I was on the highway in a major traffic jam (someone five miles down flipped a garbage truck, Miami sucks!) when suddenly, the radio died. Not long after, my temperature gauge dropped drastically followed by my tachometer going to 0 rpm- despite the engine being on. Shortly after, the engine started chugging and it died. My brother came to rescue me and we were able to push start it and it drove for all of 500 ft before dying again. From there, we towed it off the highway and then called a tow truck. So far, I noticed that the nut fell off the bolt that holds on the alternator, allowing the bolt to shift forward. However, the tensioner was still in place and the belt was still tight. I will be diagnosing and fixing the car on Saturday. Just thought it would be humorous to hear what you gentlemen think is wrong with it. May the ball busting begin!

 

the lower nut? then that's what "killed" your car.

 

That's exactly what happens when your car isn't making enough voltage to run the electronics. The nut falls off the alternator, the car runs on battery voltage til it drains, then electronics start to die off one by one until finally your ecu isn't getting enough power to run and the car dies.

Put the nut back on, re-charge (or even jump) the battery and it should be good as new.

 

I had the same symptoms when my alternator crapped out here recently.

 

I believe he's talking about the pivot bolt, not the one that holes the power line on. In which case, if the belt is still tight, it is curious. If the pivot bolt fell out enough to let it slide off the block, that's one thing, but it doesn't sound like it did.

You're definitely describing symptoms of a dying or missing alternator. Get it checked, install it correctly, charge your battery, and you should be fine.

 

Lots of MCM fans here looking at the 180 datsun alternator... I still can't believe that guy abandoned a car for 5 years at his brothers house and then sold it because it was "blown up"!

I thought the Miata had a pivot bolt that screws directly into the bracket from the rear rather than having a bolt and nut... was I mistaken?

Keith

 

the 90-93 has a nut, im almost positive.

I've had issues charging, if the lower pivot bolt wasn't good an tight, even if it still had good tension from the upper end.

 

If the alternator is dead, I've somehow accumulated a decent pile of working 1.8 NA alternators. You're welcome to have one if you want to drive the ~2hrs to pick it up.

 

Correct, I was referring to the pivot bolt. My apologies for the mixup, I should have been more clear.


Yes, my car is a 90 and had a nut. Glad to know that can cause charging issues. I'll try installing a new nut and lock washer.

Awesome, will definitely contact you if it is dead. Thanks!

 

Not good when u randomly lose your nuts.

 

A quick check with a voltmeter revealed that the alternator wasn't charging. I took it to Autozone where they checked it again and confirmed my findings. Fortunately, it was still under warranty and I should have a new one today. I was busy with work, so I didn't get to around taking it out until yesterday.

 

I installed the new alternator yesterday and push started the car. It's running good as new, it would seem that the previous alternator they sold me was just rebuilt badly. However, my tachometer has now stopped working. It goes from below zero to zero when I turn the car on, but it doesn't go past there. The repairs never end with this car rofl.

 

There were all sorts of strange electrical symptoms going on when my alternator wasn't talking to the new Haltech ECU, resulting in the battery going flat. Maybe try disconnecting the battery, then give it a full recharge, then see if all the electrics go back to normal?

 

what year miata do you actually ******* have?

 

ROFL, my Miata is a 1990. See post number 9 in this thread.

 

Bad ignitor.

 

It turns out that the ignitor wasn't bad. The gauge was just stuck for whatever reason. I sped up when merging into traffic one day and the tachometer just started working again.