gp2m

1998 LS400 110k mi.

Starts and runs fine when cold.

Once warm, idles too low, 300-400 RPM, and will die unless either I give it some gas or turn the AC on. No CEL.

Can someone give me some ideas. When I search for my symptoms, I'm just seeing solutions for 1st gen LS400 with the IACV problem. I don't see an IACV on this motor. I've got the TB off now for cleaning. Anything else I should do to adress this problem while the TB is off?

Anyone have this issue on a 98+ vvti 1uzfe or 2uzfe?

Thanks!

skperformance

iTrader: (6)

600-800 , idle up is not working , start by cleaning your throttle

Bill Dowd

If you clean the throttle body and it does't help get ready for a dollar shock i was told my idle position sensor on top of the engine is about $700.00 there is no after market for this part mine is holding but how much longer who knows i will have it replaced with labor about $800.00.

cshurelds

hey man im having the same problem with my 95 ls400 and i just found out it was my throttle positions sensor that is bad i didnt get a code untill i raised my throttle to have the car run at about 800- 1000 rpm after you get a sensor turn it back down so that the car runs smoothly. i got the part at oriley auto parts only $90 buck thats the cheapest i found and had it put on for about $20 or you can do it your self its real wasy only two screws and it right on top of the motor. email if have ques. c_shurelds@yahoo.com

python

iTrader: (4)

vacuum leak will cause this also,otherwise a cel should be on if u have a bad iac or tps. bill dowd what year is ur car cuz someone is filling ur head full of pooooop

GRAND_LS 4

iTrader: (2)

Had a similar issue, you need to clean the throttle body first. You can also tighten the throttle cable on top of the engine to increase the idle slightly. Be careful, you over do it, and it will raise idle too high. It basically tightens the cable as if you were ever so slightly pressing on the gas.

yenanlexus

I have the same year, model, and same problem. I did research on the forum, most car they post is 90-94'. I could not locate TPS and IACV. I am doing research all over. If you have some thing new comming up Please post. thx

yenanlexus

I have 98' ls400 130Kmiles. my car low idle problem. Could any expert outthere post the pic for TPS, and IACV.
Thank you

williamb82

http://www.lexls.com/tutorials/EFI/tps.html

its kinda hard to miss.

McSwine

Thanks, but not the right year model.

williamb82

it shows what the tps looks like and that it is right on the throttle body.

Bill Dowd

1991 ls400 with 240,000 miles

7schulz

Mine had a high idle problem 1800 on cold start up for minutes then 400rpm once warm now that I cleaned the TB and intake plenum with a tooth brush, it doesn't have cold start up issues but still idles at 400 (seems smooth and doesn't die) but idle should be 650+/- so the next step is to adjust the TPS clock wise a hair.

PureDrifter

iTrader: (10)

which is COMPLETELY different for the 98-00 model.

sounds like a vacuum leak, and/or an ECU issue.

yenanlexus

How to test the TPS if it bad?