1999 Chevy Monte Carlo Wont run longer than 10 min

NGRUNDL

MEMBER
1999 CHEVROLET MONTE CARLO
6 CYL
FWD
AUTOMATIC
127,000 MILES

My car will not run for longer than 10 min or so. If you try to restart it after it dies the exhaust is rich and it will not hold an idle. If you let it cool down it does the same thing again. I recently replaced my plugs and wires and coil packs. What else could it be? I've been told several things. One it could be my temperature sensor? Two it could be my cam shaft sensor? Without a engine light on I can not diagnois it. Please help it is starting to get cold out.

1 Reply

RENAUDTN

MECHANIC
636 POSTS

Your coolant sensor is a good possibility:
10 minutes is probably what it takes for your engine to reach normal operating temperature; at this point your car should switch to closed loop mode. If your coolant sensor is defective, it won't go into closed loop resulting in your ratio fuel/air being too rich which flood your engine (which could explain the black exhaust when you restart the car). A way to check that, is being removing a spark plug when it happens and check if it's soaked in fuel.

Now it could be something else too; beside checking your coolant sensor and your spark plugs, do a fuel pressure test as well.