yotoy82

IMO, 17 mpg in combined city/highway driving is pretty good for a 97 LS in summer driving. I drive with a light foot and get barely 18 mpg in combined city/highway driving in summer. The 98-00 LS400 like mine with the 5-speed tramsmission generally gets a bit better mileage than the 4-speed 95-97 LS. I'd be more interested in what your gas mileage is over five to ten tank fulls. Don't fill your tank until the fuel gauge is below 1/4 and then manually calculate. Try to fill you gas tank the same way each time ... i.e. fill slowly and stop with the pump automatically turns off to be consistent. I've tracked every gallon of fuel that has gone into my cars for 46 years and have found a high degree of variability with mileage being better in Spring and Fall and worse in Winter and Summer.

Jim...better check your alignment. :P

To the OP. I was wondering if your LS is reporting the correct mileage since you are using the Iphone app. Is a mile really a mile? You don't have "20's" on this thing, do you?

Stock 16 inch chrome wheels. I manually calculate as well, the app just helps me keep a record. I get from 9-12 mpg in city and from 17-23 mpg highway on a good day. I'm pretty sure thats how much big SUV's get lol.

"Just had a wheel alignment done at my toyota dealership. They said the rear was fine and the front was slightly off."

Did you get the 'Before and After' printout?! Did they check the suspension components?! I can guarantee that if you have never replaced the ball joints, strut bars(front camber adjusting bars), and rear trailing arm bushings, they are most certainly worn out by now! No tech likes having to make all the adjustments/repairs necessary to correct the alignment on an old LS400 since they don't get paid any extra for adjusting front and rear camber(bolts are usually stuck by now), but when it is done properly the results are amazing. For most of these guys(dealerships included), it's "Set the toe and let it go!". An i-phone app for fuel economy? Seriously? Nothing works better than pen and paper.

I had the strut bars replaced, lower ball joints replaced, on the front end, both sides right before the alignment. Had the other components checked out, surprisingly everything else was in pretty good condition.

I'm NOT sure about rear trailing arm bushings, what are those? The car has 207,000 miles on it and I would say that 90% of that is highway so a lot of components on it have held together pretty good, but not sure about rear trailing arm bushings.

And the iphone app, it just helps keep a record for me rather than pen and paper and calculator lol.

And I took the car to 50 mph today, put it in neutral and let it coast, seemed to stay up at a high speed for quite a long time.

Video enclosed here of it.

I thought about this too. I regularly take my foot off the pedal and my LS400 drives forever on its own, almost made me worry about the transmission. I can literally coast forever even if I take my foot off the pedal on a flat road going 40 miles per hour, it just keeps on going and going and going! lol. But will check it as you say just to be sure.

You will coast some with the car in drive as the engine will transfer some torque to the wheels even with engine idling. That could extend your glide distance. You could pop it into neutral and see how far you glide.

I like the heat idea better though because if brakes are dragging they're going to get hot. Its simple physics. Energy dissipated as heat.

If it was dragging though wouldn't the RPM's be higher for a given speed? But ya going to take some advice here and give it a check. Is there any other way to diagnose if the brakes are dragging besides looking for heat? I mean its summer anyway so I don't know how much heat extra I'll be able to tell a difference. Can I have the wheels taken off and check anything in particular?

There is something very wrong with the car based on your MPG. I routinely get around 19MPG in stop and go short trip city driving and high twenties on highway trips.

I have been having problems with emissions and one catalytic converter so it has me looking at similar things. An invaluable tool has been an OBDII interface and my laptop computer. I can set up gauges to look at fuel trim, short term (ST) and long term (LT). Look at MAF sensor output. See what ECU thinks engine temperature is. See if emissions system has reverted to closed loop or stuck in open loop.

It’s under $100 if you already have a laptop. You need something like this or you will forever be throwing expensive parts at the problem and not having much success.

The first thing I would do with such a device is check to see what long term fuel trim is on each bank. If it is very high that indicates the system is sending too much fuel to the engine for some reason. It could be as simple as vacuum leak in the intake ducting so that air is bypassing the MAF. The O2 sensors detect a lean condition and start bumping up LT fuel trim to compensate. In the end you can get a rich condition, poor gas mileage and red hot catalytic converts (which may get permanently damaged).

I’d also want to look at engine temperature the ECU sees from the code reader. If the sensor is faulty the ECU may be using the wrong fuel map and sending a very rich mix which isn’t needed. I believe the temp sensor for the dash is different than what the ECU uses.

It could be a stuck open thermostat keeping the car from warming up. That will cause ECU to send rich mix…

It could be a faulty fuel pressure regulator causing pressure to be too high so too much fuel is shot into the ports. The ECU would attempt to correct this though and you’d see LT fuel trim in negative values as the O2 sensors would be saying the mix is too rich.

So it could be many things but you need more data so you can pinpoint the problem better.

All good ideas, unfortunately nothing I can do myself. I've changed the correct temp sensor though, not for the dash but the regular one for the ECU using a genuine lexus one. I had a friend put in a thermostat for me last winter, a lexus original one, and unless he put it in improperly, It might have to be double checked. But the car seems to heat up just fine, I mean the gauge in the dashboard shows it almost to the halfway point, but not really quite a bit less than half. I had a local mechanic check the trim levels for me, and they were off, then put another one off from another LS400 and said the trim levels looked to be fine now, so don't know, maybe I should let my toyota dealer to all the scanning for me, they said it would cost $70.

Maybe a stupid remark, but is the real fuel consumption in accordance with these figures?

The trip computer makes calculations, and there could very well be one bad input into the calculation offsetting everything.

If you calculate the average consumption each time after gas refills, do those figures comply with the trip computer values?

Jac

This is not from a computer. This is from my iPhone application. I just fill the car up all the way, and look at how many miles I had driven since the last fillup and calculate my mileage. I do it by hand too, the app on my phone just helps me keep track and everything. The 96 LS400 doesn't keep track of mpg for you like the newer ones.

Check your wheel alignment. Ask for a before and after printout. The car doesn't have to be pulling one way or the other to be out of alignment. I have fixed many fuel economy concerns by properly aligning all 4 wheels for customers with all makes of Lexus automobiles. What happens is, as the suspension components(ie; ball joints, strut bars, rear trailing arm bushings) wear, the wheels begin to point in the wrong direction as you're driving. When this occurs, it's like you're driving with the brakes applied because it requires more power to overcome the drag caused by the worn steering/suspension.

Just had a wheel alignment done at my toyota dealership. They said the rear was fine and the front was slightly off.

Maybe check as well to see if your brakes are dragging. That would kill MPG too. Go for a 5-10 minute drive on a road where you won't need to brake. Then coast to a stop. Step outside and feel with the palm of your hand if the wheel and brake area is giving off heat (don't touch it as it can get to >>300 degrees). If the brake is dragging it should get good and hot down there.

I thought about this too. I regularly take my foot off the pedal and my LS400 drives forever on its own, almost made me worry about the transmission. I can literally coast forever even if I take my foot off the pedal on a flat road going 40 miles per hour, it just keeps on going and going and going! lol. But will check it as you say just to be sure.

You said you changed the coolant sensor, did you change the right one? There's one for the engine management and one for the dash gauge. here's a link with the procedure:

http://www.clublexus.com/forums/ls400/377171-diy-coolant-temperature-sensor-change-pics.html

If so, have you pulled the plugs to check the color? That should give you an indication if the fuel mixture is too rich.

Had the plugs changed last month at the toyota dealer as part of regular maintenance after changing everything else. Didn't ask the dealer how they looked though. I did notice that the car sounded at least 25% more QUIET after changing the plugs though.

At this point I'm personally thinking there is some problem in the thermostat letting coolant come through, or a major vacume leak somewhere. I appreciate all the replies.

I am almost ready to honestly give up. I'm getting like 11 in the city and 17 combined city/highway. Its ridiculous considering a ford excursion which is probably one of the largest production passenger vehicles ever made is rated 14 in the city. I drive EXTREMELY light footed, grandmas regular drive by me like something is wrong haha.

I've changed both cat converters after check engine light suggested they may be bad. I've changed ALL FOUR oxygen sensors. A mechanic did a scan and told me he thought it was the MAF sensor so changed that. No luck. I changed the spark plugs, no luck. New fuel filter, and new fuel pump after it went bad, still no dice.

New air filter as well, new coolant temperature sensor. New PCV valve. I don't know what hasn't been changed except spark plug wires, but they are only 50,000 miles and 5 years old, and the car runs butter smooth!

The best mileage in a year I was able to get was 25 mpg on a 90 mile trip averaging 50 miles an hour roughly. That was a miracle for this car.

I have read all the links. Its getting quite expensive to drive this car. My only thought is maybe the car isn't getting warmed up enough for the sensors to work, but most people say the LS400 temperature gauge at that one mark before halfway is normal.

I guess the car was cheap and I don't drive much, spending money on parts and diagnosing only adds to the $$$ on top of the fuel I spend. I got the car cheap and I don't drive very much but even an average of 400 miles a month it gets a bit awkward that a 50 mile trip cost $20 bucks in gas when it should cost $10! If its normal then I guess I can live with it , but I'm worried the extra fuel would hurt other components too.

96 LS400 207,000 miles on it. I keep track of the mileage using an app on my iphone, always fill up. Screenshot enclosed.

If anyone who has an ls400 with bad mileage like me who has an idea or someone who can tell me something better than any mechanic has told me it would be appreciated. I want to spent money to change the engine mounts and shocks because everything else has been changed but so tired of spending money on the car that gets horrible mileage like this. I am sincerely thankful to anyone who can brainstorm something for me!

Just a quick update for everyone, I took my LS400 to a local mechanic, has good reviews but a little expensive. He checked the fuel trim levels and said it had a biased lean. After looking around, he said the mass air flow sensor didn't seem right or something like that. There were no codes or anything like that, but he said its possible it was out of calibration etc. We had another LS400 of the exact model that was getting great mileage. Changed the MAF sensor w/the other car and checked the fuel trim levels, and viola, no more biased lean. I didn't want to buy a new one or a remanufactured one, I mean how often do these go bad on a 96 LS400, bought one on eBay for $100, and so far it seems to have helped, fuel trim levels are great. Now I've driven a little bit in the city and the interstate, and the gas gauge is at 3/4 still after driving 80 miles, where usually 80 miles was close to half empty. Let's hope my gas mileage problem is solved!

yah, cars are like doctors, gotta get second opinions

So after changing my lower ball joints and strut rod, went to the shop to get an alignment. The car actually drove great and seemed pretty straight, but the steering wheel seemed a bit off center so thought its best not to take a chance.

Anyway, they called and said the rack and pinion was leaking, and that they couldn't do an alignment, that if they did do an alignment it would ruin the seals and it would gush out power steering fluid.

They said its ok to drive etc, but the alignment was the main issue but that couldn't be done without addressing the rack and pinion issue.

Is there a way to fix a rack and pinion leak without having to replace the entire thing? They said 3 hours of labor and I saw at Sewell Lexus (which is now my favorite place to buy Lexus parts), the rack and pinion was around $380 or so with the forum discount.

Any thoughts on what should I do or did they tell me anything which was incorrect? They said it was a bad leak but my power steering fluid looked full, and I've never seen any leaks on my driveway.

Well, my guy traced the problem. I guess this would benefit EVERYONE who changes the sway bar and/or bushings on their 1995-2000 LS400's due to a squeaking sound. The problem is nothing to do with the actual sway bar bushing, its the bolt that goes through the bushing. Mine was rusted, so that causes the squeak. Took some sandpaper and cleaned the rust off, spread some grease over the bolt and slipped it right back in. Viola! Instantly no more squeaking!

I'm surprised no one ever figured this out. Mechanics will all tell you replace this and that part. If I had known, I might not have even wasted the 200 on sway bars with bushings already pressed in and the money on labor to install it. But my car swayed a ton in the wind and the bushings were cracked so I guess there was some benefit from it.

Otherwise, just getting the bolt out isn't a huge job, clean the rust off of it, slide some grease on it and push it back in and tighten it up. No more squeaking!

Or you can just buy a new bolt from Lexus. Hope that saves someone else some trouble.

It could be swaybar bushings. Mine squeek after a car wash. Humid weather sometimes does it for me. Factory replacement bushings or Moog are rather cheap. Since yours are original you may want to change them anyway but why not when it is doing it shoot some WD40 on them real good and see if it goes away ,,that way you'll know it was them or not. I bought Energy suspension urathane bushings but havent installed them yet and they have grease fittings to boot.

Thanks for your reply. I took it back to the guy who installed it and says it looks like the sound is coming from the new sway bars, he said he would put some lithium grease on them and see if that helps. You wouldn't think that brand new sway bars and bushings would make noise when they get hot like that, I hope some grease helps?

I'll go ahead and change the sway bar bushings. I wish I had bought the original Lexus ones, they were like 11 bucks each at sewell, but 44 plus shipping seemed a bit high so I got MOOGs at rock auto I think it end up costing me like 30 bucks for all 4 if I remember correctly. I thought MOOG parts were even better than oem sometimes, but to my surprise when I got them, they said MADE IN INDIA. Now, they LOOK ok. But had I known to save 18 bucks or so I'd be getting Indian parts, I woulda went ahead with the original Japanese Lexus ones that at least last 10 years, 100,000 miles. But shipping back to Rock Auto and getting a refund and then ordering again from a Lexus dealer is a pain so I guess I'll grease these moog india ones and hope they work fine.

I was going to try some WD-40 but I read online that WD-40 slowly destroys rubber?

Secondly, anyone know why from 95 onwards Lexus doesn't sell Lower Control Arm Bushings separately? The 90-94 models have them. The control arm looks pretty similar, will the lower control arm bushing from a 94 model work on a 96?

I know this is a common topic again and again. So I changed out the lower ball joints, both sides. I changed the strut bars (new bars with bushings already pressed in). Haven't had time to get the alignment done, it drives like a dream now, sharp, feels good, nice and tight like it should, no complaints, no noises (when cold). When I started driving it around and it warmed up some more, the squeeks came back.... On the drivers side. It was on the passenger side before changing all these parts. So I go to the car wash, spray them both down. Voila, noise gone. Drive some more, car warms up again, noise comes back again, this time on the passenger side (going over bumps, into my driveway etc). Pushing down on the front end like anyone would do to check the shocks, and that squeeking noise is there. I go inside a few hours come back and no matter how much I bounce it up and down, that squeeky noise won't come back.

Does anyone know what the squeeking sound could be? I've basically changed everything except the lower control arm and the upper control arm. The sound seems to be coming LOW though and the upper control arm looks great, car drives perfectly. I've read on some other threads it could be the sway bar bushings? The car has 200,000 miles on it and those haven't been changed before, but my local mechanic raised the car on the lift and played with the sway bar trying to push it around and said it was really tight, didn't need changed. So I dunno, sway bar links, sway bar bushings, or possibly the guy who installed my lower ball joints and strut bars didn't do a good job?

Anxiously waiting any expert replies because don't wanna get an alignment done only to find out I need to change something else and have to get another alignment all over again! Thanks.

I know this is a common topic, but I took my car for an alignment today (1996 LS400) to a local alignment/mechanic shop and to inspect a squeeky weird sound I get over bumps and hills. They said both lower ball joints need to be replaced and the lower control arm bushings (said they were "rotted out"). After looking online and on the forums it seems that the lower control arm bushings don't go bad but its actually the strut rod bushings? I guess I'll have to take it to a dealer who understands the suspension but from what I've read here I guess it most likely will be the strut rod bushings and if that is the case, is it just cheaper to change out the entire bar?

Well I contacted Lexus via email and this is the response I received (paraphrased)

"If you would like Lexus to review for possible assistance with repair costs outside of warranty, we ask that you first have your vehicle inspected at a Lexus dealership. Once the dealership has an opportunity to diagnose your vehicle and recommend repairs, you may contact Lexus Customer Satisfaction at 1-800-255-3987, option 3 and we would be happy to review your request further. I apologize, assistance with repairs outside of the warranty period is not guaranteed."

I'm wondering if I can take it to a Toyota Dealer. Driving to a Lexus dealer from where I live would cost a ton in fuel anyway, and they will probably charge just as much to simply diagnose it, and then there is no guarantee they would "assist" anyway. But I have my paper work of dealer complaints, a copy of the TSB, and a LS400 that makes a goose mating call.

I'm sure being a bit insistent might go a long way.

Welp, I think I may have found the problem. There was a TSB released on this in March 1997. This makes me a little angry though because the original owner complained specifically about this noise to an Authorized Lexus Dealer who just excused it off saying they could not pinpoint it or that it was a "normal cooling off sound" (3 times he complained, I still have the paper work to show it). This was in November 1997, WELL AFTER the TSB was released. The problem was never fixed. Now 14 years later I see this TSB. Is there a way to show this TSB to Lexus and have them replace the part? Because the part alone seems to cost $250.

EG003-97

Title:

EVAP CHARCOAL CANISTER NOISE

Models:

'96 LS 400

DATE:

March 7, 1997

Introduction

In some cases 1996 LS 400s may exhibit a slight "buzzing" noise, heard from the EVAP charcoal canister, when the engine is turned off after driving. To minimize this noise, an air chamber has been added to the charcoal canister assembly on 1997 models.

Affected Vehicles

^ 1996 model year LS 400 (UFC20).

Parts Information

Previous Part Number 77740-50042 New Part Number 77740-50043 (although I've read online that this part has also been replaced by 77740-50044)

NOTE: Previous part is fully interchangeable with current part.

Repair Procedure

Replace the Charcoal Canister Assembly on affected vehicles which exhibit this condition.

Ok so the first code I had was P0420 Bank 1, so changed the drivers side cat converter and rear oxygen sensor and t hat code went away, used denso o2 sensor and magnaflow direct fit. Then a day later I get P0430 bank2! Is it right that both of these fail right at the same time, guess I'm going to be changing both catalytic converters?

Ya, I've figured out just as much, good thing its a Saturday, Plan on going back there Monday morning

My catalytic converter on the drivers side went bad, so changed it and the oxygen sensor. I got a direct fit, magnaflow, online for $183 with shipping and everything and a Denso Oxygen sensor for $63 on amazon and installed it myself. The muffler shop took 69 dollars and 3 hours to install the new one.

Heres the problem though. I saw on ebay the old OEM catalytic converters were selling from $80-150 and planned on selling it rather than just leaving it with the muffler shop, BUT THEY WOULDN'T GIVE IT BACK TO ME. They said its law or something and they have to return it to the manufacturer or some bull crap like that, or keep it for 30 days or I don't know, short end of the story they wouldn't budge on giving it back to me, I'm thinking they just wanna get the money out of it themselves.

I live in Illinois. Is there any rule for this or they just !Removed! with me?

I used a denso one for my 96 LS400 and it worked great so far, made in japan, seemed to be as good as the original!

Thanks for the suggestions, will look into the EGR pipe as well

My check engine light came on a few days ago, went to oreilly and got it scanned, P0420 came up, catalytic converter inefficient Bank One something like that.

I looked up some other threads but it appears this code is very ambiguous. I know one thing for sure is, my LS400 is a bit louder than it should be which leads me to think its a leak/bad gasket. I'm also getting HORRIBLE mileage, ie 200 miles per tank. Could it also be an oxygen sensor?

Guess I'm going to have to take it to the dealer but would like to know what to expect so I don't get ripped off so thanks for any replies in advance.

It sounds like your Toyota dealer is looking to talk you into extra,probably unnecessary work on the braking system other than just replacing the fluid.

If you are OK with DIY the procedure is pretty straightforward.

http://www.lexls.com/tutorials/brake/bleeding.html

Thanks a lot, will go for it myself, save some money

My 96 LS400 according to the history of service papers I have, shows the brake fluid has been changed every few years since new.

I noticed now the fluid hasn't been changed in a few years and is quite black. Everywhere I read on the internet, it says its good to change brake fluid ie bleed it out and replace with new.

But my toyota dealer says "he is against replacing brake fluid" just as a maintainence procedure, says he only changes it when changing brake components.

I'm changing all fluids, ie transmission, differential. Don't wanna skip out on brake fluid because I like that honey color. Power steering fluid is fresh and so is coolant.

Should I change the brake fluid no matter what

Welp, got my new fuel pump installed. The denso one, which was made in Japan, got it from autopartswarehouse, found a coupon at retailmenot.com , got it in one day even with regular shipping, like $120 total, works fine!

I'm glad you fixed it, and at such a good price!

I've been having a few problems besides the car not starting and so far, the new fuel pump has changed one major problem I had before.

The car would take FOREVER to warm up, and no one would believe me, but even when the car got warm, if I turned it off for 30 min it went back to full cold.

After changing the thermostat, the car gets warmer faster now, and it stays warmer. How could have putting a new fuel pump fixed this problem? I would have never guessed this as the issue.

Welp, got my new fuel pump installed. The denso one, which was made in Japan, got it from autopartswarehouse, found a coupon at retailmenot.com , got it in one day even with regular shipping, like $120 total, works fine!

Mine was intermittent. If the car doesn't start, its because the fuel pump has gone bad or is going bad so it overheats. You let it sit and it cools and will start working again. Eventually it completely dies out. The only problem is when its working fine then you can't tell what the problem is for sure