LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

Low Idle issue resolved! '00 LS

Old 05-13-07, 10:07 AM
  #1  
lexusnutt
Intermediate
Thread Starter
 
lexusnutt's Avatar
 
Join Date: Sep 2005
Location: SC
Posts: 407
Received 36 Likes on 22 Posts
Smile Low Idle issue resolved! '00 LS

I finally got my car back from the dealer for the infamous low idle issue. They replaced the throttle body (luckily under warranty). When I picked it up, it still had the same problem . Low idle at 400 RPM unless the lights or A/C was on. Upset that they released it to me without confirming it was fixed, I returned it to them and firmly asked that they resolve the issue. 2 days later (and a ES350 loaner ), they said the contacted a Lexus engineer and found that the ECM had to be reprogrammed for the new throttle body. There was no TSB on it and that's why it took so long to diagnose.
Well, needless to say it worked! The idle remains at 700 RPM no matter what the condition is. Throttle response is also MUCH better. I'm a happy camper as it now runs perfectly! I imagine a through cleaning of the TB will work, but the reprogramming was the key in my case.

Cheers!
Old 05-14-07, 08:26 AM
  #2  
GRAND_LS 4
3UZ-FEEEE
iTrader: (2)
 
GRAND_LS 4's Avatar
 
Join Date: May 2004
Location: Northern VA
Posts: 6,251
Received 17 Likes on 12 Posts
Default

Wow, thats great news. Hopefully it will stay that way. I had the same problem with my 98LS400, and now with my GS. Strangly, my current LS430 with the same engine doesnt seem to have that problem.
Old 05-14-07, 08:10 PM
  #3  
skperformance
Lexus Champion
iTrader: (6)
 
skperformance's Avatar
 
Join Date: Nov 2002
Location: Mississauga,Ontario,Canada
Posts: 3,488
Likes: 0
Received 8 Likes on 8 Posts
Default

Mine does idle low under the same situations of no a/c .
I never changed my throttle body since i have owned it and only happened last summer. Also my throttle body is clean though.
Old 05-14-07, 08:18 PM
  #4  
PureDrifter
BahHumBug

iTrader: (10)
 
PureDrifter's Avatar
 
Join Date: Aug 2004
Location: California
Posts: 23,918
Received 94 Likes on 86 Posts
Default

thats wierd, i constantly drive it w/o AC and i idle around 500-700 depending on the weather.

glad to see ya got it fixed
Old 05-15-07, 12:37 AM
  #5  
Broker404
Driver

 
Broker404's Avatar
 
Join Date: Jan 2006
Location: Atlanta, GA
Posts: 159
Received 0 Likes on 0 Posts
Default

My 99 LS idles around 400 after it's warmed up... what's wrong with a low idle? the engine performs fine.
Old 05-15-07, 12:48 AM
  #6  
PureDrifter
BahHumBug

iTrader: (10)
 
PureDrifter's Avatar
 
Join Date: Aug 2004
Location: California
Posts: 23,918
Received 94 Likes on 86 Posts
Default

Originally Posted by Broker404
My 99 LS idles around 400 after it's warmed up... what's wrong with a low idle? the engine performs fine.
400 is low,iirc recco'd idle is 650+/-100rpm.

can lead to electrical issues, esp. if u have a dead/dying battery (alternator isnt putting out enough voltage), heavy steering, and the car bogging down when accelerating from a stop.
Old 05-15-07, 09:46 AM
  #7  
lexusnutt
Intermediate
Thread Starter
 
lexusnutt's Avatar
 
Join Date: Sep 2005
Location: SC
Posts: 407
Received 36 Likes on 22 Posts
Default

What was strange is that when it was under electrical load (i.e. lights on) the idle would go up. (Always ran great at night). I had cleaned my TB also but with limited results as it would seem to revert back after a day or so. What I found interesting is that after the new TB was installed, the condition was the same until after I returned it and they reprogrammed the ECU/ECM.

The stealer told me that TB's can go bad....something about the throttle plate sticking and that a mild cleaning won't do much good. You would have to disassemble most of it to get to the areas that would cause the sticking. Right.

Grand, it's possible that the TB issue was resolved with your car (430), even though it's the same motor. I truly feel that this is a common issue with these cars that Lexus is not admitting... just too many of us having this problem....

PD, your right about the ramification of having a idle thats too low. The difference in throttle response is HUGE...no hesitation whatsoever
I didn't realize what a major impact it could have on performance. I actually thought I was saving gas with a lower idle. I probably was because now I find myself stomping on the gas now to pass all the bimmers!
Old 05-16-07, 04:38 AM
  #8  
GRAND_LS 4
3UZ-FEEEE
iTrader: (2)
 
GRAND_LS 4's Avatar
 
Join Date: May 2004
Location: Northern VA
Posts: 6,251
Received 17 Likes on 12 Posts
Default

Originally Posted by lexusnutt
What was strange is that when it was under electrical load (i.e. lights on) the idle would go up. (Always ran great at night). I had cleaned my TB also but with limited results as it would seem to revert back after a day or so. What I found interesting is that after the new TB was installed, the condition was the same until after I returned it and they reprogrammed the ECU/ECM.

The stealer told me that TB's can go bad....something about the throttle plate sticking and that a mild cleaning won't do much good. You would have to disassemble most of it to get to the areas that would cause the sticking. Right.

Grand, it's possible that the TB issue was resolved with your car (430), even though it's the same motor. I truly feel that this is a common issue with these cars that Lexus is not admitting... just too many of us having this problem....

PD, your right about the ramification of having a idle thats too low. The difference in throttle response is HUGE...no hesitation whatsoever
I didn't realize what a major impact it could have on performance. I actually thought I was saving gas with a lower idle. I probably was because now I find myself stomping on the gas now to pass all the bimmers!
It seems like the programming of these TB's and ECU's have changed over the years. I've taken my car to be checked out at the local dealer, and they say its perfectly fine. I told them it wasn't, and even shot a video of the low idle issue, and they still maintain their stand. I'm guessing its a problem Lexus has not issued a TSB on, and dealers aren't always inclined to try and fix problems they presume minor in the engine's operation.

It is very true that running your lights will resolve the idle issue... I've also noticed the low idle issue to be more evident when its humid/hot outside.
Old 05-16-07, 07:55 AM
  #9  
lexusnutt
Intermediate
Thread Starter
 
lexusnutt's Avatar
 
Join Date: Sep 2005
Location: SC
Posts: 407
Received 36 Likes on 22 Posts
Default

You (they) are right, there is no TSB. That's why they had to place a call to Lexus engineering. TSB's affect their reliability ratings. Why would they do that?!

The dealer also originally told me that everything was OK, that the tach was off! I laughed at him and told him that was impossible due to the change during load. I wrote a 2 page letter to the manager describing my frustration, telling them that I don't care how long I had to leave the car, but I wanted it fixed. An apology from the SM and 2 days later, it was resolved.

I will try to find our exactly what programming was done and post. If we communicate exactly what the issue is to them, they hopefully have no choice but to fix it. My dealer was very cognizant of the impending survey that was to come my way from corporate!

Personally, this was a very important fix as the overall performance of the car is enhanced besides the idle increase.

Cheers!
Old 04-15-09, 02:09 PM
  #10  
396chevy
Rookie
 
396chevy's Avatar
 
Join Date: Apr 2009
Location: Houston TX
Posts: 31
Received 15 Likes on 10 Posts
Default

So did you ever find out what exactly they reprogrammed? i think my 2000 is doing the same thing apprently the TB was replaced under warrenty a while ago, i just got the car, and it seems slow right off the line once it hits about 30 watch out its quick! is this normal i know they dont get to the rated torque till higher rpms but what exactly does the torque curve look like? thanks!
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
hypervish
RX - 1st Gen (1999-2003)
8
10-16-11 10:03 AM
Mega
LS - 1st and 2nd Gen (1990-2000)
6
01-21-11 04:29 PM
LexusGS400
Performance
22
04-21-10 08:29 PM
dudematt
LS - 1st and 2nd Gen (1990-2000)
10
10-02-08 03:33 AM
TGRich
Performance & Maintenance
3
03-05-05 08:27 PM


Thread Tools
Search this Thread
Quick Reply: Low Idle issue resolved! '00 LS



All times are GMT -7. The time now is 06:06 PM.