Car randomly cuts off on it's own.

**ragedsparrow** · 09-20-2012

Greetings,

My car has been cutting off randomly the past couple of months. I have 81k miles on it. I change the oil every 3k miles and keep all the fluids in check. I use 93 octane gas (I initially thought that was the issue at first...forgive my lack of knowledge of cars, I'm learning). The car is a 2007 Grand Prix GT, 3.8 Supercharged. It's not getting hot, the temp gauge is usually only just above the 1/4 mark. It's not throwing codes. I bought a reader and it didn't throw anything even after it just randomly cut off. I've taken it to the dealership and after 4 hours, they told me that they couldn't find anything. It's not losing power when it cuts off, all lights on the dash, AC, radio, stay on when it cuts off. Most of the time the engine will start right back up after cutting off, occasionally I have to let it sit for a few minutes before it will start. It turns over just fine after cutting over and like I said before, most of the time it starts right back up. Every time I start it I turn the key on, wait about 4 seconds and start the engine. There isn't really any consistent condition it cuts off in either, it's done it when I'm on the gas, it's done it sitting at a stop light, it's done it when I'm just coasting. I'm at a loss and was wondering if anyone has any input or suggestions.

Thanks!

**machinegunsquid** · 09-20-2012

Possibly a very upset CPS (Crank position sensor) Though it will usually throw a code for that.

**Fivefingerdeathpunch** · 09-20-2012

Shotgun a crank sensor in it.

9/10 it will never throw a code for random stalling like you are seeing.

**ragedsparrow** · 09-20-2012

The Check Engine light is also not lit. I don't know if that helps any, but I wanted to add that information as well.

**Fivefingerdeathpunch** · 09-20-2012

Right, the check engine light will normally never go off.

The crank sensor just fails and when it does, stops the signal and then the PCM thinks the car is shut off and stops spark and the car dies. But then you shut it off and restart it and sensor works again untill it fails again.

I'd buy a new one and install it, there is a write up in the how to section that shows you what tools you need and how to change it.

**ragedsparrow** · 09-20-2012

I'll try that then. Thank you for the information, I appreciate it.

**machinegunsquid** · 09-20-2012

Here's the thread FFDP mentioned.

http://www.grandprixforums.net/crank...ent-2-698.html
The actual write-up on the first page is a broken link, but if you scroll down you'll see pictures and directions.

And ffdp, I didn't even think about the sensor outright failing.

**00grandprixgtp** · 09-20-2012

Lol seen that before also seen a Maf sen messed up do that never set s ses light lol least mine didn't when the maf went out if I moved the Maf sen wires the car would stall out