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

Extremely rough idle and lots of mechanical noises - resetting computer solved it

Old 06-12-14, 10:16 AM
  #1  
Finn
Driver
Thread Starter
 
Finn's Avatar
 
Join Date: Nov 2013
Location: Finland
Posts: 183
Likes: 0
Received 1 Like on 1 Post
Default Extremely rough idle and lots of mechanical noises - resetting computer solved it

Cheers all!

OK, here's what happened:

Last Saturday I pushed my -91 out from the garage - pushed did not start - to make room to work on my Harley. After few hours I was done and I started the engine and drove said 15 feet back in. Engine was running slightly faster idle when I shut the engine off.

Today I went in the garage to take LS out. I started it and it did not start as it usually starts with ease but...well...differently. I noticed immediately that the idle was very, very rough and there seemed, well, that's what it felt, to be all sorts of mechanical noises. I shut the engine off almost instantly.

After a while I started it again and it was slightly better but not what it should be. I listened to the engine idling and reversed the car out and shut it off.

Something in the back of my head told me to reset the computer and I pulled battery cable off and let it sit for a while. I then put the cable back on and started the car. Most of the roughness and such were away and I went for a ride. Now after 20 miles or so computer seems to have re-learned and 1UZ-FE purrs again smoothly. With a tick-tick but smooth nevertheless.

QUESTIONS:

What exactly happened on Saturday when I shut the engine off in fast idle? Was it in some sort of warm-up phase that messed up the computer?

If I had not reset the computer today would it have learned and cleared the situation by itself?
Old 06-12-14, 02:57 PM
  #2  
timmy0tool
Moderator
iTrader: (7)
 
timmy0tool's Avatar
 
Join Date: Sep 2008
Location: 714/949, SoCal
Posts: 6,927
Received 415 Likes on 370 Posts
Default

have you had your ECU capacitors changed?

i don't like starting a car just to move it a few feet then shutting it back off especially when cold. i like to keep the car running for at least 5 minutes for the oil and fluids to circulate. this is where the most wear and tear happens on your engine.
Old 06-12-14, 05:56 PM
  #3  
sha4000
Lexus Test Driver
iTrader: (1)
 
sha4000's Avatar
 
Join Date: Aug 2005
Location: N.Y.
Posts: 6,853
Received 334 Likes on 288 Posts
Default

Probably did not give the alternator enough time to recharge the battery correctly. I'm with timmy on this one, I also let the car run until it's at least warmed up before shutting it down.
Old 06-12-14, 08:21 PM
  #4  
Finn
Driver
Thread Starter
 
Finn's Avatar
 
Join Date: Nov 2013
Location: Finland
Posts: 183
Likes: 0
Received 1 Like on 1 Post
Default

I don't like starting the car for 15 feet either but that was a must - now I know better ie. either let it idle longer or take it for a spin.

We do not seem to have ECU capacitor problem on this side of the pond. Never heard anyone mentioning that here. Mine - apart from this hickup - works like a dream.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
LVPUNK
LS - 3rd Gen (2001-2006)
13
03-17-24 04:38 AM
MattLS400
LS - 1st and 2nd Gen (1990-2000)
190
03-18-21 03:28 PM
lovetheIS
IS - 2nd Gen (2006-2013)
6
11-16-16 12:45 PM
piamill
CT 200h Model (2011-2017)
1
01-19-13 08:54 PM
v8pwr
LS - 1st and 2nd Gen (1990-2000)
12
03-05-02 01:54 PM


Thread Tools
Search this Thread
Quick Reply: Extremely rough idle and lots of mechanical noises - resetting computer solved it



All times are GMT -7. The time now is 07:51 PM.