..... But I've had it for a long time

 

[ONTHEPIPE]

K I just checked for more codes and still only have the evap code PO 0442

 

[HoosierJeeper]

Winter blended gas perhaps?

 

[ONTHEPIPE]

Frig I hope not . does your fuel go for a crisp every winter?

 

[HoosierJeeper]

It does a bit. Usually by an MPG or two.

 

[Dave]

Mine drops a couple of mpg with winter gas. Do you get "winter gas" in Canada?

That 0442 code might be a poor sealing gas cap.

Dave

 

[Cardhu]

I get about 300 a tank on 100% "city"driving. sometimes less given 20 min of idling per day atleast.

Its abysmal but wintergas plus -30 this week isn't helping the efficency.

 

[WickedBruce]

I had a groundhog in my engine and got an evap code after he chewed a bunch of stuff...ended up getting new pigtials and some scotch loks from the dealer for the evap purge solenoid and it fixed it. was getting -5 mpg. lol

 

[Luke]

My KJ is so freekin weird ... my gas mileage actually improves in cold weather. I would start with the usual tune up stuff .. plugs filter clean throttle body IAC etc. etc.

 

[Dave]

Forgot to mention before, check/change your PCV valve. They are cheap and might affect mpg if clogged.

Dave

 

[ONTHEPIPE]

Just got in from changing air filter and plugs. I also dumped in a jug of injector cleaner and topped off the fuel tank. See what that does, next I'm thinking fuel filter.....really I shoulda got one while I was in town but never thought of it till I was home. I'll get a PVC valve too Dave, good call.

Is there anyway to see if my gas cap has crapped out without buying a new one to try?

Thx for all the input everyone!!!!

 

[hectikart]

I'm sure you're on top of it, but is the oil due? I was getting 18/19mpg when I was due for an oil change (I run full synthetic, changed every 7500 or earlier if dirty). After changing the oil my mpg immediately shot up to 22/23mpg. I was really surprised it made that big of a difference.

 

[ONTHEPIPE]

Changed it around 2000km ago. But I don't use synthetic oil. do you find it's worth it?

 

[tjkj2002]

Colder weather always means worse mpg's as you stay in open loop longer and most places use different gas blend in the winter months for emission reasons which drops mpg's.


Depending on the year a new fuel filter can help alot,they deleted the serviceable fuel filter in '05+ I believe.


Be thankfull I get 70 miles to the half a tank,then again all city driving uphill.

 

[Luke]

Maybe my warm garage + colder intake air = slightly better mileage? :shrug:

 

[Luke]

Changed it around 2000km ago. But I don't use synthetic oil. do you find it's worth it?

Maybe it's my synthetic oil?

 

[hectikart]

Changed it around 2000km ago. But I don't use synthetic oil. do you find it's worth it?

I like synthetic because it doesn't break down with heat like conventional oil. That's why you can go twice as long+ on one oil change. Really just needs to be changed when dirty. Price wise it's basically a wash...oil is twice as much, but you buy it half as often. I guess you save money buying half as many filters. Some people still change the filter around 3000 between synthetic oil changes, but I don't think it's necessary if you use a good quality filter and check the condition of the oil regularly.

I agree about the winter months = less mpg too. Always seems to be that way.

 

[DocHemi]

I like synthetic because it doesn't break down with heat like conventional oil. That's why you can go twice as long+ on one oil change. Really just needs to be changed when dirty. Price wise it's basically a wash...oil is twice as much, but you buy it half as often. I guess you save money buying half as many filters. Some people still change the filter around 3000 between synthetic oil changes, but I don't think it's necessary if you use a good quality filter and check the condition of the oil regularly.

I agree about the winter months = less mpg too. Always seems to be that way.

I run synthetics in everything, might be because i sell them as well hehe, but i think they have many benifits over dyno oil.

We run full syn, and special 15,000 mile filters and have no problems.

I gotta ask ya tho...mileage above 20mpg in a KJ....is that all highway? what gears do you have? The best I ever got was highway mileage of 21 and that was doing only 55-60mph....if i think of touching the accelerator it goes to my usual high 17's

 

[hectikart]

I run synthetics in everything, might be because i sell them as well hehe, but i think they have many benifits over dyno oil.

We run full syn, and special 15,000 mile filters and have no problems.

I gotta ask ya tho...mileage above 20mpg in a KJ....is that all highway? what gears do you have? The best I ever got was highway mileage of 21 and that was doing only 55-60mph....if i think of touching the accelerator it goes to my usual high 17's

It was all highway driving, stock gears. My normal everyday city/highway mix usually gets me about 18/19 mpg. When I lived in Boston, I was getting 16/17. This time I calculated the mileage over a 650mi highway trip. I didn't have time to do the oil before I left, and was getting about 18/19. Changed it while I was away before returning home and managed 22/23. I actually find I get better mileage at a constant 70-75mph. That's what I was doing the whole way home. I will say there is definitely a lot of variance between driving style and conditions though.

 

[eradicator006]

2 months ago I was getting just over 500km to a tank, not great but I was ok with that.

Lately I've noticed I'm filling the tank more often so I let the old fuel light come on then hit the gas station and reset the trip... And here's where I'm at

63 liters to fill
146.7 km at half a tank

Looks like I'm on my way to 300km to a tank I'm gonna change air filter today just because.....although it doesn't look bad.

I'd love some ideas PLEASE

Oh I also have an evap minor leak code..... But I've had it for a long time

That's close to what I get for fuel mileage in the winter. When it's around -30 I'm lucky to get 280km per tank (all city). I run full synthetic 0w30. I'm sure the drop in mileage is from the winter blend gas. Once spring rolls around I'm back to high 400's (all city) per tank.