Car is Trying to Freak Me Out

[Superman]

Last night when I got home, my idle was fluctuating a bit (it does this now, but did not do it before the rebuild/new cams). Just before I shut it off, the idle surge got a little stronger pulsing about once per second and the OXS and ALT lights flashed. They flashed on when the idle increased, and went off when the idle fell. They did this continuously, until I shut the car off.

Does this car have a poltergeist?

[john70t]

Is something shorting out like an under the dash harness or the aux air valve?
Mabye the voltage regulator quit(~13.5v in the alternator, ~5v from computer to the sensors) and it's super-overcharging and knocking out electrics on the way.

[Superman]

I don't think there's a short or voltage regulator problem, but perhaps. The ALT and OXS lights cycling on and off was very rhythmic, synchronized with the engine's idle cycling. Twenty-five years ago I would probably have dismissed it as a hallucination, but I haven't used those drugs in many years now.

Recently I noticed my headlights were subtly changing brightness, so I measured battery voltage recently after shutting the engine off. 13.4 volts like it should be. If it had been 15 volts or something, I'd worry. Perhaps I'll chech system voltage while it's running, but I don't believe the VR is bad.

As far as shorts are concerned, obviously they can happen. My car happens to be a relatively unmolested example of the '83 SC, so I have some confidence in the wiring harness and connections.

[rstoll]

Are you running the oxy sensor?

[Superman]

No. And this is what I find interesting is that the device that turns the OXS on is not actually connected to the fuel or exhaust system at all. It is simply a mileage counter which I have disabled by unplugging the ground wire that goes to the tach. So, it should not have current in it.

[rstoll]

Unplug the relay under the seat while idling and see if the idle changes at all. If not replace the relay. Also check and make sure heater on wur is plugged in. Might check continuity on the heater also.

[Superman]

If it's the frequency valve relay, I've already got a new one...JW suggested I replace mine. I'll check it out.

By heater continuity I think you may mean the WUR heater or the AAR heater. True?

Thanks, Bob.

[rstoll]

Yeah, the WUR heater. Mine came unplugged the other day and it hunted and really richened up. Plugged it back in and it straightend out.

[john walker's workshop]

do the dome lights still work? that's where the relay gets it's power. overcharging would not rusult in a surging engine, but you would check voltage with it running, preferably when it's doing it's headlight thing.

[Superman]

Yes, the dome lights work. I'll check voltage with the engine running but I have some confidence that's not the problem.

When I changed headlights and went to the 100w high beams, I inspected the ground connection, perhaps even removed the fastener. But I think that headlight bucket ground is where the light fluctuation is coming from. I'll check it out.

And I'll install that new relay. Thanks, John.

[emcon5]

The only thing I can think is that those 2 lights come on when you first turn on the ignition, to show the bulbs work I guess.

Does your seatblet buzzer work, and if so, was it buzzing when this was going on?

Tom

[Superman]

I castrated the buzzer.