saleenssc

98 Ls400
160K miles

over the last few weeks ive noticed the acceleration has been getting sluggish. This is most noticble when accelerating from a stop, or when accelerating to pass. The best way to describe it is that the throttle response is not as instant anymore. It seems to bog down for a second before the power really kicks in. Ive also noticed the idle is around 450 RPM with a/c off in D4. With a/c on around 650 RPM. Ive been reading alot on this site and it seems like my spark plugs could be an issue. I am unsure when they were last replaced. My best bet would be they have nearly 100K miles on them. I am ordering NGK IFR6T-11 plugs and also a new PCV valve and grommet. Anything else i should be considering to replace.

thanks

RA40

iTrader: (6)

TPS is a possibility. Check the slack in the throttle cable too.

dicer

When did they go to throttle by wire?

Yamae

I assume your idea will be improving the acceleration some but not fully. I don't think your idle would be improved by that.

My bet is 2 other different items that cause your problem rather than yours. But I'd better not interrupt you and I dare wait until your result will come up before insisting my bet. Since 100k miles sure is the time to change spark plugs and the grommet. You have been reading the site a lot and you might have already noticed those 2.

billydpowe

iTrader: (1)

yep I am thinking with Yamae, one of the girls on here done a very nice write up on this issue, just do a little searching..

Scraape

It seems the 5-speed transmissions up shift very early in these cars, put your car in PWR mode and see if the acceleration improves

PureDrifter

iTrader: (10)

Assuming car is otherwise maintained (spark plugs done very 90k) then clean the throttle body, it will likely help.

saleenssc

with car off the throttle cable has some slack in it. How can i tell if its normal or needs adjustment.

thanks

saleenssc

Yes car has always been maintained. However its been nearly 100K since the plugs have been changed according to my records. Ive already ordered new ones and they will be replaced soon. I cannot recall the last time throttle body was cleaned. But i will certainly put it on my checkilist of things to address soon.

thanks

saleenssc

i drive in PWR mode 100% of the time. same symptoms in NORM and PWR

thanks

saleenssc

I did find this interesting thread:

https://www.clublexus.com/forums/mai...ntial-fix.html

anyone have any experience with these Fuel injection cleaners ? Do they work ? any chance they do more harm than good ?

Legender

I would start with the simple things that may need to be addressed anyways. If spark plugs are old then replacement is due. As well, the PCV and grommet and hose are easy items.
My own experience, with my now replaced 95, was low idle after long stretches on the highway... so low that it would die when I came to a complete stop. It would start right up no problem. Replacing the plugs and a thorough cleaning of the throttle body resolved my problem. The TB can get pretty sticky and gummed up in there and it needs to be cleaned out on a regular basis. After I completed those two items, my low idle issues went away completely.
Just my experience, yours may differ.

Scraape

I doubt they make any difference. You'd be better off buying cleaned and flow tested injectors or sending your current ones to be cleaned.

I changed my fuel filter and my car accelerates so much better, I also did a diff drain and fill, idk if that would help

PureDrifter

iTrader: (10)

maintain before anythihng else.

Tonyucf20

I had the same issue with my 98. Cleaned out the throttle body and MAF and it was good to go