I bought my 88 n/a used from a guy I've know for 18 years. Sometimes, especially when it's raining, when I get in the car and start it after about two seconds this really annoying beep comes on (the same beep at the rev limiter only it's continuous) and won't shut off for about five minutes. I asked the previous owner about it and he said it had something to do with water in the cpu or something like that. Has anyone had this problem before?

Also my car has a nasy habit of draining my battery. Could this contribute to that drain?

Last question is what would be the best battery to get to replace my old one. My car wouldnt start yesterday and the battery wouldn't hold a charge so I need a new one.

Thanks

 

it's not your low coolant buzzer, is it? Do your idiot lights work?

And it sounds like it's time to check your charging system. Make sure the alternator is putting out the appropriate voltage, something like >13.5v. If all that's working, then look fo a short to ground.

 

The buzzer is tripped by low water level or low oil level or over revving the engine.
There are warning lights for low oil or water.
The lights should all come on as a self test when you first turn on the ignition.

Since your alarm seems to be rain/time related, and the oil & water lights test OK, you need to look for wiring connector problems.

The two common causes are corroded connector pins and cracked solder joints where the connectors meet the circuit board eyelets.
Start with the connection on the back of the warning light/clock panel.

 

The previous owner of the car said that it could be one of two things. The first was the seal around the radiator cap, which I'm going to check when I get home, and the second is a $1200 replacement of the main cpu. Also what's the best way to test an alternator. I don't really have many tools at this point so should I just go get it done at a shop?

Still need advice on a good battery brand.

 

SureShot, I have been looking for service manuals online for a while and I just found your links. Awesome.

 

It's got nothing to do with the CPU so don't worry about it.

The warning buzzer is for either low oil or low coolant, and will be accompanied by one of the warning lights. Check both oil level and coolant level (in the radiator).

If they're both full, check the warning systems. Go to www.iluvmyrx7.com and download the Factory Service Manual (FSM) in PDF format for free. You need Part 1 of the Body Electrical chapter for this. Instruction for checking both systems are in there.

If you suspect the radiator cap, just replace it with a new one from Mazda. It's a cheap and easy way to eliminate one possible cause of low coolant.

Take your car to a battery shop and have them check it.

 

The battery:
The rotary engine needs less power to crank then other engines.
It just has to spin fast enough to gain some compression.
(I once cranked mine with a cordless drill)
Any battery on sale that fits in the box will do.
Be careful of the +/- polarity, or you will be buying a new ECU.

FYI:
CPU - A small module by the driver's left foot, handles horn, secutity alarm, seat belt alarm, turn signals, key in beeper, lights on beeper.
ECU - A larger module under the carpet in front of the passenger's feet, controls the engine fuel, spark, & emmissions controls.
Warning buzzer - is part of the dash gauge cluster.

Check out the manuals link in my sig below - body electrical section.