I have a 90 4.0 auto and it takes roughly 65 litres to fill, i only get 400km to a tank. 1 km = .62 miles so that means im only getting like 250 miles to a tank? What the .... could be causing this. I got so much new parts and scans its crazy, only thing i havent replaced is exhaust, injectors, and a fuel pump. Suggestions? Could a bunged up muffler do this? Oh yeah i got new at 235/75 15s no lift yet, and no mods(cause there is none for a 90 that i can find) i maintain it very very well.
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Real bad mileage
- Thread starter Lusty
- Start date
Starscream
NAXJA Forum User
- Location
- Columbia, SC
Have you checked your catalytic converter? I know mine was gunked up pretty bad before I replaced it and it was choking power slightly causing mileage drop.Lusty said:
mwm
NAXJA Forum User
- Location
- Nanaimo BC
400km is good dude. I used to get like 360-370 when i was stock with my 90'
RichP
NAXJA Forum User
- Location
- Effort, Pa
With 235's you should be getting around 19-21mpg, check the cat, then dump a few cans of fuel system cleaner thru.
First off I'd do plugs, cap, rotor and wires so you have a base point, then work from there, use copper plugs, the factory Champions as well as factory cap, rotor and wires. Tire pressure too, that does a lot. Also what temp does it run at ? if it never heats up to 190F then it never comes out of cold loop and runs rich which will ruin your cat, etc etc etc..
First off I'd do plugs, cap, rotor and wires so you have a base point, then work from there, use copper plugs, the factory Champions as well as factory cap, rotor and wires. Tire pressure too, that does a lot. Also what temp does it run at ? if it never heats up to 190F then it never comes out of cold loop and runs rich which will ruin your cat, etc etc etc..
- Location
- Atascadero, CA
yeah im gettin extremely bad milage too and my cat is broke because it rattles and the guy at the muffler shop said it was. the filter thingy inside the cat can brake free from the edges of the inside of the cat and rattle around real bad, this can also cause it to flip around and block the exhaust flow from your engine backing everything up. im getting a new cat and flowmaster 40 delta series with mandrel bent tubing put on this should increase gas milage by a small precent and increase horsepower, so im led to believe. hope this helps.
canadianwheeler
NAXJA Forum User
- Location
- canada
mwm said:
I agree. I got about 350 km max on my 92 xj when it was stock.
canadianwheeler
NAXJA Forum User
- Location
- canada
Shomsky462 said:
I got a high flow cat and a 40 series delta flow muffler and after the install i felt a little more power but not much and my MPG stayed the same.
ok i guess i shouldnt complain to much about the mileage from what i see. I dont have a cat on my jeep it must have been cut off, cause its just straight back to the muffler. Ive been very thorough with the tune up aspect of things and check tire pressure on the regular. I just felt that 65 to fill should last more than 400 kms. Any suggestions on a lift...budget lift(i can get quick) ,suspension lift ill have to wait, i dont plan on goin more than 3" (for now atleast)i know my mileage may decrease some after this, i dont wheel much yet, its very flat here compared to B.C. where im from. Thanks everybody
RichP
NAXJA Forum User
- Location
- Effort, Pa
If the cat was removed was the O2 sensor removed also ? Not sure of the result of a removed sensor vs a faulty one, wonder if it could cause a rich conditon. Newer XJ's have two, one on the downpipe and one by the cat, your's should only have one on the downpipe. The engine also likes a bit of back pressure and the cat provides that pretty much. Also check your spedometer, going from stock 215's to 235's throws the spedo gear off in some cases.
When I did the same change on my 98 my spedo was dead on after the tire change which meant it was spinning up milage faster with the smaller tires, go figure...
When I did the same change on my 98 my spedo was dead on after the tire change which meant it was spinning up milage faster with the smaller tires, go figure...
Starscream
NAXJA Forum User
- Location
- Columbia, SC
x2canadianwheeler said:
When I had to swap my cat I got a flat kind of low profile one put on and then went ahead and did a delta 40. I did gain back a marginal amount of mileage, but I think that was just because of the cat replacement.
90woodyxj
NAXJA Forum User
- Location
- Sebastopol, CA
i have a 90 cherokee. i get about 11mpg. got about 13 stock. id say 250 miles to the tank is really good!
sys_eng
NAXJA Forum User
- Location
- Saskatchewan Canada
Right now I'm averaging around 425-450 km / tank @ 105kph, & I'm driving around 4500km per month. about 18.5-19.5 mpg (imperial) 92 4L aw4 with ~5 inches of lift, heavy bumpers, winch, 31" MTs, it probably weighs in 400 or so lbs over stock.
I need to change my t-stat cause it's not warming up real good (only running around 190-195) that may bump my milage a bit.
I did notice an interesting drop in milage when I put on my winch, I removed a 1 1/2 inch lift shackle to compensate for the winch weight on the front, the rear was sitting about an inch higher than the front, my milage was running around 22-23 highway. Now the front sits about 1/2 inch higher than the rear (the winch didn't sag the front down much). I'm planning to pick up a 1 inch lift shackle to raise the rear backup a bit higher than the front.
Could the "brick" be slightly less brick like with the rear up a bit ???
I need to change my t-stat cause it's not warming up real good (only running around 190-195) that may bump my milage a bit.
I did notice an interesting drop in milage when I put on my winch, I removed a 1 1/2 inch lift shackle to compensate for the winch weight on the front, the rear was sitting about an inch higher than the front, my milage was running around 22-23 highway. Now the front sits about 1/2 inch higher than the rear (the winch didn't sag the front down much). I'm planning to pick up a 1 inch lift shackle to raise the rear backup a bit higher than the front.
Could the "brick" be slightly less brick like with the rear up a bit ???
Comanchedude
NAXJA Forum User
- Location
- Cincinnati,Ohio
I have a 89 Comanche 4.0 auto and 31" tires and get 16.5 to 17 mpg combo driving, and thats with 195k on the engine.
AJPulley
NAXJA Forum User
- Location
- South-eastern MA
250 miles to a tank sounds fine to me. I get maybe 280 if I stretch it.
langer1
NAXJA Forum User
- Location
- Mineral City,Ohio
Mileage is about 3-5 MPG better in comfort mode. Power mode drops mileage alot.