Sat for two days, now won't start/run.

[Zed Head]

I can't find a good thread about reflowing the solder joints, even though I said there were threads on the forum about it.

If you have a good eye and/or a magnifying glass you might be bale to see the cracked joints.  Apparently they are on the line of 35 pins where the connector connects.

This thread has a lot of good info and pictures, in general.

The line of solder spots on the right - 

[NocturnalEmber]

2 hours ago, Zed Head said:

I can't find a good thread about reflowing the solder joints, even though I said there were threads on the forum about it.

If you have a good eye and/or a magnifying glass you might be bale to see the cracked joints.  Apparently they are on the line of 35 pins where the connector connects.

This thread has a lot of good info and pictures, in general.

The line of solder spots on the right - 

 

I plan on holding onto my old ECU, so I'll likely see about getting the cover off and looking into those joints. I've had to redo some cold solder joints in some of the electronics on another car so I've got some experience in re flowing/redoing them. Ideally with a known good ecu I'll be able to finally have it consistently running right.

[NocturnalEmber]

4 hours ago, SteveJ said:

Yep, it's the ECU. When you have to resort to percussive maintenance, it's pretty much ready for a restoration.

I'm hoping that's the definitive cause of all of this. No idea how it could go from running to not running when absolutely nothing was touched on it. Should hopefully be able to borrow an ECU to test and verify.

 

2 hours ago, cgsheen1 said:

When you pulled the connector off the ECU did you check the contacts on both the plug and the ECU?

We've seen water damage (corrosion, oxidation) on the ECU connector from cracked and/or leaking windshield gaskets. 

I didn't notice anything on the ECU pins or the harness side connector myself.

[NocturnalEmber]

Random thought - Hopefully someone can chime in.

 

I do seem to be missing the bolts that hold the ECU to the bracket.  Does anyone know what spec these are so I can source some replacement hardware? Searching hasn't turned up any definitive answers, and being that I don't have any, I can't replicate based on that.

[Zed Head]

Any screw in the vicinity will probably be a match, they're not special.  Look around under the dash and try a few.

[Yarb]

@NocturnalEmber So the ECU has not been tied down since you purchased the vehicle? Pretty big clue someone has tampered in this area previously. With that being said at this point we’re not sure this possibly isn’t the original.

[NocturnalEmber]

@Yarb, I got a pretty good look under there before/after I replaced the engine harness and I couldn't see anything amiss connection wise.

 

While I can't say for certain, the way the retaining screw and ECU plug on the old harness had attached themselves together, I'd be willing to bet that it's original.

Plus the general condition of other components that I've replaced, it doesn't seem like much of the car was touched, seems like it sat untouched for quite awhile if I had to guess.

[Yarb]

Maybe I missed something. I thought the ECU itself was not mounted to the body.

[NocturnalEmber]

@Yarb you're right, it wasn't physically bolted to the body.  I have no way of knowing that it wasn't removed, but based on everything else around the car I feel comfortable saying it's original.

 

ex: Fuses being oxidized to the point they had so much resistance that interior electronics wouldn't work.

Brake and clutch master fluid had turned to powder, anything in the car was dating back decades, etc.

 

Of course this doesn't guarantee anything, but it correlates with the story that the car sat in a garage for quite awhile, so I'd be inclined to believe it's an original ECU.

 

 

[Yarb]

Just strange why it was removed, hardware missing. At this point no one will ever know. 

[Zed Head]

#12

https://www.carpartsmanual.com/datsun/Z-1969-1978/engine-280z/e-f-i/control

 

[NocturnalEmber]

@Zed Head I had that website saved and lost it when I installed a new nvme drive in my PC, thanks for that!  I kept googling trying to find it and I was using just the wrong amount of keywords to not get a positive hit. 

 

@Yarb Strange indeed, I think they were looking for anything obvious and just didn't go past a visual inspection, because of the lack of tampering I've found anywhere. I really wish I had taken more pictures. How long does a car have to sit for the brake fluid to turn to powder anyway? I've never seen that before, though being that basic things weren't even touched, like fuses, I think it was largely left alone.  If only I had a crystal ball.