Resolved 2g Break up at cruise, loss of ECU ignition signal

[97gsxIA]

Hey guys, brought the car out of winter hibernation and the first drive was rough.

Ignition kept cutting out over 3k, and had a hard time keeping up idle. Pretty normal troubleshooting has been done, but I'm posting this now because I noticed something odd:

In ecmlink both the rpm and speed value drop momentarily to 0 in milliseconds during these breakups, making me thing it's a wiring issue.
Perhaps a bad connection on the white wire from ECU to PT? That controls both these signals right?

The wiring is underneath my sheet metal intake so, I'm just gathering my thoughts before I descend into the shit.

Lemme know if any of you have thoughts on it.

 

[steve]

The ECU doesn't use the white wire from the PTU for either of these.
The RPM's come from the crank sensor (or cam angle, I forget which) and the speed from the VSS.

 

[97gsxIA]

Looked back at my log and it looks like it's not just my rpm and speedo, but just about everything shuts off for these brief moments, coolant temp spikes to what i assume is max reading, voltage drops from 14 to 12, ecu seems to lose chunks of .3sec of time.

Is it cutting power for brief moments?

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[steve]

Too early in the morning to think it through, both ECU and wiring are likely suspects. Lets see the ECU board.

 

[97gsxIA]

So I popped the ECU out and I think I identified some damage. Can anyone confirm what this driver chip is? It appears to have popped and spread some juices down and across the board.

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[steve]

I can't tell if it's damaged or just has cracked conformal coating which is normal.

 

[97gsxIA]

Yeah it's tough to get pictures. There's a tiny brown spot on the cracked surface and it is raised like a pimple. The opposite metal bracket had that spider webby looking corrosion right in front of this spot. And there's a track of fluid from this spot all the way to the corner.

You know what this driver chip controls by chance so I can confirm/exclude my ecu symptoms?

Attached is a couple more pics

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[97gsxIA]

Yeah, I'm not so convinced this is damage, like you said. I scraped a bit of that cracked portion and it looks like a gooey coating of sorts. Flipped the board over and didn't see any damage on the leads.

Kinda stumped.

 

[97gsxIA]

So a thought here:
If the coolant temp sensor, front o2 sensor, tps voltage, baro, iat, vss, ign. timing(cps) all peg to max/min/default values I would assume to check their grounds and see if they share them. I see a majority share pin 92 on the ecu for ground, and a few others are a chassis ground on the ground behind the foot splitter air duct.
The track for pin 92 doesn't seem damaged on the ecu, leaving the chassis grounds.

Are there any others or anything else I can check?

 

[97gsxIA]

Forgot to come back and update.

This is going to sound crazy but it ended up being my power windows circuit grounding by the fusebox to the tranny.
I realized my windows didn't work, and found the harness worn through and the power windows wire, and one other red wire ripped open and grounding to the tranny. I'm thinking the other wire was a wire that provided power to the ecu.

So crazy/lucky find. If the windows had worked it would have taken forever to find the short.