1996 Lexus Ls400 idle/shift issue?
03-25-18, 05:21 PM
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1996 Lexus Ls400 idle/shift issue?
I need some help! I haven’t owned my Lexus long so my knowledge isn’t extensive.
I was driving home and power mode was on and a yellow light came so I kinda pushed through it. After I had slowed down I was getting no throttle response until pedal was nearly floored then it’d hit hard as if it was in overdrive. I’d slow down again and once again no throttle response until nearly floored then bam it’d haul. I got home and parked and the idle fluctuated to around 400 then bounce to 1000 and back down repeatedly. Today I went out and turned it on and it kicked right on, no idle issue, and I drove around my apartment complex and no issue. Have no idea what happened. Has this occurred to anyone else?
I was driving home and power mode was on and a yellow light came so I kinda pushed through it. After I had slowed down I was getting no throttle response until pedal was nearly floored then it’d hit hard as if it was in overdrive. I’d slow down again and once again no throttle response until nearly floored then bam it’d haul. I got home and parked and the idle fluctuated to around 400 then bounce to 1000 and back down repeatedly. Today I went out and turned it on and it kicked right on, no idle issue, and I drove around my apartment complex and no issue. Have no idea what happened. Has this occurred to anyone else?
03-25-18, 05:59 PM
#2
I need some help! I haven’t owned my Lexus long so my knowledge isn’t extensive.
I was driving home and power mode was on and a yellow light came so I kinda pushed through it. After I had slowed down I was getting no throttle response until pedal was nearly floored then it’d hit hard as if it was in overdrive. I’d slow down again and once again no throttle response until nearly floored then bam it’d haul. I got home and parked and the idle fluctuated to around 400 then bounce to 1000 and back down repeatedly. Today I went out and turned it on and it kicked right on, no idle issue, and I drove around my apartment complex and no issue. Have no idea what happened. Has this occurred to anyone else?
I was driving home and power mode was on and a yellow light came so I kinda pushed through it. After I had slowed down I was getting no throttle response until pedal was nearly floored then it’d hit hard as if it was in overdrive. I’d slow down again and once again no throttle response until nearly floored then bam it’d haul. I got home and parked and the idle fluctuated to around 400 then bounce to 1000 and back down repeatedly. Today I went out and turned it on and it kicked right on, no idle issue, and I drove around my apartment complex and no issue. Have no idea what happened. Has this occurred to anyone else?
03-26-18, 01:05 AM
#3
That's right. First things first. Change ECU capacitors.
Old capacitor. All electrolytic capacitors with non-solid electrolyte age over time,
due to evaporation of the electrolyte. The capacitance usually decreases and the equivalent series resistance (ESR)
usually increases. The normal lifespan of a non-solid electrolytic capacitor of consumer quality, typically rated
at 2000 h/85 °C and operating at 40 °C, is roughly 6 years. It can be more than 10 years for a 1000 h/105 °C capacitor
operating at 40 °C. Electrolytic capacitors that operate at a lower temperature can have a considerably longer lifespan.
Just an idea.... old and leaking ECU capacitors might be the culprit. Common problem with the LS400.
● Lexus LS400 - 1990-2000 (in 1997 and earlier models, the problem is extremely common)
https://www.clublexus.com/forums/ls-...capacitor.html
SYMPTOMS:
Please understand that any one of these symptoms can be a sign of ECU capacitors beginning to fail. - You do not need all or most of them to have this issue!
Your ECU capacitors are strongly suspected if you have at least one of the following intermittent issues on your Lexus or Toyota:
● problems in getting into diagnostic mode or scanner says "no communication"
● random dropping into "limp home" mode
● weird shifting problems
● OBD port is unresponsive, seems dead
● throwing random fault codes
● engine won't rev out/rev limits at 2000 or less rpm
● engine runs like crap, then suddenly runs fine again
● random not starting or cutting out
● low idle or erratic idle
● often very hard to start, requires starting fluid
● transmission will not automatically shift, only manual shift is possible
● transmission jerks from 1st to 2nd gear, and kinda slips from 2nd to 3rd
● no A/C compressor operation
● idle speed rolling up and down, or sometimes too low and sometimes too high
● speedometer not working reliably
● speed (cruise) control not working
● tachometer not working sometimes
● air bag light flickering intermittently
● A/C going into reset with flashing front defog light (front defog light typically flashing 10 times)
● check engine light on sometimes, but no codes stored, often in concert with ECT light
● ECU not communicating with scanners or not displaying codes with jumper installed
● bad sulfur exhaust smell in concert with not running right above
But before that, diagnose faulty parts and get rid of those OBD-trouble codes you have already stored.
21 - main O2 sensor & heater signal
27 - sub O2 sensor signal
28 - main O2 sensor
29 - sub O2 sensor
31 - air flow meter signal
71 - EGR system malfunction
Old capacitor. All electrolytic capacitors with non-solid electrolyte age over time,
due to evaporation of the electrolyte. The capacitance usually decreases and the equivalent series resistance (ESR)
usually increases. The normal lifespan of a non-solid electrolytic capacitor of consumer quality, typically rated
at 2000 h/85 °C and operating at 40 °C, is roughly 6 years. It can be more than 10 years for a 1000 h/105 °C capacitor
operating at 40 °C. Electrolytic capacitors that operate at a lower temperature can have a considerably longer lifespan.
Just an idea.... old and leaking ECU capacitors might be the culprit. Common problem with the LS400.
● Lexus LS400 - 1990-2000 (in 1997 and earlier models, the problem is extremely common)
https://www.clublexus.com/forums/ls-...capacitor.html
SYMPTOMS:
Please understand that any one of these symptoms can be a sign of ECU capacitors beginning to fail. - You do not need all or most of them to have this issue!
Your ECU capacitors are strongly suspected if you have at least one of the following intermittent issues on your Lexus or Toyota:
● problems in getting into diagnostic mode or scanner says "no communication"
● random dropping into "limp home" mode
● weird shifting problems
● OBD port is unresponsive, seems dead
● throwing random fault codes
● engine won't rev out/rev limits at 2000 or less rpm
● engine runs like crap, then suddenly runs fine again
● random not starting or cutting out
● low idle or erratic idle
● often very hard to start, requires starting fluid
● transmission will not automatically shift, only manual shift is possible
● transmission jerks from 1st to 2nd gear, and kinda slips from 2nd to 3rd
● no A/C compressor operation
● idle speed rolling up and down, or sometimes too low and sometimes too high
● speedometer not working reliably
● speed (cruise) control not working
● tachometer not working sometimes
● air bag light flickering intermittently
● A/C going into reset with flashing front defog light (front defog light typically flashing 10 times)
● check engine light on sometimes, but no codes stored, often in concert with ECT light
● ECU not communicating with scanners or not displaying codes with jumper installed
● bad sulfur exhaust smell in concert with not running right above
But before that, diagnose faulty parts and get rid of those OBD-trouble codes you have already stored.
21 - main O2 sensor & heater signal
27 - sub O2 sensor signal
28 - main O2 sensor
29 - sub O2 sensor
31 - air flow meter signal
71 - EGR system malfunction
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