All LS400 owners with bad gas mileage READ THIS!
11-23-13, 01:16 AM
#181
I hope the people reading this thread have thick skins:
What is wrong with some of you guys? I have a '93 LS400 and it is a wonderful car - but you must put in the time and effort to enjoy it.
It only takes an hour or so to read this thread through. Read it. Read the other threads. Try all the suggested fixes - ok, that takes longer. But really, these are nice old cars that drive like a dream - but all old cars insist that either you or your well paid mechanic become intimate with tham on a regular basis.
I've changed two of the three coolant temp sensors (and now my coolant temp gauge is low so I replaced the T-stat but no change - that means I should change the coolant gauge temp sensor). I changed the two rear 02 sensors - good results. I changed the tranny fluid and installed a tranny fluid cooler before finding out my ignition rotors and wires were the problem with the 'bucking' under accelleration.
I had a mechanic diagnose and replace the ECU ($500)(apparently with a used one) only to have it fail a few years later. So, I had it rebuilt with the new caps ($200) (whatever - not an electronics guy) so now all is well three years later.
I replaced the instrument cluster ($500 - Lexus) only to have it fail 25,000 miles later. Had it rebuilt by some guy in CA - so now all is well 50,000 miles later.
The Nakajima amplifier in the trunk failed, slowly over two years, and stunk the car up so bad I thought I would have to sell it. Pioneer to the rescue for $500 plus my effort replacing the speakers - do not reuse the sub-woofer in the rear deck lid - it sucks and is the wrong ohms - all is well - and I have Blu-tooth and a USB port for the Ipod/smart phone.
BTW - replace the radio antenna with a power boosted unit super-glued to the rear window up high - huge improvement. Leave the old antenna in place and down to prevent water ponding in the drivers side rear wheel well - that will stink up your car as well.
Contact the wheel company in CA and swap your rims for hard chromed ones - again - $500. Please don't mess up the suspension geometry with the wrong aftermarket wheels.
Had the leaky rear main engine oil seal replaced (again $500) only to learn the guy set the new one exactly in the same groove as the old one (if you do this don't drive the seal all the way to the stop - offset it at least 1/8 inch to the rear) - guess what, still leaks - daaauuummmnnn - now I run oil level at half full and made a nice tampon holder to catch the leaking oil - change the tampons once a month.
The rear struts got so bad I had them replaced (not the air shock version - if you have those you are screwed). Good results.
The exterior paint and interior leather (with minor nicks and wear) are in great condition - although the drivers side seat gets a little firm after an hour or so. The original floor mats are in excellent condition.
Do not argue with the wood trim pieces on the arm rests when the adhesive releases and they warp up - drill little holes and put in little screws to hold them down front and back (with epoxy or similar adhesive underneath) - paint the screw heads brown to match.
Replace the weak hood lift struts with the cheap aftermarket struts you can get off Ebay - just have to work with them a bit to make them fit.
If your coolant fan shroud plastic cracks, reglue it with gorilla glue - tape it in place and slather the glue on the broken bosses - the intake air duct hides the mess anyway. The sad thing: still on the original coolant hoses...
Keep the plastic underliner in place under the engine - these cars had a very low CD when they were new - that underliner helps.
My wife loves this car. I could buy her a new one tomorrow for cash but she doesn't want it.
Windshield 20 years old? Replace it and use those high dollar single piece windshield wipers - they last three times as long.
Ok, thats about it - did I mention the 'shrimp sandwitch?' My apologies to Forrest Gump.
I pay liability insurance only. The taxes are nothing. MPG is about 16 - 22+
I just got back from flogging this biotch up and down the Smokey and Blue Ridge Mts - passing most of the traffic up and down - 700+ miles - in the rain - less than two tanks of gas.
Like what you just read? Like the way she drives? Learn her. Care for her. Enjoy her.
What is wrong with some of you guys? I have a '93 LS400 and it is a wonderful car - but you must put in the time and effort to enjoy it.
It only takes an hour or so to read this thread through. Read it. Read the other threads. Try all the suggested fixes - ok, that takes longer. But really, these are nice old cars that drive like a dream - but all old cars insist that either you or your well paid mechanic become intimate with tham on a regular basis.
I've changed two of the three coolant temp sensors (and now my coolant temp gauge is low so I replaced the T-stat but no change - that means I should change the coolant gauge temp sensor). I changed the two rear 02 sensors - good results. I changed the tranny fluid and installed a tranny fluid cooler before finding out my ignition rotors and wires were the problem with the 'bucking' under accelleration.
I had a mechanic diagnose and replace the ECU ($500)(apparently with a used one) only to have it fail a few years later. So, I had it rebuilt with the new caps ($200) (whatever - not an electronics guy) so now all is well three years later.
I replaced the instrument cluster ($500 - Lexus) only to have it fail 25,000 miles later. Had it rebuilt by some guy in CA - so now all is well 50,000 miles later.
The Nakajima amplifier in the trunk failed, slowly over two years, and stunk the car up so bad I thought I would have to sell it. Pioneer to the rescue for $500 plus my effort replacing the speakers - do not reuse the sub-woofer in the rear deck lid - it sucks and is the wrong ohms - all is well - and I have Blu-tooth and a USB port for the Ipod/smart phone.
BTW - replace the radio antenna with a power boosted unit super-glued to the rear window up high - huge improvement. Leave the old antenna in place and down to prevent water ponding in the drivers side rear wheel well - that will stink up your car as well.
Contact the wheel company in CA and swap your rims for hard chromed ones - again - $500. Please don't mess up the suspension geometry with the wrong aftermarket wheels.
Had the leaky rear main engine oil seal replaced (again $500) only to learn the guy set the new one exactly in the same groove as the old one (if you do this don't drive the seal all the way to the stop - offset it at least 1/8 inch to the rear) - guess what, still leaks - daaauuummmnnn - now I run oil level at half full and made a nice tampon holder to catch the leaking oil - change the tampons once a month.
The rear struts got so bad I had them replaced (not the air shock version - if you have those you are screwed). Good results.
The exterior paint and interior leather (with minor nicks and wear) are in great condition - although the drivers side seat gets a little firm after an hour or so. The original floor mats are in excellent condition.
Do not argue with the wood trim pieces on the arm rests when the adhesive releases and they warp up - drill little holes and put in little screws to hold them down front and back (with epoxy or similar adhesive underneath) - paint the screw heads brown to match.
Replace the weak hood lift struts with the cheap aftermarket struts you can get off Ebay - just have to work with them a bit to make them fit.
If your coolant fan shroud plastic cracks, reglue it with gorilla glue - tape it in place and slather the glue on the broken bosses - the intake air duct hides the mess anyway. The sad thing: still on the original coolant hoses...
Keep the plastic underliner in place under the engine - these cars had a very low CD when they were new - that underliner helps.
My wife loves this car. I could buy her a new one tomorrow for cash but she doesn't want it.
Windshield 20 years old? Replace it and use those high dollar single piece windshield wipers - they last three times as long.
Ok, thats about it - did I mention the 'shrimp sandwitch?' My apologies to Forrest Gump.
I pay liability insurance only. The taxes are nothing. MPG is about 16 - 22+
I just got back from flogging this biotch up and down the Smokey and Blue Ridge Mts - passing most of the traffic up and down - 700+ miles - in the rain - less than two tanks of gas.
Like what you just read? Like the way she drives? Learn her. Care for her. Enjoy her.
12-19-13, 06:52 PM
#183
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hey guys,sorry i've been off the grid.i've finally saved up some cash and am going to try the suggestions given.i am first going to refit the missing condenser fans.i couldn't source a used unit from the breakers and a new one is too pricey so i am taking the aftermarket route,i found 2 new 12 inch panasonic condenser fans and am going to fit them and see if it makes any difference.will update on how this goes later.fingers crossed and hoping really hard that this reduces the temp problem at least a little.
also,i followed the tutorial on lexls.com on reading the check engine light and my car is throwing 6 fault codes.code 24,31,21,28,63,67.code 24 is the intake air temp sensor signal and code 31 is the air flow meter signal.from the research i have done,i found that the intake air temp sensor is embedded in or is a part of the afm.is this true?i can source the unit from a breaker but am wondering can this be causing my car to run rich?as mentioned earlier the car runs perfectly fine albeit the higher than normal temp and rich afr but doesnt lack in power or sputters or anything.it runs perfect.should i still change the afm or could the code be interrelated?
i'm pretty sure now that the real culprit to the car running rich is the 2 main o2 sensors on the left and right bank,codes 21 and 28 respectively but wont be changing these yet as they are kinda expensive.will get this done next time round.do you reckon i should still get a new radiator cap and thermostat?i was thinking of doing this next after the fans are fitted.
lastly,for codes 63 and 67,i wont be changing the solenoids just yet until i have resolved the rich afr and high temps as the shifting isnt too bad at this point.just one question on this,for code 67 which is the OD direct clutch speed sensor signal malfunction,is this a faulty solenoid as well?i haven't a clue.
thanks again guys,will update on the fans and the difference soon.tc
also,i followed the tutorial on lexls.com on reading the check engine light and my car is throwing 6 fault codes.code 24,31,21,28,63,67.code 24 is the intake air temp sensor signal and code 31 is the air flow meter signal.from the research i have done,i found that the intake air temp sensor is embedded in or is a part of the afm.is this true?i can source the unit from a breaker but am wondering can this be causing my car to run rich?as mentioned earlier the car runs perfectly fine albeit the higher than normal temp and rich afr but doesnt lack in power or sputters or anything.it runs perfect.should i still change the afm or could the code be interrelated?
i'm pretty sure now that the real culprit to the car running rich is the 2 main o2 sensors on the left and right bank,codes 21 and 28 respectively but wont be changing these yet as they are kinda expensive.will get this done next time round.do you reckon i should still get a new radiator cap and thermostat?i was thinking of doing this next after the fans are fitted.
lastly,for codes 63 and 67,i wont be changing the solenoids just yet until i have resolved the rich afr and high temps as the shifting isnt too bad at this point.just one question on this,for code 67 which is the OD direct clutch speed sensor signal malfunction,is this a faulty solenoid as well?i haven't a clue.
thanks again guys,will update on the fans and the difference soon.tc
12-19-13, 06:58 PM
#184
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hi luischaves,sorry for the late reply.i am just getting around to the problem and am going to try the suggestions posted here.i will let you know what resolves the matter.stay tuned.and yes,even i drive really slow at this point and get shocking mpg.one question,do you have the oem condenser fans at the front?is there 1 or are there 2 fans in your config?
01-15-14, 11:27 PM
#185
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so i replaced mine on my 90 LS400
pretty simple, only difficult thing was putting on the plastic piece right above the sensor.
i didnt take off the driver side spark plug cover only passenger
i did this in the dark, and honestly id give the difficulty a rating of 3/10 (real easy, only difficult thing is pulling everything and putting it back together without losing a screw)
took me maybe ~1hr ??
didnt pay attention to my gas mileage before i changed it but only knowing it goes down QUICK, after i took it for probably 20-30 mile drive and gas needle stayed pretty close to before i took the drive.
ill report gas mileage after i empty my tank n refill knowing how many gallons is in the tank!
pretty simple, only difficult thing was putting on the plastic piece right above the sensor.
i didnt take off the driver side spark plug cover only passenger
i did this in the dark, and honestly id give the difficulty a rating of 3/10 (real easy, only difficult thing is pulling everything and putting it back together without losing a screw)
took me maybe ~1hr ??
didnt pay attention to my gas mileage before i changed it but only knowing it goes down QUICK, after i took it for probably 20-30 mile drive and gas needle stayed pretty close to before i took the drive.
ill report gas mileage after i empty my tank n refill knowing how many gallons is in the tank!
01-16-14, 08:51 AM
#186
Pole Position
this is a great thread, i just bought a '94 LS400 and I'm going to change the thermostat, radiator cap, gauge sensor, engine coolant temperature sensor.....as well as fuel filter and pcv valve.....also the mass air flow sensor is going to be cleaned as well as the throttle body.....THANKS EVERYONE!
01-16-14, 09:34 AM
#187
Lexus Champion
do NOT use any cleaners or solvents on the mass air flow sensor (AFM) on a pre-95 LS400, you will ruin it - a soft new chamois cloth and very low pressure dry compressed air ONLY
01-16-14, 09:39 AM
#188
Lexus Champion
the rear (downstream) O2 sensors have no effect on how the car runs, they are there as emissions "tattletale" sensors only - the upstream sensors (pre-cat) are the ones that the ECU uses to make fuel trim and other decisions
01-20-14, 07:47 AM
#189
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hi guys,i have fitted the 2 condenser fans that were missing with a couple of generic Panasonic fans,been testing the car and sadly there's no drop in temperature at all.did a few back to back tests with the fans on and off and surprisingly there's not even a little drop in temperature.it still hovers above the center line. any idea what could be causing this?
01-20-14, 09:11 AM
#190
Lexus Champion
if the fans you fitted are performing like the originals, then it's likely that the fans were not the problem in the first place, there are at least 10 reasons a car can run hot that have nothing to do with the electric fans!
such as:
● blown head gasket
● bad thermostat
● bad gauge sender (appearance of running hot, but not really running hot)
● bad fan clutch (on models with conventional fan)
● bad hydraulic fan or low fan fluid (on models with hydraulic fan)
● clogged/blocked condenser fins (common and usually due to mud or bugs or a plastic bag)
● clogged/blocked radiator fins
● internally clogged radiator (must be replaced, cleaning does not do much)
● A/C refrigerant overcharge
● insufficient coolant in cooling system or not a high enough % water (should be 50% water, 50% Toyota red long life coolant)
● excessive air in cooling system
● bad radiator cap (usually causes too low of temp though, rather than too high)
● bad electric fan sensor in bottom corner of radiator (this is a common reason for running hot!)
● bad fan relay
such as:
● blown head gasket
● bad thermostat
● bad gauge sender (appearance of running hot, but not really running hot)
● bad fan clutch (on models with conventional fan)
● bad hydraulic fan or low fan fluid (on models with hydraulic fan)
● clogged/blocked condenser fins (common and usually due to mud or bugs or a plastic bag)
● clogged/blocked radiator fins
● internally clogged radiator (must be replaced, cleaning does not do much)
● A/C refrigerant overcharge
● insufficient coolant in cooling system or not a high enough % water (should be 50% water, 50% Toyota red long life coolant)
● excessive air in cooling system
● bad radiator cap (usually causes too low of temp though, rather than too high)
● bad electric fan sensor in bottom corner of radiator (this is a common reason for running hot!)
● bad fan relay
Last edited by LScowboyLS; 01-20-14 at 09:27 AM.
01-20-14, 05:49 PM
#191
Driver School Candidate
Any suggested source for JASVIN's front sensors? Maybe cheap aftermarket? Better than nothing?
01-20-14, 06:01 PM
#192
Lexus Champion
01-20-14, 10:00 PM
#193
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Temp Sensors
Hey Guys
In the water bridge between the two sides are TWO sensors 1 with just one wire , that is Gauge. the other has two wire connector that is for ECU,. Both are very reasonable to renew with Good quality
Toyota parts just shop around.... I got mine from TrueBlue Auto parts with free shipping and quick service online ..... Stay out of places like Auto Zone for these cars ; you will not be happy with the Crap they want you to buy and neither will your car. It costs you very little more for real Quality parts
In the water bridge between the two sides are TWO sensors 1 with just one wire , that is Gauge. the other has two wire connector that is for ECU,. Both are very reasonable to renew with Good quality
Toyota parts just shop around.... I got mine from TrueBlue Auto parts with free shipping and quick service online ..... Stay out of places like Auto Zone for these cars ; you will not be happy with the Crap they want you to buy and neither will your car. It costs you very little more for real Quality parts
06-23-14, 11:34 PM
#195
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Yup The sensor that talks to the Computer is very important to be correct because if it "says" the engine is still cold it will ALWAYS run rich !!!! It will cause your mileage to suffer and Driveability too if the car always runs rich !!