Sorry for the quality of the last pic..

Its a 88 CRX, obd1 converted using Blown90hatch's harness, all wiring was soldered and heat shrinked. Setup has worked excellent for almost 2 years. p28, Uberdata.

Car sat for about 5 days in very damp weather while i was doing some work to it.

Last night i went to the gas station.. Filled up, got back in, it started up and died, solid CEL, and smoke came from the ecu within seconds. I pulled the positive cable and towed it home..

Opened up the ECU and found that.. The area of damage is clear, Is that a capasitor?

What would cause this to happen.. Bad grounds maybe.. I only had it running about 5 min when i got to the gas station before this happened. I DID forget to tighten the grounds for the tailights (had that section unpluged for painting) and the battery ground (in the trunk) isnt the greatest.

Another ECU isnt the problem... Its finding the cause.

Any idea's?

TYIA!

 

I have seen that before, in more than just ECUs. It looks like the input filter capacitor shorted internally, and caused extreme heating to that localized area. I doubt that there is an issue with your car, you are just dealing with a 10+ year old piece of electronics. I generally replace all of the electrolytic capacitors when any of them look questionable during the chipping process.

 

Thankyou!

I will pick up a p06' from a local wreckers for free and convert it to P28 using my old parts (everything else seems to be fine)

And hopefully that will save me some cash.

 

HamiltonRex asked me to take a look at this, so here goes. Without close up in focus, pix of both sides of the board, I can't 100% tell you what happened.

That said, what I can say is you experienced a dead short failure. What we call in the business a Cat I, i.e. catastrophic. When you see traces vaporized, it is a dead give a way. The traces are a better fuse, than the fuse, especially if it is a 15 or 20 amp fuse.

The first thing I would look for is FOD. Foreign Object Damage. A loose nut floating around, a screw, a solder ball. These boards are conformal coated, typically clear polyurethane. That's just a fancy word for clear insulating "varnish" or "paint."

Now if you tell me no loose nuts fell out, or acorns, or walnuts, I would look at the components near your lightning strike. The first thing I see is a **gasp** electrolytic capacitor! Heaven help us, what newb EE speced that one? Electrolytic caps and 20 year service life do not go hand in hand. Electrolytics have a nasty failure mode. As they age, they dry out and loose capacity. In an environment with healthy dV/dT they start to get warm. The warmer they get, the drier they get, the hotter they get, the less capacitance they have until they bake to a crisp, and sometimes that fragile Al2O3 punches thru, and wham you have a direct short. Which could be very similar to what you see.

I prefer to use tantalum caps with circuitry to limit their power on dV/dT, or better yet monolithic ceramic chip. They will last forever, and love a dV/dT environment. There are trades though in capacity level. It's easy to get a 100uF Electrolytic, or a 1uF monolithic chip. You have to design a little differently to use low capacitor values.

Electrolytics belong in 5 year life consumer electronics. Automotive ECM's deserve better.

Final word, given your description of the failure mode, (two years of good service, then wham), you did nothing wrong. You got bit by an electrolytic capacitor wear out mode. In reliability modeling, its called the "bathtub curve." Electronic components have a high infant mortality, and a high failure at end of life. In between they last forever! That's why we precondition space flight hardware. It's called "burn in" we cull out the infant failures, then fly the stuff for typically 1/3 to 1/2 of the known good life.

Hope this helps.

 

Thankyou!

Im just glad to hear that theres a good chance it just wore out.. and its not anything to do with my wiring harness etc..

Afterall the only thing i had apart was the tailight harness and i doubt thats connected to the ECU directly.

Thanks again!

 

I would like to see better close up pics, there is a wiring related issue with Q31 on that side of the board.

http://nondata.com/smoked_p28/smoked_p28.html

-PHiZ