91LS400LEX

I have been wanting to get my throttle body cleaned for awhile now, but put it off. The dealer wanted like $120! I took it today to a shop that has about 6 mechanics (been around for years) and always stays busy. The guy that did it (older man) had a 1991 ES250, so we talked alittle about Lexus's, because I stayed in the shop as he did it. Hes not really up not up to par though, because he dont think an LS400 was made in 1990 and it started in 1991 and that in 1990 that it was a ES300. I just let him believe it, but we all know 1989 was the first year the LS400 was sold as a 1990 model.

My throttle body was terrible. It was all gummed up. It took him about 30 minutes to get it cleaned out, but he did and man, does it run so much better. That hesitation when I would first accelerate from a stop is gone, as is the "chugging" that I was getting on light acceleration between 35-50 mph as the grades changed.

After that, I ran more errands... pleased with the performance. Also another miracle (though it may be short-lived) is that when I slowed down off of the highway before I got home is that I noticed the steering seemed to be easy to turn... I pulled into my driveway and my power steering is back again! Even when in gear and stopped, I could steer with my pinky for the first time in about 6 weeks. Most of you know the nightmares I have had with my power steering lately. I am wondering if after I cleaned the pump screen that there was air in the lines? Apparently the screen was dirtier than I thought. I just hope it continues to work and not go back out. Its been a strange ordeal thats for sure.

skperformance

iTrader: (6)

Increased vac assist from a clean throttle body is making the power steering work .

lexondubs

ive been wanting to clean mine out but just haveent lol

91LS400LEX

Thanks SKP

Do it, you will be amazed if it has not been cleaned in awhile. After watching this mechanic do it, I am sure I could have done it myself.

deanshark

I cleaned mine when I changed the valve cover gaskets, seeing how it had to come off anyway. It was gunked up at least 1/16". So bad I had to use a scraper on it, with cleaner. I only drove it a couple hundred miles b/f I did ALL the other work I did, but I can tell the BIG difference on the take off power. Well worth the time. This past owner didn't take care of the car like it should be, but now that I got it it will be.

sakataj

iTrader: (182)

we been doing this lately in the gs 2nd gen section. i did mine man its awesome....not for performance wise for me but increased mileage was my perk. went from mid 16/17's to mid 18/19's in the city with the v8. easily coulda done yourself though OP and saved the $

what part of tn u in OP?

91LS400LEX

Northeast Tennessee is where I am.

Oh yeah, I can tell a huge difference... even my transmission is shifting better (smoother)!

ALL of that hesitation and stumbling is GONE! There was even a point where I thought my torque converter was bad because of the lurching... it was all the throttle body causing it.

On a less happy note, I spoke too soon on the steering, because when I left for work this morning it was back to its old ways. I never went to the way it was before again today. I guess something is really screwed up with the steering pump or rack. I am not sure. Its like a switch is being thrown on the steering.

Thermactor

iTrader: (1)

I wanted to tell you that much but I thought that it would be easier for you to find out on your own. I'm sorry

91LS400LEX

lol. Yeah, the PS system on this car has been the most annoying thing I have ever dealt with. Its crap.

JimsGX

Would this apply to the brake booster too?

skperformance

iTrader: (6)

It will increase vac to all associated parts. If it i is sluggish again it is better but still needs more cleaning . Best way it to disconnect the PS vac line and run some throttle body cleaner through it .

91LS400LEX

Isnt it ironic? Power steering worked perfectly today.

Am I a fool to not be able to figure this out?

It doesnt matter. I may be selling it on Tuesday anyway.

sksbutterf

I've owned a 1999 LS400 for nine years and had the problem of hesitation on acceleration the whole time.. I've had it at the dealer for this problem a couple of times. They never could find anything wrong. Of course, being a woman they problem didn't believe there was a problem. I came across the suggestion of having the throttlebody cleaned here on the forum, printed the info out and took it to them. Amazingly they cleaned the throttlebody and the car runs better than it's ever run.

I think this forum is great!

cndnate

aww you're buttering us up

fixmiester

Okay, I'll bite: Do you believe that the slight change in manifold vacuum would actually effect a major change in the PS pump pressure? Most comments about eliminating the "usually leaking" ACV valve results in barely noticeable change in steering performance. To think it could make the pump totally ineffective would be a bit surprising, IMO.