Gm HEI upgrade on a 78 280Z

[Zed Head]

Does the needle vibrate or twitch at all?  Did you disconnect the original module by the fuse box?

My tach wouldn't work right until I added a condenser on the negative side of the coil.  It would just sit there and twitch and jump.

[TomoHawk]

My condensor is on the + side of the coil.  Should I add another, or switch it?

Where do you get condensors?  the only on I've seem lately was at the  lawn mower section at the DIY store.

Edited June 7, 2018 by TomoHawk

[Zed Head]

I added another.  But you want to make sure that the tach is actually connected first, of course.  You didn't answer the other questions.  The tach needle would probably do something if it is connected.

Many people don't have any problems at all.

[TomoHawk]

Yes, the first thing I did was to unbolt and unplug the old ignition box.  It's sitting here on my desk.   Then I traced the blue wire from the - side of the coil to pin #1 on the ECU, as well as checking the other important things (grounds and power) according to the 280Z EFI handbook.  Then I connected the HEI module.

So right now, the tach needle isn't moving at all.  Before, it would twitch a small bit while cranking.   I thought there was a second (black) wire on the - side of the coil, but I don't see it now. 

Edited June 7, 2018 by TomoHawk

[TomoHawk]

I can't explain it, but the rev counter started working after I taped up the unused  connectors.

The thing only needs some adjustments and a tune.

Edited June 16, 2018 by TomoHawk

[Captain Obvious]

All that means is that it'll come back again some time in the future. 

[TomoHawk]

I don't really understand what you mean by  'it'll come back again some time in the future,'  Bruce.

I think it was a good thing to replace the factory ignition module.  The engine seems to run more smoothly, and I've gone about 45 miles in the suburbs with the gas gauge needle moving only slightly, when, for the same driving with the old setup, I would've used about 1/8 tank.

I'll have more  data after next weekend, when I will be going about 400 miles.

I'm also still interested in adding a remote relay or a kill switch to the 12V feed coil.  It's probably better than putting a SPST switch on the distributor sensor wires-  I think that's what killed the old ignition module, even though it was missing some anyway. You could easily disguise a SPST switch as a gauge lighting dimmer knob...

Edited June 16, 2018 by TomoHawk

[Captain Obvious]

I was (half) joking about it coming back again in the future. It's an old engineering adage taught to me by one of my mentors that if you have not positively confirmed the root cause of the failure, then it's likely to come back again.  

Here's to hoping that's not the case here!

[black gold man]

I think what kills the ignition and even cause of hot restart problem is under hood temperature caused by ex manifold leak. You can have a bad gasket leak and not be loud.

 

[Zed Head]

The ignition module was in the cabin until 1979, when they introduced the ZX "match box" distributor module.

We have pummeled the hot start topic in previous threads.  Definitely heat-related, but seems to be general heat around the injectors.  Happens without exhaust leaks..

[TomoHawk]

Mine looks like some water got in the box as well.  I should test the power transistor to see if it's still good-  I suspect it's degraded or just dead.  If that's the case, I'd say the wiper amp suffers from the same problem, which wold explain the slow wipers.  Then I'd take a look inside to see if you could build a better one with modern parts.

BTW-  where can you get a NEW wiper amp unit?

 

Edited June 22, 2018 by TomoHawk

[Captain Obvious]

That doesn't look like it got wet to me. Just looks like old non-sealed electronics IMHO. And if it's dead, I wouldn't bother trying to troubleshoot. They're easy enough to find used still working, and failing that, there are aftermarket options.

How's this for a litmus test... Even I wouldn't spend a lot of time trying to fix one of those.  

And the reason your wipers work slow is probably a completely mechanical issue. Crud and rust in the linkage, especially where the wiper stalks poke out of the cowl area up to the glass.