Intermittently engine shuts off during normal driving

PISSED OFF TRAVI

MEMBER
1991 PONTIAC BONNEVILLE
245,000 MILES

Driving along just and engine just shuts off. It might start right back up and wont do it again for 75 miles and it might do it 10 times in the next 5 miles or it may take 30 minutes before it starts again does it more in the heat of the day less when weather or engine is cooler reading code 4. Changed ignition module changed, the cam position sensor, changed the coil pack, spark plugs, wires, wiring harness to the ignition module and even harmonic balancer all trying to fix this issue. Any ideas?
engine runs good just this shutting off issue

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,644 POSTS

Hi,

The code you listed doesn't exist in the OBD1 system. They start at 12. Are you sure that is what was found? Take a look through this link that explains how to retrieve codes from an OBD1 system and let me know if you still get the same code:

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Now, what you described sounds like a bad crankshaft position sensor. You mentioned several things that were replaced. Was the crank sensor replaced?

Take a look through this link and let me know if it mirrors what you are experiencing:

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

When the sensor starts going bad, it will often fail due to heat. After cooling off, it will work again. When it fails, spark is lost to the plugs. So, you could check for spark when it doesn't restart. Here is a link that shows how that is done:

https://www.2carpros.com/articles/how-to-test-an-ignition-system

IF you determine it is bad, here is a link that shows in general how to replace one:

https://www.2carpros.com/articles/crankshaft-angle-sensor-replacement

The attached pics below are the directions/pic specific to your vehicle for replacement.

Let me know if this helps or if you have other questions.

Take care,

Joe

See pics below.

Images (Click to make bigger)