Suneet

How does replacing the motor mounts and tranny mounts change the ride characteristics? What are symptoms of bad mounts? It seems to me like all they would do is make the car vibrate at standstill.. I wish my car handled the bumps and imperfections on the road like it used to.

lorenzo816

BG cleaner, In my opinion, does do some good. But so does a good scrubbing.
I did BG 3 years ago.

If you feel like taking off the intake and the manifold, be my guest.
I would wait until there is a reason to get in there, like a starter replacement.
Unless you're one of those tuner dudes that want to tweak some hp wherever you can get it.

And I didn't search 4 it yet, but how easy is it to check/replace the mounts?

Bradster

is the way to go as i stated in my earlier post my experience on several vehicles i have owned all of which had the original motor mounts has been that upon replacing them is that the car at idle is so much smoother..no vibration thorough the steering wheel..of course we assume your vehicle is tuned up well...the old mounts had 1/2 or less the amount of rubber left on them when compared to the new...new mounts more rubber..greater deterent to the transmission of vibrations...replacing all 3 mounts on the LS400 should take 30-40 minutes but i'm sure the book time is greater..not a difficult job.

Suneet

You were able to replace the engine mounts and transmission mounts yourself? What special tools did you need? How much did the parts cost?

Bradster

I didn't mean to give the impression that i did the work myself...local shops do the heavy lifting for me the ballpark figure for the 3 mounts is about 150.00 or so.

Och

iTrader: (3)

Do you know if I test the MAF resistance while the car is running or not? Because when I test it when the car is not running, the resistance is right around 2.53, while the temperature is ~65-70. However, when I turn the car on, the resistance drops to ~1.53

lspower

so if i pull the ecu fuse and disconnect my maf. i will have a new car? could i just do it once just to try or will it messup my car ? thanks also. you pull ur efi fuse before u goto the trac why?
thanks

Och

iTrader: (3)

Update:

Now that my car is pretty much put back together after being stolen, I am back on trying to solve the acceleration issues. Last time I ran it with MAF disconnected was back in September, when outside temperatures were still in the 80ies. Now that outside temperatures are in 30-40ies, the MAF trick no longer works too well. Yes, the car has much more power with MAF disconnected, but the engine pings like hell, especially in the upper RPM range. I've searched this forum and SC400 forum, and it seems that a lot of people are suffering from lack of torque, but noone has a definite solution, so now I am on a mission to get to the bottom of this, however I am not a mechanic, and my knowledge about engines, air/fuel ratio, etc is pretty limited. So far whatever I did to my car, seem to be changing parts from good to new. For those who don't remember my original posts, let me just refresh everyones memory.

1) Throttle body removed and completely cleaned - solved idle issues, but the car still has not low end torque

2) Fuel filter replaced - no improvement

3) PCV Valve cleaned - no improvement

4) Full tune up including new distributor rotors, caps, wires, spark plugs - car became a bit smoother, but no increase im power.

5) Numerous fuel injection cleaners ran trough gas, including Seamfoam, Marvel Mystery Oil, Chevron, and Lucas - no avail.

6) Two full seamfoam threatments, gas, crancksase and intake chamber - no improvement.

And then my car got stolen and stripped, and I spent all this time trying to put it back together, and right now I am back to trying to work out the problem with no torque. So far I replaced addition parts:

1) Both main oxygen sensors - guess what, no improvement

2) Throttle position sensor - no improvement

So today I tried something else. There is a fuel pressure regulator, right next to the throttle body, connected to the throttle body with a thin vacuum hose. I disconnected that hose and took the car for a drive.

HOLLY CRAP!!! The car had almost as much torque as my GS430. Give it full throttle and didnt chirp tires, it spun them like mad. I got it in a long empty block, gave it full throttle, and it spun the tires for half the block, until about 4000 RPMs, scarrying the living crap out of bypassers and putting a huge smile on my face.

Needless to say I was happy like a pig in a dumpster, thinking that I finally got to the bottom of it. Not so fast. After about ten minutes of driving the car became even slower than it was with the hose connected and the engine would ping like mad with increasing RPM. So I hooked the hose back on, and the car is now pretty much back to her old self. So now I'm like wtf!? If anyone has any idea, please, your input is welcome.

HKSC430

Dude, you seem to have done a lot of good to your car. Lexus V8s are known to be excellent engines in terms of power, quietness, and fuel economy when in good shape.

Maybe it's time to take a step back and think in simple terms. For there to be power, you need combustion inside the combustion chamber. You need the right amount of fuel and air delivered to it. A 'spark' at the right moment causes the mixture to burn creating power. The computer and sensors govern when, what, and how much. That power is delivered via the drivetrain to the wheels.

So, any problem fouling up the above perfect scenario causes the Lexus engine to run bad (loss of power and fuel economy) or less perfectly (ping).

-is combustion chamber clean, and free of carbon deposits?
(likely, with all that cleaning)
-is some other fluid fouling up the combustion? e.g. power steering fluid from the faulty power steering idle up valve or engine oil from blown gaskets?
-is the compression ratio same for all 8 cylinders? (old age/high mileage wear)
-is the right amount of fuel and air delivered?
-are the computer and sensors connected and functioning normally?
(O2 sensors, MAF sensor, other sensors (temperature)?, proper connection to the spark plugs and injectors)
-has the computer gone nuts?
-is something blocking fuel delivery? (fuel filter already replaced)
-is something blocking air delivery?
-is something blocking the exhaust?
-is the ignition system right? (seems so, with all that replaced)
-is the timing right? (did you ever replace the cam belt and problems came?)
-is something rusting or corroding away along the fuel delivery system? (unlikely in Lexus)
-is something robbing the engine power? (worn water pump, alternator, steering pump, and/or air conditioner compressor)
-is the power not delivered to the wheels? (transmission, rear differential)
-are you running on bad fuel long term?

You really need to have sixth sense as to where the problem(s) is/are, or just swap parts with normal Lexuses to experiment. There could be more than one problem with age and mileage, or perhaps just a small one. Regardless, the Lexus engine should run perfectly in the car manual posted octane in normal conditions.

References:
http://www.lexls.com/tutorials/

P.S. If you solve the problem, thank the guy in the references- not me.

Och

iTrader: (3)

Replaced drivers side ignition coil. No avail.

I'm getting sick and tired of dumping money into this POS, I thought Lexus were suposed to be reliable.

lorenzo816

This guy is right. It has got to be something simple. And I would have never done anything to the MAF sensor. Thats just crazy. Its an element that measures air as it passes through it. So cleaning it and whatver you did.... is just going to screw it up in my opinion. You got your car jacked and stripped right? Thats def not good. I wouldn't suspect my car would run right after that too.
Check the lines, something may be pinched. This happened to me on a different car as the mechanic was trying to rape me over and over. Lucky I found it. Bastard.
...anyhow...
Well, either you can stand back and figure out what is wrong with it, pay a specialist to fix it or I'd part it out. Too bad your LS is letting you down.
Its not cheap to own one of these but why would you want to drive anything else?

B.Diddy

iTrader: (1)

Man, I have tried to diagnose my car, but it seems futile. I think I am just going to swap a 4.3L from a 2000+ LS430 into this car and call it a day. Its gonna take quite a bit to clean up the brittle vacuum hose mess that is in these cars. I'll give it a shot when the weather gets warm though. but I will eventually remove this V8

Thermactor

iTrader: (1)

It's a 12 year old luxury car. Imagine how much more time and money you'd need to spend on a '94 740iL. Ouch.

Och

iTrader: (3)

But this is downright killing me. I mean, everything seems to be intact, yet something isn't. I'm probably going to end up taking it to a diagnostics place and have them check it out - but before I do that, I'm going to do the EGR delete mod.

HKSC430

Okay, so not ignition coils, but good to have new ones.
What is the engine and car like now?

Probably you are complaining of poor power (and fuel economy?) still?
Please fill us in on the situation.

-Does the car start perfectly like all Lexuses and idle smoothly now?

-If no, what do you hear?

-When you floor the gas at idle, does the engine run smoothly?

-If no, what do you hear?

-Are you losing and topping up certain fluids regularly?
(oil, power steering fluid, coolant- suspect leak into engine)

-Get someone to floor the gas for you, do you hear something, smell something or see smoke from the exhaust?

-Drive it around, what's that like?

-Are the temperature gauge readings normal?

-Does the car run at the right gears appropriately the whole time?

-Errrrrrrr, did someone drop a screw inside one of the cylinders? not unlikely

Hey, 100,000k the engine block should still be in pretty good shape.
Keep up the good spirits.
Going through logical thinking helps, even when you get an expert.