Engine shut off but did not lose power

mazda
protege

#1

My sisters 2001 automatic Mazda Protege (1.6L) was driving on the interstate last month when the engine shut off but didn’t lose power. The battery light didn’t come on prior but she didn’t remember if it did after tho. The starter clicked but like when the battery is low. The battery was dead or very depleted. (As in it was still had enough juice to power everything the next couple days we worked on it) we still recharged the battery after we got it running. We cleaned and ended up replacing the terminals and it worked after that. But that was a month ago and the same thing happened. She was driving it going 35mph when the engine turned off. The power was still on, head lights radio, dash light, she turned the key off and waited a couple minutes and tried to start it. But wouldn’t turn. The starter click(like the battery was dead, but the battery isn’t dead) we managed to push it while number to number with our van 1/2 mile or less in to a parking lot. The head lights were still bright the whole time, we tried to start it again but it wouldnt turn. I did check the codes. One was for the MAP (it’s been since she got it 3 months ago) but she has a new one (P0123) for the TPS. It does have a rough idle is is least rough but still rough on R D 1 2 and 3. But it seams like it drives best in 2 in town


#2

If you have good jumper cables connect one from the negative terminal of the battery to a good metal ground on the engine. If that lets it start replace your ground cable from the battert and maybe one from the body to engine.


#3

It doesn’t take nearly the amps to run the headlights that it does to run the starter.
Get the battery tested, if only to rule it out. But a dead battery wouldn’t explain stalling in traffic; in theory you can run without a battery AT ALL, so long as you have a good alternator, though it’s certainly not good for the electronics.

So, second item, load test the alternator. You didn’t perchance, check the battery volts with a multimeter when the car died, did you? That data would be interesting.

If it’s not the not the alternator, either, then something CRITICAL must be failing while driving that would kill the engine. Not the TPS or MAP you mentioned, though: you’d still operate in “open loop” mode without 'em.


#4

Be sure to fix whatever’s causing the electrical problems first, as that might well make the other codes go away. MAP sensors are not a common failure item. And expensive to replace, especially if they are actually good. Battery/charging system test is needed. Also, try driving the car with just a single key in the ignition switch, see if that has any effect. Sometimes keys dangling will damge the ignition switch and cause weird electrical problems like this.

As mentioned above, you can’t judge the cranking ability of a marginally charged battery by its ability to light the dashboard and headlights ok.