help! - 1996 LS400 will not give codes
Thread Starter
Lexus Champion
Joined: Dec 2011
Posts: 4,078
Likes: 87
From: Birmingham, AL
help! - 1996 LS400 will not give codes
my 1996 LS has a couple of issues:
started to run a little rough after long drives, then recently has been starting up with very high idle when cold, Idle starts out at 1600 then slowly climbs to about 2200 or so then falls immediately back to 1600 and cycle repeats - never seems to come down and straighten out - I can't find or hear any vacuum leaks.
even when running right, gauge temp has always been down at about 1/8 (1/2 way between cold and first mark) - but gas mileage isn't horrible or anything, but not outstanding, either
cleaned throttle body - looked at MAF sensor, the sensor looks clean, didn't clean it - throttle body cleaning did not solve high idle.
tried 3 different known-good OBD-II scanners, always get communication error or link error - cannot retrieve codes!
changing out engine temp sensor (but not gauge temp sender) and thermostat tonight, hoping that helps, will report back - I may also seafoam it!
update: with new coolant temp sensor and thermostat, no more high idle, when cranked, idled at 600, and got progressively lower, then I drove it for about 10 minutes, and now it will not idle at all - and I have to hold down accelerator to get it to start - also check engine light just came on, but still cannot pull codes
my questions:
1. do 1996 LS ECU's fail much? - Is it capacitors or a bad solder joints issue that I can fix myself? - thinking about pulling it out and taking a look at the circuit board for burned or leaking caps.
2. does the 1996 LS400 use that Karmann Vortex sensor that you are not supposed to clean, or a hot wire system that is OK to clean with the CRC MAF sensor cleaner? (it has that intake thing in the center that looks like a plastic jet-engine)
started to run a little rough after long drives, then recently has been starting up with very high idle when cold, Idle starts out at 1600 then slowly climbs to about 2200 or so then falls immediately back to 1600 and cycle repeats - never seems to come down and straighten out - I can't find or hear any vacuum leaks.
even when running right, gauge temp has always been down at about 1/8 (1/2 way between cold and first mark) - but gas mileage isn't horrible or anything, but not outstanding, either
cleaned throttle body - looked at MAF sensor, the sensor looks clean, didn't clean it - throttle body cleaning did not solve high idle.
tried 3 different known-good OBD-II scanners, always get communication error or link error - cannot retrieve codes!
changing out engine temp sensor (but not gauge temp sender) and thermostat tonight, hoping that helps, will report back - I may also seafoam it!
update: with new coolant temp sensor and thermostat, no more high idle, when cranked, idled at 600, and got progressively lower, then I drove it for about 10 minutes, and now it will not idle at all - and I have to hold down accelerator to get it to start - also check engine light just came on, but still cannot pull codes
my questions:
1. do 1996 LS ECU's fail much? - Is it capacitors or a bad solder joints issue that I can fix myself? - thinking about pulling it out and taking a look at the circuit board for burned or leaking caps.
2. does the 1996 LS400 use that Karmann Vortex sensor that you are not supposed to clean, or a hot wire system that is OK to clean with the CRC MAF sensor cleaner? (it has that intake thing in the center that looks like a plastic jet-engine)
Last edited by LScowboyLS; Dec 20, 2011 at 05:01 AM.
Driver
Joined: Jan 2011
Posts: 157
Likes: 0
From: ca
my 1996 LS has a couple of issues:
started to run a little rough after long drives, then recently has been starting up with very high idle when cold, Idle starts out at 1600 then slowly climbs to about 2200 or so then falls immediately back to 1600 and cycle repeats - never seems to come down and straighten out - I can't find or hear any vacuum leaks.
even when running right, gauge temp has always been down at about 1/8 (1/2 way between cold and first mark) - but gas mileage isn't horrible or anything, but not outstanding, either
cleaned throttle body - looked at MAF sensor, the sensor looks clean, didn't clean it - throttle body cleaning did not solve high idle.
tried 3 different known-good OBD-II scanners, always get communication error or link error - cannot retrieve codes!
changing out engine temp sensor (but not gauge temp sender) and thermostat tonight, hoping that helps, will report back - I may also seafoam it!
update: with new coolant temp sensor and thermostat, no more high idle, when cranked, idled at 600, and got progressively lower, then I drove it for about 10 minutes, and now it will not idle at all - and I have to hold down accelerator to get it to start - also check engine light just came on, but still cannot pull codes
my questions:
1. do 1996 LS ECU's fail much? - Is it capacitors or a bad solder joints issue that I can fix myself? - thinking about pulling it out and taking a look at the circuit board for burned or leaking caps.
2. does the 1996 LS400 use that Karmann Vortex sensor that you are not supposed to clean, or a hot wire system that is OK to clean with the CRC MAF sensor cleaner? (it has that intake thing in the center that looks like a plastic jet-engine)
started to run a little rough after long drives, then recently has been starting up with very high idle when cold, Idle starts out at 1600 then slowly climbs to about 2200 or so then falls immediately back to 1600 and cycle repeats - never seems to come down and straighten out - I can't find or hear any vacuum leaks.
even when running right, gauge temp has always been down at about 1/8 (1/2 way between cold and first mark) - but gas mileage isn't horrible or anything, but not outstanding, either
cleaned throttle body - looked at MAF sensor, the sensor looks clean, didn't clean it - throttle body cleaning did not solve high idle.
tried 3 different known-good OBD-II scanners, always get communication error or link error - cannot retrieve codes!
changing out engine temp sensor (but not gauge temp sender) and thermostat tonight, hoping that helps, will report back - I may also seafoam it!
update: with new coolant temp sensor and thermostat, no more high idle, when cranked, idled at 600, and got progressively lower, then I drove it for about 10 minutes, and now it will not idle at all - and I have to hold down accelerator to get it to start - also check engine light just came on, but still cannot pull codes
my questions:
1. do 1996 LS ECU's fail much? - Is it capacitors or a bad solder joints issue that I can fix myself? - thinking about pulling it out and taking a look at the circuit board for burned or leaking caps.
2. does the 1996 LS400 use that Karmann Vortex sensor that you are not supposed to clean, or a hot wire system that is OK to clean with the CRC MAF sensor cleaner? (it has that intake thing in the center that looks like a plastic jet-engine)
Thread Starter
Lexus Champion
Joined: Dec 2011
Posts: 4,078
Likes: 87
From: Birmingham, AL
has anyone had the experience of not being able to read the codes on a 95-97 LS400 - did it turn out to be the ECU or a wiring problem to the OBD-II port or was it a grounding problem? (ECU needs very reliable ground for correct communications)
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philllyj
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Jul 23, 2012 08:07 PM
