Horrible Gas Mileage

[LS4hundy]

I have driven 235 miles and im at a little less then a qtr tank!!

So just to make sure, the 95 ls400 has a 25 gallon tank? Ive had all the fluids changed/filters/plugs(not wires/distributor cap. I just moved to a small town(ashland) where I drive around 5 miles a day if that. Once a week, I hit the freeway. Dont drive with the ac on. I drive like a granny but there is a alot of stop and go here. I know that stop and go kills the miles but doing the calculation gives me like 10-12 miles a gallon. Suggestions? I will be driving back to seattle on turkey day which is 500 miles from here and im curious to see my mileage on a long trip.

Thanks in advance

1995 ls400 70k miles

[romy]

I have driven 235 miles and im at a little less then a qtr tank!!

So just to make sure, the 95 ls400 has a 25 gallon tank? Ive had all the fluids changed/filters/plugs(not wires/distributor cap. I just moved to a small town(ashland) where I drive around 5 miles a day if that. Once a week, I hit the freeway. Dont drive with the ac on. I drive like a granny but there is a alot of stop and go here. I know that stop and go kills the miles but doing the calculation gives me like 10-12 miles a gallon. Suggestions? I will be driving back to seattle on turkey day which is 500 miles from here and im curious to see my mileage on a long trip.

Thanks in advance

1995 ls400 70k miles

The best way to find out the mileage is fill the tank up, drive for 200 miles and fill it up again. Once you do that you will find that your car gives around 18-20 mpg, which is ok for a V8.

[nc211]

LS4Hundy, the mpg's in these cars flucuates like crazy. It's wierd sometimes. One day, you think the gas needle is stuck, the other you think there must be a hole in the gas tank. It depends on the environment factors, the tune of the engine and so forth. But, the most important thing that impacts the mpg, as you've witness, is the stop and go driving. It depends on the "go" part particularly. I'll give you an example: I recently moved to a different side of town. My office is 20 miles away. In my old house, it was stop and go all the way there "freeway traffic jams, all the time." My new house however, is the same distance, but my drive is now through the country side, with zero stop and go driving. I was filling up the car about once every 4/5 days on the freeway route, now, it's more like once every 8 to 9 days. I get nearly twice the mileage, and go twice as fast. The key thing is that I'm not dancing the gas & brake Jig. It's just go, no stop. I would sit out on that freeway, and probably crawl for 10 times in stop and go traffic. Stomp on the gas...Stomp on the brakes.

I would recommend a can of Seafoam in the gas tank when you head out to Seattle. Seafoam is a great fuel system cleaner, and best used when you're low on gas "pour it in before filling up to allow it to mix well", and then hit the highway for a bit, so the car gets good and hot. I think you'll like the results. Also, keep an eye on your air filter, that plays a big part in your mpg on these cars.

But, if you stomp on the gas a lot...you're going to burn through a lot of gas. Not like a Mustang 5.0 liter or anything like that though.

[blake918]

I have driven 235 miles and im at a little less then a qtr tank!!

So just to make sure, the 95 ls400 has a 25 gallon tank? Ive had all the fluids changed/filters/plugs(not wires/distributor cap. I just moved to a small town(ashland) where I drive around 5 miles a day if that. Once a week, I hit the freeway. Dont drive with the ac on. I drive like a granny but there is a alot of stop and go here. I know that stop and go kills the miles but doing the calculation gives me like 10-12 miles a gallon. Suggestions? I will be driving back to seattle on turkey day which is 500 miles from here and im curious to see my mileage on a long trip.

Thanks in advance

1995 ls400 70k miles

Your car has a 22.5 gallon tank. ;) I too live in a very small town. My morning drive across town usually takes me about 6 minutes, slightly longer if I catch the one red light. After I saw 13mpg one time, I quite computing the mpg, but typical city mileage for me is around 15mpg. Short city trips kill the mileage because it's easy for me to beat the EPA estimate of 25 on the hwy.

[falciott]

I would recommend a can of Seafoam in the gas tank when you head out to Seattle. Seafoam is a great fuel system cleaner, and best used when you're low on gas "pour it in before filling up to allow it to mix well", and then hit the highway for a bit, so the car gets good and hot. I think you'll like the results. Also, keep an eye on your air filter, that plays a big part in your mpg on these cars.

NC, let me ask you this.... once you put that Seafoam in ur gas tank, does it need to be consumed right away? If i were to just drive a bit and stop, will that bad boy evaporate? My gas mileage is not the greatest either, but it's probably cause of stop and go traffic as well, but I want to give that Seafoam a try though.

[nc211]

I don't think it will evaporate. I think you would be fine with around town driving, but I like it on a highway cruise becuase it prevents it from seperating from the gasoline itself. I don't if it would do that, but I don't if it wouldn't do that either...kind of like the oil and water effect. I doubt it would do that. I just like the highway part, because it's convient for me, and it goes all the way through, at a relatively higher rpm.

[93ls400walt]

The best result from Seafoam that I ever obtained. Was when I put it in with around 8 gal. of gas. Read the back of the can. It states that for maintaince use it with a full tank. For cleaning the fuel system, use it with 8-12 gals. I had a dramatic improvement in acceleration and peddle response. Haven't checked the MPG yet.

[LS4hundy]

well i feel alot better, I have been reading all these threads about guys so happy that they get great gas mileage on all the mileage threads. You guys are great, this forum is great, and my lexus is great. My fiance just started her career as a nurse and shes had the same corolla since 95, im trying to convince her to get an is(i think the older ones are smaller than the new ones). That would be nice to have both my boat and her sporty lex. Anyways, thanks again and i will update my mileage on my trip to seattle(cant wait to go back) Sea foam is nothing special is it? Can I get it at shmucks? Also, air pressure in our tire. Everybody seems to have a different opionon. I could care less for more comfort(there already plenty), i need better gas mileage!!

[Threadcutter]

Sea foam is nothing special is it? Can I get it at shmucks?

hundy:

Yep, schmucks have it, but they want about $7.50 a can, which is totally outrageous. Check Wally World & GI Joe's, they have it on sale periodically.

SeaFoam is made primarily of Naptha. There are other products out there that are similar. Berryman's B-12 Chemtool comes to mind as well. It is also made with Naptha as one of the primary ingredients. SeaFoam really isn't one of the seven wonders of the automotive chemical world. It is "just" Naptha with a few other additives. Same thing with Berryman's. I think they both work equally well. I find that Berryman's is usually quite a bit cheaper. I've paid as little as $2.50 a can at Wally World.

Either of these products are just a fuel system/fuel injector cleaner. Naptha is a solvent which breaks down & cleans all the gunk & power robbing deposits that are a result of tens of thousands of miles of normal use. Nothing tremendously magical (in spite of what the marketing geeks say). You can also accomplish the same thing by taking your car into a good "Indie" and having the fuel system/injectors cleaned. But guess what they use? Well, maybe not SeaFoam, but something very similar. It will usually run you about $150.00, which isn't terrible. You can do the same thing over time by adding a can to your gas periodically. I usually add an entire can to a quarter tank of gas, which will probably elicit howls of protest here, but if you figure out the dilution ratio for four or five gallons of gas to 16 oz's of "goo", it's not that bad.

Stay away from the "Techron", Valvoline, STP type of treatments.......It's the same stuff in a fancy bottle for about four or five times the price of SeaFoam.

As a side note; I don't quite understand all of the discussion about wildly fluctuating mileage numbers. If I use cheap gas or do a lot of in city driving, I get 23 to 24 mpg. If I use good gas or drive mostly highway, I get 25 to 26.5 mpg and it's always been that way. However, keep in mind that I started with SeaFoam the day I bought the car. The most notable improvement was pedal response. I could definitely feel the improvement there. But it's not like I went from 17.1 (or something) to 25 mpg.

[mls]

Just drove 1000 miles, all interstate with cruise set on 70. Got 28 mpg with premium gas. I was only person in the car and had no luggage or extra weight. I was really surprised. 95 LS 400

[LS4hundy]

Sea foam is nothing special is it? Can I get it at shmucks?

hundy:

Yep, schmucks have it, but they want about $7.50 a can, which is totally outrageous. Check Wally World & GI Joe's, they have it on sale periodically.

SeaFoam is made primarily of Naptha. There are other products out there that are similar. Berryman's B-12 Chemtool comes to mind as well. It is also made with Naptha as one of the primary ingredients. SeaFoam really isn't one of the seven wonders of the automotive chemical world. It is "just" Naptha with a few other additives. Same thing with Berryman's. I think they both work equally well. I find that Berryman's is usually quite a bit cheaper. I've paid as little as $2.50 a can at Wally World.

Either of these products are just a fuel system/fuel injector cleaner. Naptha is a solvent which breaks down & cleans all the gunk & power robbing deposits that are a result of tens of thousands of miles of normal use. Nothing tremendously magical (in spite of what the marketing geeks say). You can also accomplish the same thing by taking your car into a good "Indie" and having the fuel system/injectors cleaned. But guess what they use? Well, maybe not SeaFoam, but something very similar. It will usually run you about $150.00, which isn't terrible. You can do the same thing over time by adding a can to your gas periodically. I usually add an entire can to a quarter tank of gas, which will probably elicit howls of protest here, but if you figure out the dilution ratio for four or five gallons of gas to 16 oz's of "goo", it's not that bad.

Stay away from the "Techron", Valvoline, STP type of treatments.......It's the same stuff in a fancy bottle for about four or five times the price of SeaFoam.

As a side note; I don't quite understand all of the discussion about wildly fluctuating mileage numbers. If I use cheap gas or do a lot of in city driving, I get 23 to 24 mpg. If I use good gas or drive mostly highway, I get 25 to 26.5 mpg and it's always been that way. However, keep in mind that I started with SeaFoam the day I bought the car. The most notable improvement was pedal response. I could definitely feel the improvement there. But it's not like I went from 17.1 (or something) to 25 mpg.

Wow, you are getting almost double the miles per gallon than me!!

[Threadcutter]

mls:

Got 28 mpg with premium gas. I was really surprised.

Don't be......

hundy:

Wow, you are getting almost double the miles per gallon than me!!

Yeah, I think you've got something going on that should be looked at. Maybe have an Indie give your Fuel Injectors a bath. Or at least have it looked at for some recommendations.

[blake918]

Wow, you are getting almost double the miles per gallon than me!!

You're comparing apples to oranges though. No car (even a VW diesel or Honda Insight) is going to return reasonable gas mileage running such short trips. If I visit a larger city, my city mileage shoots up to 18-20 like it's supposed to be. If I didn't get 25-26.5mpg on the hwy, I'd suspect something is wrong with my car. Do some interstate driving, and that will give you an idea as to if there is something wrong with your car's mechanicals...because "city" varies from person to person.

[LS4hundy]

So I am leaving for seattle tomorrow which is 500 miles from here(ashland oregon). I bought a bottle of berrymans(comparable to sea foam) and I have 40 psi in the tires for the gas mileage. Does anybody else have any mileage booster advice. I will let everybody know the mileage i get on the highway when i get back. Im thinking of setting the cc to 70-75 mph. Hoping to get 25-27 miles per gallon.

HAPPY TURKEY DAY TO ALL

[93ls400walt]

The best result I obtained was when I used it with aroud 1/4 tank of gas.

[93LSOwner]

Does anybody else have any mileage booster advice.

http://fueleconomy.gov/!Removed!/driveHabits.shtml

[LS4hundy]

The best result I obtained was when I used it with aroud 1/4 tank of gas.

Just so i make sure, u had 1/4 tank then filled up, if so, i have about 1/4 tank right now but plan of filling up with gas tomorrow before i leave

[93ls400walt]

I ran the car with 1/4 tank and the seafoam before filling up. I drove about 100 miles like this then filled up. I noticed a hugh difference in engine response within the first 30 minutes. I have not checked my MPG since. But I am totally thrilled with the increased performance. And I am assuming that the MPG will be better since the engine is running more efficent. The idea is to run it at a more concentrated state. The instructions on the can states something close to: use with a full tank for maintance. Use with around 8 gals. for cleaning.

[rtd111]

Isn't there some side effects to using Seaform/Berryman's or a follow up action?

Like the gunk / carbon that it loosens, where does it go? Does it get trapped in a filter / exhaust-system that needs cleaning. I recall reading a lengthy article on this forum about pro-cons once (but could not locate it when I just searched for it -- I get an error, likely operator error.)

[CanadaCraig]

Hi 93ls400walt!! :)

I've been reading your messages in this thread with great interest. My 93 LS is now averaging 15.82 MPG. That's down almost 1 MPG from the last time I checked. [A few weeks ago] My car also [very often] accelerates poorly. [Taking 12 or so seconds to reach 60 MPH] I'd like to try something like Seafoam. But I share rtd111's concern. What happens to any of the gunk and carbon that something like Seafoam might loosen up? Is any part of the car put at risk because of that loosened 'gunk'? [O2 Sensors - or whatever] Also... would Seafoam help my car perform better considering the fact that my injectors have already been cleaned - several times - by the Lexus mechanics I go to? Does something like Seafoam clean more than just the injectors? A lot of questions - I know - but if you [or someone else] could answer at least some of them - I would appreciate it.

Thanks,

Craig!! :)

[93ls400walt]

HI Canada,

I do not know for sure if the particals removed via seafoam will do any harm to those componets. What I do know is that In the year that I have owned my Ls. I have used seafoam at least six times. As well as a can od BG44K from the Toyota dealer. Most of those times it was with a full tank of gas. I onlynoticed a slightly smoother idle. Then about one month ago I used seafoam with 1/4 tanke of gas. After 1/2 hour if driving I had a significant improvement in my acceleration. No time trials or anything like that. But I no longer had the feeling that upon acceleration that I was " pulling " a mobile home behind me. And it has remained since then with improved acceleration.

I am sure that it is possible but unlikely that any deposits removed could affect your plugs, cats &O2's. The thread that I read on seafoam fouling plugs, ect. was when you used it via the brake vaccum hose. Sucking 1/4 cup into the air intake chamber.

If the dealer has cleaned your injectors. I am not sure of any added benifit of running it through the entire fuel system. But my feeling is that it could not hurt. And it my help if there are any flow restricting deposits prior to the injecters.

Has your timming been looked at? As far as advancing under acceleration? Also is your trasmission shifting up gears at the correct speed and throttle position? I don't know those answers. It would have to be looked at by someone who knows the specs.

The is a performance shop in my town that has a Dynomometer ( spelling ). It is where you put the car onto a rack with the rear wheels on rollers. And the engine electronics are connected to a computer. You then run car under different acceleration speeds. Your horse power ect can been determined. And is used for fine tunning race cars/street rods. I am planning to see if the will inspect my ls. Their cost is &150.00us. for a tune on the machine.

Good luck, Walt

[swordfish]

hi craig and the rest of you guys,

I have the acceleration problem after 4000rpm, and get about 15mpg (imperial , which is less in US gal)

around town. Pure highway set on cruise gives about 27mpg, but i hardly do hwy, just mostly around town for work.

My mechanic always thought it felt like timing was out, or not advancing. Ihave had static timing checked several times, and alll marks align as they should, with no. 1 piston on top dead centre. Since fitting the new genuine spark plug wires engine is much smoother, and a hot idle miss in gear has been cured, but power problem persists. It does drive superbly, until you try to accelerate hard. Overtaking on highway back roads where full throtte power is needed at speed is just dangerous and almost impossible, you have to back off and let it change up a gear and keep rpms below 4000 to accelerate.

Have changed;;; belts, idlers, w/pump, fuel filter air filter, cats, exhaust from engine pipe back,wires, plugs, leads, rotors, caps, cleaned throttle body and injector and fuel sys cleaned.

Lexus have done scans and found nothing, as have 2 other good mechanics.

They say o2 sensors are fine, and tps, while worn, is still ok, temp sensor seems to work fine, starts on high idle cold, and ramps down as it should.

any more ideas appreciated. :(

[93ls400walt]

There is a KICK DOWN SWITCH for the transmisson. Not much info in the manual. It is located on the floor board under the gas pedel. It ( I think ) is suppose to "kick down" the transmisson. When you press on the gas pedel to increase your speed when the throttle valve is already fully open.

The book does not list any tests for this. I hope someone has some more info on this.

[LS4hundy]

wow, im glad to still see this thread going strong. So I just got back from my trip and here are the results. Its a 463 mile trip. On the way to seattle, I left with a full tanl. I poured a whole bottle of berrymans in while i filled up the gas tank. I didnt top of the gas, just till the first click on the gas pump with chevron premiun. On the way there i stopped a couple times and stayed in portland putting about 10-15 more miles on to the trip. I made to seattle on 1 tank. The next day the gas light came on. So for sure i got about 480 plus how ever much gas is left in the tank when the gas light comes on.

on the way back, had less weight in the car, filled up with shell premium, no stops other than rest stops(twice) and just made it while the gas light came on about 5 miles before i got home.

Both trips I used cc at about 75-80mph.

what do u guys think. I find it interesting that i had less weight and didint do any extra driving and i got less mileage.

I figured that if i add the 10-15 miles for driving in portland to the total of the 463 mile trip that brings the total to 480 miles plus u have to figure i had atleast 10 more miles when the gas light came on, thats 490 miles total. Doing the math thats 22 miles/gallon and also i didnt top of the gas(dont know if that matters much)

I want to say thanks to everybody who gave advice and it was exciting to see my results and I would not have been that excited if it wasnt for this site....

She drove like a dream!!!

[93ls400walt]

Hello again Canada,

I received the British car mech. mag. The one with the ls 400 diag. info. Just 2 1/2 pages. I did not find much usefull info. in it. Though it did however discuss the general lack of power prob. Though there is usually a fault code for the cam/crankshaft position sensors. The problem often is with the Alt/power steering belt having worn the insulation off the wires and letting them short out. This causes the ecu to set a lower Rev limit. And causes the phasing of the fuel injectors the be non-sequential. Also stated is the poss. of the timming belt having "jumped" a notch. Or missfitted during a new instalation.

Just another area to look at.

Walt