azari

Hi guys, I'm new here. I just purchased a 1991 LS400 with 72000 miles on it from the original owner. It's a great car and I love it. Not being very familiar with lexus vehicles (and vehicles in general) I have a question for you. When the car is in gear (Drive) and stopped with my foot on the pedal, as I start to take off and accelerate I feel a slight hesitation (split second) when RPM needle reaches around 1200-1300. This is the only time I feel the hesitation and for the rest of the drive there is no more hesitaion. In other words, it happens only when I accelerate from a complete stop at around 1200-1300 RPM. Is this normal? Do you all experience this with your first generation LS400s or is this a problem? Please let me know, thank you. my email address is armanazari7@yahoo.com in case you want more detailed description of what happens. Again, thanks alot.

95ls400

sound like you may need a engine tune up

Lvangundy

This has been discussed MANY times. Alot of LS owners have seen this problem, myself included. It doens't seem like there is one part to replace that fixes this issue, it's more like a combination of misc parts and fluid flushes that remove the hesitation.

The easy stuff to replace are the things to look for first. Try replacing the air filter with a new toyota air filter. Don't look at K&N filters - specifically the cone type. They have been noted to take away horsepower and torque in the LS400.

If you are mechanically inclined you can try cleaning the thottle body (past the butterfly valve) with a rag and some throttle body cleaner spray at the same time you change the air filter. Much easier after you have 25% of the parts removed when you change the air filter. Cleaning the TB has also been discussed and you may want to use the search function to find more info.

Other things that can be done include -
-flushing the transmission fluid (toyota type-IV - not dexron)
-engine tune up (spark plugs, caps, rotors, and wires)
-flushing the differential fluids
-throttle position sensor replacement (a $90 part)

There miht be some other things other CL members have discovered about this problem, maybe more people will respond.

Hope this helps and welcome to CL!

azari

Lvang,

Thanks for the info. I was thinking that since sooo many owners have noticed this, it might be that the car was built this way and that's the way it's supposed to run. I guess we should ask an owner who had bought the car new and see weather or not he remebers any hesitations from the very beginning (when the car was driven off the dealer lot). Last night i went through the old threads and found your post on the RPM decline during rolling acceleration. That also happens to me, but it's not really that noticable and you'd have to keep your eyes on the tachometer. Have you found any soulutions for this one? or is it the way the car supposed to be? Another thing, when I turn the steering wheel, I hear a whining noise which gets louder as I turn more. I think it's the steering pumb, and if so, what's happening in there and how can I fix it, and for how much?
Thank again

Lvangundy

The hesitation problem can be fixed /greatly reduced if you do those recently mentioned maintenance items.

About your PS grind noise, this can be fixed by adding more PS fluid. The car specs say Dexron II automatic transmission fluid for the PS fluid refill. You can also use off the shelf 'power steering fluid.'

Be aware that there is an issue with the PS steering reservoir / pump and the rack and pinion leaking. My car for example has a slow leaking rack and pinion, but no PS pump / reservoir leak.

You can fill the fluid for now, but check to amke ysure you don't have a PS or rack & P leak.

GA400

Welcome to the Club! I also have a 91 ls400, but mine has a few more miles (210,000+)

I also had this problem and mine was remedied by;

Replaced air filter.
Adding good fuel injector cleaner at every oil change (B-12 was what I used the first time, Chevron is also very good from what I read, and I have switched to Chevron now).
Using an oil additive called engine restore (not sure if this helped or not, but it has helped some other cars in our family and it has been around a very long time).
Transmission and rear end fluid flush and replace with Toyota OEM fluids.

Good luck and let us know what you try and what results you get!

GA400

azari

Thank you both. I have a couple more questions. First, if I were to completely fix this problem once and for all, I'd have to probably replace something. What would that be? and HOW MUCH would it cost? 2nd, GA400, you mentioned a fuel injector cleaner, how do you apply this? (do you pour it somewhere? rub it, ??) thanks

azari

BTW, my first question refers to the power steering problem.

Lvangundy

You would want to take your car to a shop and have them check the rack and pinion unit. There are two rubber boots on each side which may crack/tear and develop leaks. That's the situation with mine.

There is also a power steering rebuild kit which replaces all the seals on the P/S pump. You can get this from Carson toyota or your local Lexus dealer. Beware they might try to get you to buy a new P/S pump unit and reservoir, this is up to you.

GA400

The fuel injector cleaner is poured into the gas tank. I usually add mine when I am down to a 1/4 tank or less and I am at the gas station to fuel up. Pour in the cleaner, add the gas on top of it, and it cleans the entire fuel path from the fuel pump to the injectors as you drive. Again, don't bother with el cheapo fuel injector cleaner, treat your Lexus to the good stuff!

GA400

azari

hey guys,
If my front corner lamp (for 1991 LS400) does not work, will I have to buy a single bulb and put it in or will I have to replace the whole unit which looks like this---> http://www.*****************.com/cgi...121559LAS.html
?? This is for driver side BTW. thanx.

brian3268

Abcedefghij

azari

Hi everyone,

I'm sure most of you are familiar with the illumination problem of the speedometer/tachometer on the first generation lexus LS400's (you know, how the outer portion of it fades and etc.). I was wondering weather or not setting the brightness of the speedo/tacho would have an effect on its longevity. In other words, if I set it on low or high brightness, will I be able to prevent or even delay this problem? (or sooner or later it'll come to me and everyone else). BTW, is there anyone who is running on the original illuminator set and has not experienced any fading? if so how many miles on your car? ( i have 73000 miles and nothing yet).
Thanx in advance