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

NEED HELP - 93' Lexus LS400 Issues.

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Old 09-13-24 | 12:51 PM
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Unhappy NEED HELP - 93' Lexus LS400 Issues.

Hello ClubLexus!

I considered that it was time for me to create an account on here after I ended up purchasing a 1993 Lexus LS400 as a project car, the previous owner decided to give me ClubLexus and the LexusOwnerClub referral for questions I had.

After getting the car in my possession I finally dwelled into the forums about the potential issues that I may have within the car. I did end up sending the ECU to someone for board repair after changing the- Fuel pump, fuel filter, oil/filter, air filter and spark plugs. After all of the maintenance was performed I was able to get the car to start running with the assistance of starting fluid until it choked itself out and acted like it didn't get fuel/enough of it. After getting the board back I put it back into the car and it fired right up and idled for about 30 minutes before dying. Shown below is the board after I got it "Repaired" I'm not sure if this is the reason why I am still experiencing (misfires, low power, engine surges, car starts but dies out instantly like it doesn't have fuel.) If this board was shown to be damaged to the level it's at. Then unrepairable, where would i go about getting a new board? Would a Fed ECM work in the CA ECM that's in the vehicle right now?

The plugs did show an extremely rich condition before being changed as well. Timing is correct too!.

The portion of the board that remained burnt/corroded. I am not sure if this is surely the underlying issue of EVERYTHING mentioned.

New Capacitors in place of the old leaking ones.
Old 09-14-24 | 03:31 AM
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Hello, I have a 93 and I had an extreme rich condition to the point where my catalytic converters were red hot I put in a rebuilt denso and make sure it's denso ECU installed that car fired right up took care of all my problems I think this is where you're headed. I think the board itself is damaged in your case and even the new capacitors are not doing the job. The other alternative in my estimation is a company called tannin and they do a quality repair job or can sell you a rebuilt ECU there are too many non reputable companies out there that will sell you a ECU that won't work properly.
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Old 09-14-24 | 07:54 AM
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Originally Posted by widget88
Hello, I have a 93 and I had an extreme rich condition to the point where my catalytic converters were red hot I put in a rebuilt denso and make sure it's denso ECU installed that car fired right up took care of all my problems I think this is where you're headed. I think the board itself is damaged in your case and even the new capacitors are not doing the job. The other alternative in my estimation is a company called tannin and they do a quality repair job or can sell you a rebuilt ECU there are too many non reputable companies out there that will sell you a ECU that won't work properly.
It is the best to replace to the ECU refurbished by Denso.
Old 10-02-24 | 05:06 PM
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Originally Posted by Yamae
It is the best to replace to the ECU refurbished by Denso.
this fixed my issue! I got a denso repaired unit and it fired right up
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Old 10-18-24 | 02:16 PM
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Default Ls400 1996 ls400

Hi Yamae.

Do you know if I may use an alternate ECU to 89661-50303?
1996 LS400 or better just to find exact ECU model number replacement?

I currently have a 1996 LS400 with ECU
89661-50303

Thank you

Last edited by 00LexUS00; 10-30-24 at 04:23 PM. Reason: Can’t locate how to reply to Yamae
Old 10-19-24 | 04:10 AM
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Originally Posted by 00LexUS00
Hi Yamae.

Do you know if I may use an alternate ECU to 89661-50303?
1996 LS400 or better just to find exact ECU model number replacement?

Thank you
What is your current ECU? Is it 89661-50302?
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Old 10-30-24 | 04:25 PM
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Default 1996 ls400 ecu

Originally Posted by Yamae
What is your current ECU? Is it 89661-50302?


I currently have a 1996 LS400 equipped with ECU 89661-50303.
Old 10-30-24 | 06:24 PM
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Originally Posted by 00LexUS00
I currently have a 1996 LS400 equipped with ECU 89661-50303.
Then you can use an ECU 89661-50303.
There is a way to use an improved one 89661-50340 after the heavy modification. The evaporation system was updated and the modification needs some good skills and knowledge to do the job.
Old 10-31-24 | 02:06 AM
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Default Ecu

Originally Posted by Yamae
Then you can use an ECU 89661-50303.
There is a way to use an improved one 89661-50340 after the heavy modification. The evaporation system was updated and the modification needs some good skills and knowledge to do the job.
Thank you so much. I’ll look for both ECUs for the future.
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