94 Ls400 Need Ace Troubleshooter Help

[TinyHero1971]

Hi,

Here are the symptoms:

1. Motor will not idle when turned over, can keep motor running by depressing accelerator.

2. TRAC Light always lit, CEL always lit

3. No error codes stored, have reset ECU several times. Again CEL always lit.

4. Can get car to run but VERY slow acceleration.

Have replaced Air Flow Meter 2000 miles ago due to a mechanic saying he got error 31, car ran fine for about 500 miles then began same symptoms.

Do faulty throttle control valves and sensors give fault codes?

or would a MAF sensor throw a code?

Thanks in advance for any insight you can offer, will report back with results.

[Jerry Bransford]

Hi,

Here are the symptoms:

1. Motor will not idle when turned over, can keep motor running by depressing accelerator.

2. TRAC Light always lit, CEL always lit

3. No error codes stored, have reset ECU several times. Again CEL always lit.

4. Can get car to run but VERY slow acceleration.

Have replaced Air Flow Meter 2000 miles ago due to a mechanic saying he got error 31, car ran fine for about 500 miles then began same symptoms.

Do faulty throttle control valves and sensors give fault codes?

or would a MAF sensor throw a code?

Thanks in advance for any insight you can offer, will report back with results.

Does the Lexus engine have an Idle Air Controller as I suspect it does? Mounted on the throttle body, the IAC meters air into the engine at idle when your foot has not opened the butterfly valve via the accelerator pedal. When the IAC valve gets stuck from being dirty, it can cause symptoms 1, 2, and 3. Not sure about symptom #4, have you checked your upstream (closest to the exaust manifold) 02 sensor which when it goes bad, can cause a dramatic loss of performance and fuel economy?

[sbguy]

Hi,

Here are the symptoms:

1. Motor will not idle when turned over, can keep motor running by depressing accelerator.

2. TRAC Light always lit, CEL always lit

3. No error codes stored, have reset ECU several times. Again CEL always lit.

4. Can get car to run but VERY slow acceleration.

Have replaced Air Flow Meter 2000 miles ago due to a mechanic saying he got error 31, car ran fine for about 500 miles then began same symptoms.

Do faulty throttle control valves and sensors give fault codes?

or would a MAF sensor throw a code?

Thanks in advance for any insight you can offer, will report back with results.

Does the Lexus engine have an Idle Air Controller as I suspect it does? Mounted on the throttle body, the IAC meters air into the engine at idle when your foot has not opened the butterfly valve via the accelerator pedal. When the IAC valve gets stuck from being dirty, it can cause symptoms 1, 2, and 3. Not sure about symptom #4, have you checked your upstream (closest to the exaust manifold) 02 sensor which when it goes bad, can cause a dramatic loss of performance and fuel economy?

Also check and see if both coils are good!