Questions - Gas Mileage - '99 LC

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uzj100

uzj100

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Oriental, NC
The History - I have a '99 LC with 88k miles. It gets terrible gas mileage, 11 mpg. However, about a week ago, I got a CEL so I checked all hoses and connections. I found one vacuum tube disconnected under the plastic engine cover. I reconnected that hose. SO then I disconnected the battery to see if the CEL would go out and stay out. It did not, it came back on after about 50 miles. I then went and had the code read and they said it was the bank 2 sensor 1, heated 02 sensor. Also, I have not changed my driving style one bit or have used any different gas octane, I always use 92 octane.

Thats the history, now for the questions.

My gas mileage has dramatically increased to like 12.6 mpg.

1. Is this because I disconnected the battery and the vehicle has not learned to return bad gas mileage yet?

2. The O2 sensor is not functioning and effecting the gas mileage. This is a stretch. I am thinking no way.

Now for the weird part, can a OBD2 reading give incorrect information. When I was under the LC looking for loose connections, I came across a strange thing. A little grey connector was disconnected, down by the axle on the bank 1 side of the vehicle. I could not figure out where it connected too so I left it. After referring to my Repair Manual V2, it appears to be the other end of a o2 sensor but it is on the wrong side of the engine. I will check it closer tonight now that I have a clue as to where it is suppose to be connected. I wonder if the Toyota dealership disconnected this when they replaced the cv boots on both sides and that is causing the CEL.

I will let you know what I find.

uzj100
 
Just as a refernce, I have a 98LC with 67k miles and do mostly suburban driving, have the same tires as you (BFG AT's) and I get 13.8-14.0 mpg after correcting for tire size (odometer reading/miles multiplied by 1.054)
A disconected O2 sensor can be affecting your mileage. The lift and the extra weight of the ARB and the winch can also reduce mpg. However, I do hope that the lift/ARB do not have that much an effect, since that's on my mod list in the near future.
If anyone has some figures on that, please post.
mtycruiser
 
13.8 to 14 mpg. Holy cow. That is insane. I reset the trip odometer everytime I fill up. I usually get to about 230 miles recorded before the fuel light comes on. I then fill up and usually take on 21 gallons. If I adjust the 230 miles to 242 (for the tires) then divide by 21, that equals 11.54 mpg. That sucks. You are averaging at least 2 mpg more than me. This tank full is different, I am at 260 miles and the light just came on. adjusted for 1.054 equals 274 miles. I will fill up in the morning and let you know how many gallons I take on. The bumper weights about 75 lbs and the winch weights 125 lbs and the odessy battery weights like 55 lbs (about 15 lbs over stock).

Thank you for the info.

uzj100
 
I've been watching mileage on my 99 since I bought it in April. In city driving, I get anywhere from mid 13.5 to 14.5 mpg. In purely highway driving, I can get up to 16+ mpg. That is about what I expected, and I get the feeling from reading the prior discussions on mpg that I'm doing okay. Good luck.
 
Ok, what in the heck fire I am doing wrong? I have been going easy on the take offs and trying to keep it under 80 mph on the freeway. Could it be the extra weight? the lift, the tires, the speed? How fast do you drive on the highway? If I got 16+ mpg on the highway I would throw my cruiser a party.

Thanks,

uzj100
 
I recently drove my 99 on a 4000 mile trip. At 80-90 I got 14-15 mpg. If I took it easy I could get 17 pretty easy. I havent done the math around town but it seems like its still pretty good.

BC
 
Lets run a survey or something. When do you fill up? When the light comes on? When the light has been on for a week? or when the trip odometer reads 250, 300 or 350 miles? On average of course.

uzj100
 
Omg - Yamt

Oh My God - Yet Another MPG Thread -- At least this one's 100-specific and won't get Junk's usual complaints.

My 99 gets over 17 on the highway -- very close to 18 if I'll hold it to the speed limit or less.
A tank of combined driving around the mountain and into A-ville and back once or twice is about 14 mpg and a shade.
A whole tank just on the mountain is 12 mpg or a bit less. That's a lot of very slow, steep driving.

I fill up on Monday's because that's when Ingle's puts high test gas on sale at 7 cents off. If I haven't been into A-ville but once, I only burn a half a tank a week.


HTH
:cool:

LT
 
That does help. And even an east coast response. I live in Raleigh and my parents live in Campello (spelling). The area where you live is awesome.

Thank you for the response. I think I need to slow down to save the most gas.

uzj100
 
I got 15+ mpg in normal driving with premium gas and about 12 MPG with regular gas. That is uncorected with 285/75R16. With gas price as high as now it makes more sense for me run premium since the price differences are about 10% and I got 25% better mileage.

Your result may vary. This is just my personal observation from running regular gas the first few months the gas price went up.

Unconnected oxygen sensor would result the engine to run in closed loop and yes it would burn more gas.
 
ELLTEE said:
Oh My God - Yet Another MPG Thread -- At least this one's 100-specific and won't get Junk's usual complaints.

My 99 gets over 17 on the highway -- very close to 18 if I'll hold it to the speed limit or less.
A tank of combined driving around the mountain and into A-ville and back once or twice is about 14 mpg and a shade.
A whole tank just on the mountain is 12 mpg or a bit less. That's a lot of very slow, steep driving.

I fill up on Monday's because that's when Ingle's puts high test gas on sale at 7 cents off. If I haven't been into A-ville but once, I only burn a half a tank a week.


HTH
:cool:

LT
Click to expand...

Yeah, keep in mind that wind resistance rises with the square of the velocity, so twice the velocity means 4x the wind resistance. I got my '86 4runner 4-banger (OME lift, ARB/kaymar, synthetic everything, etc.) tweaked so it gets 25.3 mpg corrected in city driving (35-50mph), but it plummets to 23.5 mpg at 72mph on the freeway and more like 21mpg at 75mph. The 100 is at least more aerodynamic. A friend of mine has a '01 100, gets 15mpg average around town (all stock, including tires).

--Jim
 
So ... when you fill up, do you fill it all the way to the brim or do you stop putting gas in it after it clicks off.

I ask because how do a person know how much gas was burned off. We know that when the gas light goes on, there is 5 gallons left and we assume that we just burned off 20 gallons. So 243 miles divided by 20 gal equals xxx. Is any one getting this? I can try to explain better.

I went to South Dakota 2 months ago, and I was getting between 17mpg - 19mpg. I used cruise control a lot but at 80mph. I did put the stock tires on the truck, custom front and rear bumper, extra 160 ltr tank and "stuff" in the truck for the 2 week trip. I do have a TRD supercharger. I know the s/c helps because I don't have to put the gas pedal down as far to change speed or just moving.

Thanks, I am trying to get a baseline with the gas filling up part and consumption. I am not regretting the s/c as amatter of fact I recommend it, since none of our trucks are getting lighter, it gets heavier each time we buy something for it.
 
I run my truck until the gas light comes on. At that point I reset trip odometer A back to zero, then usually run about 25 to 30 more miles. I fill the truck up until it clicks and then let the gas run one more time until clicks (very short) - just to make sure it is full. I then get a receipt to determine exactly how many gallons have gone in.

Today's fill up - 22.861 gallons
Trip Odometer B Reading - 284.5 miles (adjusted for 285's - times 1.054 equals 299.86)
MPG - 12.44 mpg (13.11 mpg adjusted for tires)

This is the best I have ever done in suburban driving (some city, some highway).

I am going to continue to slow down and see how good I can do. My whole thing is that I do not want to run out of gas so I always have about 3 to 4 gallons of gas in my truck at fill up. I wish I could get to about 1.5 gallons left. The tank holds 25.4 gallons. 300 miles at 12.44 mpg (not adjusted for tires) would equal 24.11 gallons of gas which would leave 1.29 gallons to play with.
 
I am going to continue to slow down and see how good I can do. My whole thing is that I do not want to run out of gas so I always have about 3 to 4 gallons of gas in my truck at fill up. I wish I could get to about 1.5 gallons left. The tank holds 25.4 gallons. 300 miles at 12.44 mpg (not adjusted for tires) would equal 24.11 gallons of gas which would leave 1.29 gallons to play with.[/QUOTE]

uzj100:
Don't play with your luck, if you want to check mileage on a bigger sample of miles, put a fixed number of gallons (10? 15?) on your tank and keep driving without resetting the odometer, next time, fill the tank and add the number of gallons you put in between fill-ups and do the math.
Another difference in mileage can be from the transmission (4 sp vs 5 sp), mine is the 4 sp and I suspect a 5 sp can give you better MPG.
Other factors as speed, temperature, how fast you accelerate, altitude, cargo, etc have a big impact on MPG, so far my best has been 16MPG (highway, flat, 65-70mph, cold temp, no a/c) and my worst 12MPG ( hilly, fast,a/c,loaded) overall, as I have said before my avg. is very close to 14MPG with the 4 spd. transmission.
 
I never let my truck get under half a tank. The fuel pump is in the tank and it is cooled by the fuel. The more fuel the cooler it runs and the longer it lasts. Just a thought. I get 17 mpg city and 19 mpg highway. Normal combined is 18 mpg. But my truck weighs 500 lbs less. Lose weight it will make a difference. Also run OEM size tires it will also make a difference. Rolling resistance is a big deal when it comes to mpg.
 
Pitbull said:
Yes :)
Click to expand...
How did you reduce the weight of the stock vehicle by 500 lbs? Removing the front d-shaft, diff, and axles? :-)
 
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