What Happened to my ECU!!!

[AWD_FIEND]

POST VIRGIN!!!

What the hell happened to my ECU?!

Here's the backround info. My 1G 92 GSX wouldnt start one day after sitting for ~3 weeks and it was acting like it was out of gas. The fuel gauge was reading full empty so I suspected someone syphoned my fuel (getting more common where I am)! So I put 5 gallons in, still no start. I suspected the fuel pump next so I pulled off the fuel return hose to verify the rail was dry and sure enough no fuel. So I checked the MPI fuse it was good, pulled the MPI relay and bench tested it, it checked out so the only other likely issues were the fuel pump, or the computer. No way it was the computer the car was just running, caps were replaced, and the car was just sitting in my garage no way something could have shorted and damaged the ECU. So I figured it must be the fp, espcially when I jumped the test wire and still didnt get fuel. So I bought a fresh pump (it needed it anyway) installed it...car still didnt run. I said to hell with it pulled the computer cracked it open and ! Never seen a burn like that before on an ECU that did nothing but sit in a garage. Anyone else experience a similar failure, or have any suggestions as to what could have caused this?

 

[snowborder714]

Blown ISC driver.
driver01 [ECMTuning - wiki]

 

[AWD_FIEND]

Did the driver blow or did something in the wiring short it out, that's what has perplexed me because the wiring doesnt look disturbed and its wrapped in fresh loom and e-tape.

 

[AWD_FIEND]

Just followed the link disregard my previous question. Great info thanks. Any suggestions on how to test what caused the short?

 

[snowborder714]

Check the ISC resistance. You can find more info from the VFAQ page.

 

[AWD_FIEND]

This is for anyone else reading this thread. I more thuroughly researched this issue after snowboarder714 pointed me in the right direction, and discovered this damage was caused by a faulty idle speed control motor (ISC). The link in his first reply explained a lot about why this occured. I encourage you to read it thurouhly even if you dont have an noticeable idle problem. My car idled perfectly, but when the ISC shorted it damaged my computer to the point it's irrepairable (in my case). Learn from my misfortune and test your ISC often.

 

[Rob10_99]

Wow that thing poped big time. When your ISC is going out or doesn't work, my suggestion is just unplug it so this can't happen.
When its vibrating back and forth, that's generating heat, that goes on long enough and it melts the insulation on the coils inside the ISC, poof you just shorted the ISC Driver in your ecu. It doesn't like that.

 

[Hubbell91Tsi]

that is pretty bad but im seen worse on 3si .

 

[AWD_FIEND]

I've learned a lot through this process, thanks for all your help and info. What's really weird is I didnt have any warning. The car ran awesome, smooth idle, great at cruise, then the very next time I tried to start the car it wouldnt turn over. It seems to have spontaneously combusted! But now that I'm better informed I hope I'll be able to avoid such a costly setback in the future. Actually during my research I read that the max current these chips are rated for is 2amps so I was contemplating installing a couple 2amp fuses in line to help prevent another melt down like this. Anyone try that, or find any issue with the concept?