Well Ive noticed this problem with my 2000 LS400. Im not sure if it is normal or not? It seems to idle kinda high between 850 - almost 1000 when it park. And then it seems to idle rather low in drive ranging from 200 - 400. So you guys know how to adjust my idle speed? or what could be the cause of this?

Here are some pictures.

In park


In gear

 

Also one other thing I notice is when I let off of the accelerator when going over 45mph. The rpms will start to drop and right when it hits about 1000rpms it downshifts and then the rpms raise up to about 1200. Is that normal aswell or no?

 

A good place to start would be to look for a vacuum leak.

 

How would I go about checking for a vacuum leak???

 

if you have to ask, take it to a shop you trust.

im thinking either vacuum leak and/or a dirty throttle body.

 

^^^ This is what I'd look at. Sometimes it could be hard to find a vacuum leak b/c of ALL the vacuum lines on the engine. Doing a Seafoam treatment might help you out.

 

Where can I find a 98-00 TB Cleaner DYI?

 

https://www.clublexus.com/forums/ls4...ls400-faq.html

 

Throttle. Got a good mechanic?

 

...And that's why I have a mechanic I can trust.

 

You guys need to follow this, it worked for me like a charm. I had a serious idle problem making the LS shut off when I came to stop. Not anymore!
I cleaned my TB and MAF sensor today with the help of the posted F.A.Q thread PD posted.
CL rocks!

 

Cleaned my 1995 LS4000 TB today as it was idling about 1100 in park. Still idles high, pulled the plug on the MAF car quit and the CEL came on. Reconnected the MAF, cleared the CRL and the idle dropped to normal. Any suggestions what to do if she idles high when I fire it up tomorrow? I've heard disconnecting the battery may reset the computer but that sounds far fetched. Any help is greatly appreciated.

 

Disconnecting the battery and pressing on the brakes to drain any remaining current should indeed reset the ECU and clear out all the long term learned values.

Stan

 

Good idea to go ahead and clean the MAF sensor when you do the throttle body. You can buy MAF sensor clearer at almost any autoparts store.

 

Is the air filter clean? Cheap enough to replace.

Stan