1997 Mitsubishi Eclipse Car Shuts off while driving.

JAMALRW

MEMBER
1997 MITSUBISHI ECLIPSE
4 CYL
2WD
AUTOMATIC
170,000 MILES

I own 1997 mitsubishi eclipse, 2.0 DOHC non turbo automatic, 170000miles.

Im trying to figure out why my car just shuts off in the middle of driving it.

The car would start with no problem at all, and as long as I leave the car in P park It will run forever with no problems at all, But as soon as I shift to D drive and drive the car for about 30 seconds It shuts off instantly as if I turned the key to the off pisition.

I did the alternator check when u remove the positive battery post while the car is running, and sometimes it shut off but not all the time. A new alternator has been put on the car but still the same problem, so I got a new battery too, and as im driving it with the new battery, car shuts off after a long time now, but before it shuts off the check engine light comes on and the battery light comes on.

do any of u know whatthe problem can be?

1 Reply

CARADIODOC

MECHANIC
33,743 POSTS

Hi jamalrw. Welcome to the forum. One of the worst things you can do is run the engine with the battery disconnected. That was a poor man's trick done many years ago by mechanics who didn't understand how to test electrical systems. Generators put out a pulsing DC voltage that varies from around 11.0 volts to 16.0 volts. The battery smoothes out those pulses and stabilizes system voltage to 13.75 to 14.75 volts. Without the battery, two things happen. The voltage regulator responds to the dips in output voltage by boosting the charge rate of the generator, so voltage goes even higher, and that higher voltage that is used to power the generator creates a bigger electromagnet which causes output voltage to go even higher. If you increase engine speed, it is real easy for the generator to put out 35 volts or more on a test bench. It won't get that high on the car because it will destroy all of the computers and it will stop running. You can easily do a few thousand dollars worth of damage by just pulling a battery cable off while the engine is running. And that's if the generator is working properly. If there is one defective diode in its output circuit, the pulse of voltage will be exaggerated and the regulator will go nuts trying to increase system voltage. Voltage spikes will also be present which can kill computer modules. At the very least, some of the computers will do strange things due to the unstable voltage powering them and from the erratic voltage signals coming in from the various sensors.

The proper test is to measure battery voltage with an inexpensive digital voltmeter. Fully charged, it should measure 12.6 volts. While the engine is running, it must be between 13.75 and 14.75 volts.

Since the Check Engine light came on, there is at least one diagnostic fault code memorized in the Engine Computer. Many auto parts stores will read those codes for you. That is the starting point in diagnosing the stalling problem. The crankshaft position sensor and camshaft position sensor are likely suspects, especially if the engine will restart after cooling down for a half hour or so. Those sensors often fail by becoming heat-sensitive. A related fault code will be set in the Engine Computer.

Caradiodoc