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Tips On How To Increase Mpg?


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I have a 1993 LS400, 146,000.

I only get 10.5 MPG in the city, in rural area. Every day I go to school and stop at about 3 stop lights then the speed limit is 55mph after the third stop light. Total miles to school is 10 miles so a around trip daily is 20miles. After the third signal there are 8 miles to go, “when going.” What I am trying to get at is that I don’t stop very frequently and drive at a high speed but still very poor miles per gallon. I only use Premium gas. And take off very slow, no flooring.

1. What kind of Lexus you have?

2. Year?

3. Miles?

4. MPG?

Got any tips or suggestions on how to increase MPG? Every gallon helps!

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92 LS400, 85k miles, 22-30 mpg imperial, city-highway. Under your driving conditions my car would give about 20 mpg US. Either your car has a problem, or the method you use to collect and compute the data is wrong.

Best method is to fill the tank to the first click off, record mileage only, not fuel. Drive until the tank is at least 2/3 empty, fill and repeat two more times. Record the fuel used to top the tank off on these three times. Record the mileage, and subtract the first mileage from it, divide those miles by the total fuel used to cover them.

These cars get amazing fuel economy regardless of how old they are, as long as they are in good tune. The fuel/air ratio at 100k is essentially the same as that at 10 miles, as the computer's programmed values do not change. An O2 sensor going out of range would increase fuel consumption, but that would also trigger a trouble code.

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94 LS400 116K about 12MPG 90% city, ECT 'power' on all the time, octain 93 always. my 96 SC400 167K is about the same.

I drove less than 20-miles a day, but that can mean 10+ stops (engine on-off) because I work from home office. most trips are to vendors and UPS within 5 miles radius.

funny thing is if I turn ECT off, the MPG goes down to 11~10.5 which is on the contrary to some suggestions in this forum.

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99 LS - 60K

I have trip similiar to yours except ony 7 miles one way with 3 lights, 5.5 mile highway stretch.

I average 22-23 mpg in this "cross trained" city/highway blend. 28+ on full hwy.

Have you checked your Air Filter & plugs lately... a fresh set could do wonders?

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94 LS w/ 185k. Driving distance to and fro 60. Beltway stop and go, with a brisk 55mph once on the beltway. Average 1.4 gallons to and fro.

I have to agree with some of the other guys. It sounds like you may have a bad 02 sensor, dirty air filter, or something else is wrong with your car to get such a poor economy. My dad(owned my car before me) would probably get 1.0 or less if he drove it, for the same distance.

Suggestions:

-Replace Air filter with K&N filter-Injen or basic round filter will do the job as well.

-Switch to Mobil 1 5w30 or 10w30 (Synthetic) depending on the condition of your engine--I've run tests for Mobil on several occasions. One of the best oils.

-Run Error code test. Free testing at an AutoZone, or at a trusted Tuner shop or mechanic's shop. If you have a code 25, you're going to need one or more new O2 sensor(s).

-Check Tire pressure, All; keep at 30psi, unless you have a full car(load).

--Optional: getting an ARC recorder that plugs into your OBD1 ECU.

Driving Tips:

-Start car first thing, and let idle for 20-30 secs, before putting into D or R.

-Drive slowly; keep below 2000-2500RPMs until Oil is Completely warm--line at half mark.

-Increase speeds, but keep your distance from the car infront of you--About Two to three medium car lengths.

--Look at least a mile down, and learn to predict the pattern of driving and traffic infront of you.

--If traffic is slowing down, take your foot off the throttle, and gently depress brakes--DO NOT LATE BRAKE, and let the car glide itself(momentum). You can take the car into Neutral if you wish, but do not apply the brake completely, until it's absolutely needed. Most fuel is lost during late braking and standing at a traffic light with the gear in drive. Brakes also get warped quicker if you late brake, and give the rotors less time to cool down.

--Let the car drive itself, instead of you alway depressing the throttle most of the time.

These tips should help you get better fuel mileage. Remember they call our cars, boats and grandpa machines for a reason. You kind of need to drive like a grandpa in order to get good mileage. :)

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Suggestions:

-Replace Air filter with K&N filter-Injen or basic round filter will do the job as well.

-Switch to Mobil 1 5w30 or 10w30 (Synthetic) depending on the condition of your engine--I've run tests for Mobil on several occasions. One of the best oils.

-Run Error code test. Free testing at an AutoZone, or at a trusted Tuner shop or mechanic's shop. If you have a code 25, you're going to need one or more new O2 sensor(s).

-Check Tire pressure, All; keep at 30psi, unless you have a full car(load).

--Optional: getting an ARC recorder that plugs into your OBD1 ECU.

These tips should help you get better fuel mileage. Remember they call our cars, boats and grandpa machines for a reason. You kind of need to drive like a grandpa in order to get good mileage. :)

I follow the exact driving tips you gave us. Execpt that in the mornings I warm the car up for about 10min not 10-30sec. I'm going to print this list out and show it to my machanic. But what is a 02 Sensor, he is just a local machanic but knows about Acuras and Toyotas, will he know what 02 Sensor is? And what is the exact job of--"Optional: getting an ARC recorder that plugs into your OBD1 ECU."

Thank you very much. I think spending money on these repairs, if they work, will save me more money overtime; rather then filling up the tank every 5 days.

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i have 1994 ls400 with 111K. i get baout 19 city 22 highway. i have an injen intake and bored out intake manifold (seems to help a little). seems that somehting is wrong with your car, s take it to the dealerhsip to get i diagnosed. i used to have a 1993 with nothing modded on it and i florred it everywhere and my mpg was horrible. in my new ride i barely waste much gas driving to school. the intake helped. so you should maybe look into one

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My strut bar makes a "clunking" noise when I hit a bump. People here at LOC told me that it was the strut bar making the noise as well as my machanic but I don't know how the bushings are? I think it is called adjmust/shimming for vavles, think I need that, because engine makes a noise like tick,tick, tick. The last owner told me his machanic said that it is not harming the engine in any way. Are these things playing a role in the MPG issue.

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These engines do make a clicking sound, but that can be valves or injectors. A mechanics stethoscope will isolate which is which.

The valves, if they are out of adjustment, are not causing the poor fuel mileage. As 98LS pointed out, the fact that you idle the engine for 10 minutes every morning is doing that.

When a car engine is running, and not moving, it is getting ZERO miles per gallon. Doesn't matter if it is a Honda or a Kenworth. ZERO. So with you idling for about as long as it takes you to drive, your mileage will be terrible.

Start the engine, wait ten seconds, drive. Do that for several tank-fulls and then tell us if your fuel mileage is still bad. There is no need to warm up the engine in that manner.

Stop worrying about it until you change that habit and test again.

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92 LS400, 85k miles, 22-30 mpg imperial, city-highway. Under your driving conditions my car would give about 20 mpg US. Either your car has a problem, or the method you use to collect and compute the data is wrong.

Best method is to fill the tank to the first click off, record mileage only, not fuel. Drive until the tank is at least 2/3 empty, fill and repeat two more times. Record the fuel used to top the tank off on these three times. Record the mileage, and subtract the first mileage from it, divide those miles by the total fuel used to cover them.

These cars get amazing fuel economy regardless of how old they are, as long as they are in good tune. The fuel/air ratio at 100k is essentially the same as that at 10 miles, as the computer's programmed values do not change. An O2 sensor going out of range would increase fuel consumption, but that would also trigger a trouble code.

This is how I tested.

When I bought the car it had 146084 miles. Thats when I pulled it out of the last owners drive way with FULL tank. At 146200 the full was in exact middle. So, I figure that the fuel tank holds 22.5 Gallons that would be 11.25 (22.5/2) Gallons used.

So, 146200-146084= 116miles.

116miles/11.25gallons= 10.31MPG.

Is this an accurate calculation?

Nobody drives this car except for me and I only take it to school. Which is 10miles. 20miles around trip, each day. And I can physically tell that it drinks that much gas by looking at how much the needle drops after 3 days.

But I do idle for 10min. I'll try to drop it to 1min. The temperature is around 20C here. But when I pull out of the school parking lot to come home in the afternoon I start the car and pull out in about 30sec., but still get the same results, in the morning and afternoon. I can physically compare the morning and afternoon gas consumption because the needle drops so much without doing any calculations.

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All the gas gauge tells you is when to fill up the tank. Unless the previous owner lived at a gas station, some fuel was burned going home. You must fill the tank, record the mileage, drive the car and fill the tank again. What was needed to fill the tank the second time is divided into the miles driven. The gauge is not linear in its reading. And you should do this several times.

Why do you insist on warming up the engine? Has someone told you it was a good thing to do? It isn't. Start the engine. By the time all the annunciator lights go out on the instrument cluster, put the thing in drive and go.

Your actual fuel mileage is far higher than you think.

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As 98LS pointed out, the fact that you idle the engine for 10 minutes every morning is doing that.

When a car engine is running, and not moving, it is getting ZERO miles per gallon. Doesn't matter if it is a Honda or a Kenworth. ZERO. So with you idling for about as long as it takes you to drive, your mileage will be terrible.

Start the engine, wait ten seconds, drive. Do that for several tank-fulls and then tell us if your fuel mileage is still bad. There is no need to warm up the engine in that manner.

Stop worrying about it until you change that habit and test again.

93ls,

Heed these words of advice - They are excellent!

You can't tell your mileage by looking at the guage. Do the math for accuracy.

Technically, you get the best mileage on the last half of the tank of gas. So run it down to a 1/8 tank before you fill it up.

Just get moving within 30 seconds... you can go slow and ease into it.

Look at it this way; in 8 miles of your hwy stretch, this will take you 8 minutes - but you've still got your car in the garage!

You may have problems, but let's see if you can get 14 mpg first.

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Suggestions:

-Replace Air filter with K&N filter-Injen or basic round filter will do the job as well.

-Switch to Mobil 1 5w30 or 10w30 (Synthetic) depending on the condition of your engine--I've run tests for Mobil on several occasions. One of the best oils.

-Run Error code test.  Free testing at an AutoZone, or at a trusted Tuner shop or mechanic's shop.  If you have a code 25, you're going to need one or more new O2 sensor(s).

-Check Tire pressure, All;  keep at 30psi, unless you have a full car(load).

--Optional: getting an ARC recorder that plugs into your OBD1 ECU.

These tips should help you get better fuel mileage.  Remember they call our cars, boats and grandpa machines for a reason.  You kind of need to drive like a grandpa in order to get good mileage. :)

I follow the exact driving tips you gave us. Execpt that in the mornings I warm the car up for about 10min not 10-30sec. I'm going to print this list out and show it to my machanic. But what is a 02 Sensor, he is just a local machanic but knows about Acuras and Toyotas, will he know what 02 Sensor is? And what is the exact job of--"Optional: getting an ARC recorder that plugs into your OBD1 ECU."

Thank you very much. I think spending money on these repairs, if they work, will save me more money overtime; rather then filling up the tank every 5 days.

Sorry didn't mean to respond so late.

02 is Oxygen sensors. If your local mechanic has a good code reading machine, he/she won't have any problem reading the code, if you have the code. I would suggest going to your mechanic for this only, and maybe the oil change.

Sorry, ARC is a wireless management system onboard many race cars. The one you can plug into your car is the SAFC- made by Apexi, greddy, and is a plug and play monitoring system. Shoot an email to Steve@lextasy.com or Private Messager MrSypher--Moderator on the GS Forum. They can help you get it, if you want. ECU or ECM is the master computer for the car. Most ECUs have open ports you can use, to add devices.

10 minutes worth of warm up is okay, but under 1 minute worth of idle warm up will be best. Many mechanics and I have concluded even-warming for the car(engine, tires, transmission, fuel tank, suspension, etc) is better than just engine warm-up. Your car will wear evenly.

I will be honest, the LS400 is a fuel guzzler. Most of us don't complain about fuel problems like not getting good mileage or fuel prices @ the pump, because we can afford the car. Since you're still in school and may not have a stable job, it's not wise to have such a big car. You're going to end up wasting money in the long run. A Toyota or the Lexus ES250/ES300 would be my choice.

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91 ls400, 177000 miles, 26.5 mpg. I normally drive with my foot on the floorboard. Drive with your right foot doing the gas and the left foot working the brake, drive as smoothly as possible. whenever you get behind the wheel, assume everybody is a idiot, alway drive in the front of a pack of cars or in the back of them, never drive in the center with them, you have no time to react to a accident.

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UCF3,

I am 17 years old, High School Senior. Only worked for one month all my life. Right now looking for a job. Anyways, the last owner warned me that it takes alot of gas. But I was just wondering that is it just my car. Since from my point of view it was a little bargin. $5,800 1993 LS400 146,000 that it might have problems. The reason why she sold it was because she bought a newer Lexus LX470. Today, I only idled for 1min in the morning and 20sec in the afternoon. I just heard that not warming your engine may cause it to seize. I guess it is just an old myth, "not from a machanic." I live in High Point, NC I was searched for a Lexus for 1.5 years. There was one in the paper for $6,500 1994LS400 134,000miles and it got sold the right next day after it came in the paper. So, I had to get this one. I never thought that I would buy a LS400 since it is a V8, the PRICE and how rare they are to find under $10,000 with descent miles.

There are few people who have new expensive cars like a 2000 BMW 3-series and 2000 Discovery. But I'm the only one with a $46,000 car and a LEXUS. It is well worth the price, price of parts, gas and everything else.

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No, but thanks though.

I was just wondering if there are other things. Like replacing some major components that cause the MPG to decrease. Or like on some Commercials on TV, I think its called Max something, it is purple in small bottles, that you put in your car and gives you better mileage.

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