Electrical Gremlins.

[Nightpath]

So I've been patiently awaiting my  swap and I've been ironing out bugs.

Some of my last are the most mysterious.

At random times the car runs like crap. I'll get out, work for a bit then go home as if it ran fine all the time.

The headlight switch whines when it's off. I've replaced it and it still whines.

The tach is a crap shoot. When the car runs fine so does it. When it acts like an the tach does too. When running bad of I use the signals it will jump up 500 rpms then back, or will start working with the brakes pressed.

And the radio randomly resets back to factory when the car is turned off. If I power it up it usually has the saved setting but when I start it the radio resets.

It does a few other odd things, like the wipers randomly stop (new switch, have yet to install the new motor).

But yeah, it's a random problem. I just went 2 weeks without a issue.

[carnuck]

Sounds like a loose battery cable.

[Nightpath]

There is that possibility, but I don't think it is. I was thinking a bad ground possibly.

I DO have spare cables I might swap in to see if it makes a difference.

It is odd that the tach will work fine, then bump to nothing and only show RPM's when the signal light or whatnot is turned on.

Hmmm....

[Mernsy]

Check, and re-tighten the ground point on the firewall between the brake booster and the engine. It also doesn't hurt to run extra grounds between the engine and inner fender, engine and firewall, inner fender and firewall, etc...

[carnuck]

I was thinking ground cable to the body and forgot that word when I replied.

[Nightpath]

I'll check those grounds, might not be there at all. But I might get slack AND lazy since the new motor is going in in a few weeks, so I can add all sorts of grounds when I do that

[Nightpath]

I don't see a bonding cable between the brake booster and engine. Any pictures of where is at so I can add one?

[Mernsy]

Look for small black wires screwed to the firewall between the brake booster and the engine. It's a place where wires are grounded to the firewall. Not sure what a bonding cable is??

[Nightpath]

It would be the same thing. Those braided cables in the engine bay are bonding cables. Anything that grounds is a bonding cable. Just a different name for them.

Any pics of the screws? I see no wires at all

[Mernsy]

You can see my SX/4 has only one wire. My sedan has three, I think.
You can see a bit of the brake booster in the lower right hand corner.

(I hope the mods can archive this pic as it seems to be a very hard to find ground point.)

[Nightpath]

All the grounding points in the engine are there, and cleaned.

Issue still happening though. I can turn the key off and on, the radio has settings saved. Soon as I crank the engine it resets.

[Mernsy]

Where does the radio get its power from? Trace it back and change it.

[Nightpath]

I have the power source hooked right into the fuse box (fused of course)

[Mernsy]

You should have two power wires. One for the radio itself and one for the memory. Are they both hooked up at the same place?

[Nightpath]

That's the thing. The radio memory will randomly save. It's absolutely random.

The main power wire (which on my radio) is threaded right to the fuse box with the proper fuse in line. IIRC that wire is also used for the memory.