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So when an ECU goes bad, what exactly goes bad?

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Old Jun 17, 2009 | 12:53 AM
  #1  
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Default So when an ECU goes bad, what exactly goes bad?

So my ecu went bad. It was giving me white smoke on cold start ups, slow acceleration in closed loop, wasting fuel like crazy....(https://www.clublexus.com/forums/per...mely-rich.html)

When I changed it out to a new one, it completely fixed my problem. I was able to conclude that the ecu was making the fuel injectors go crazy and inject way more fuel than necessary.

Since then, I have replaced all the cylindrical capacitors on the board, and it helped the problem a tiny bit. But its still there.

So what do you guys think? What else could have gone bad?

David

Last edited by sc-driver; Jun 17, 2009 at 11:51 AM.
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Old Jun 17, 2009 | 09:29 AM
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The capacitors can leak out and damage the actual communication pathways in the board.

That what they refer to when people talk about early 1JZ or DSM leaky ecu caps.
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Old Jun 17, 2009 | 11:19 AM
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when I opened up the board there was 0% physical leakage from the capacitors, but I still changed them anyways. Once removed, I thoroughly inspected all around them and they still looked 100% intact.

The board was extremely clean and everything looked brand new. I could not see any signs of damage. What else do you think it could be?

Thanks!
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Old Jun 17, 2009 | 02:09 PM
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Either the capacators as mentioned before or the resistors go bad. There also be a solder that broke a connection. The ECU rebuilders have a test map they use to see what cicuit has the issue.
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Old Jun 22, 2009 | 11:37 PM
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its highly, highly unlikely for the resistors to go bad!http://www.siaelec.com/index.asp?Pag...S&Category=380
This company actually quoted me $195 to diagnose and repair. At that price its cheaper buying a used one from Gazi.

I was thinking about it, and I was wondering would a different type of battery mess up the ecu. Right now my car has a group 35 battery, different then what Lexus originally put in the car. Would this cause something to go bad in the ecu?

This is really troublesome due to their not being any visible physical damage!

What else do you guys think?
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