I have read at least twenty posts on this issue but most just end without posting what they found the issue to be.

I have an 03 Monte Carlo SS 3.8. It has around 135K on it. It has died on us twice now. Once backing up an incline and when driving around 35 mph down a street. It starts right back up if you put it in neutral but the steering and such does lock up til then. It died on my teenager who had no clue what to do.

When we bought it, it threw a CAT code, so we change the CAT out last week. I have noticed if you start it, then turn it off and let it sit a few minutes, then restart a smell of exhaust in the car or just around the outside (my door is usually open so may just be outside).

I did the tap test on the MAF last nite and it had not change in the engine. I plan to remove the MAF and see if it needs cleaning or if its bad. But I have a feeling it's something else. I am thinkin the engine dying with the fuel smell, may indicate a fuell injector or fuel pump issue but I am not sure yet. I have well paid my mechanic the past few months on other vehicles and I am one to try to figure things out before I take it in.

So MAF, fuel pump? I see some post its the crankshaft position sensor or the ignition module, but most post did not mention having the exhaust smell in addition to the engine dying.

Just wanting some thoughts and resolutions!
Thanks ya'll!!

 

Update: Took it back to mechanic. They couldn't find anything wrong with the new CAT. They cleaned the throttle body, MAF, and looked and tested the IAC. (no charge for all this) Picked it back up. The unsteady rpms on idle is better but it died on me again while sitting in a drive through. I put it in neutral and it starts right back up.


Any thoughts? My mechanic said since there's no codes pulling this could get ugly...

 

Did your mechanic check the fuel pressure regulator? Mine went bad and started leaking fuel directly into the intake manifold and it ran like crap and would die at idle in gear and was hard to start when warm.

 

No I haven't but I will tell him. The exhaust smell went away once he changed the CAT. It was just a day or two and that stopped. The CAT that was on it before was completely gutted.


The check engine light is back on for P0420 so I think maybe the down O2 sensor is bad, and the dying I'm leaning towards the crankshaft position sensor. I will see if he can check the regulator as well.


I also have water in the back passenger floor board. I think I have a seal on the back side window (2 door) that is bad though so I'm gonna reseal that and see if it works.


Thanks for the suggestion coolhand!

 

If your window seal turns out to be ok, check up under the glove box against the firewall for any moisture because you could also have a leaking heater core.

 

Update: Had another incident of the car dying while driving. Did it ALOT this time. Got it to the mechanics, and he let it run for 3 hours before the pressure started dropping. He replaced the fuel pump, filter and relay. We will see if this solves the random dying issue. Still not sure about the check engine light and haven't had a chance to check the firewall for leaks yet but luckily no rain here in a while!

 

Just got the car back. Stopped put gas in, the died on me while idling five minutes later. So guess the pump wasn't the only problem. Help would be greatly appreciated!! We've now spent $800 and not fix it.

 

If I missed the update I apologize for that. But I am wondering about .
1. Fuel Filter
2. Air Filter
3. Injector Cleaner
4. Vacuum Leak (this is what it sounds like to me).

5. Also check to see if you have a Cabin filter that could be plugged and causing the smell inside the car.
6. I thought I had an Exhaust leak on my 06 Pontiac and they found the weather strip was off and fixed it and put in a new cabin filter.

Hope you find the issue.

 

I had a similar problem with my 2002. it ended up being the MAP sensor. The old one actually started to melt apart. Put new one in and problem fixed.

 

The exhaust smell only happens now when it dies and I rev it up to get it going again.

He changed the Fuel filter, Fuel Pump, Fuel Relay switch. He just put a Crank Sensor on it and it died again after hours of running. Computer isn't showing anything at all when this happens.