nightwulf
08-25-2006, 08:31 PM
Hello, folks. I've recently had a 97 Grand Am GT (3.1 V6) given to me by a friend. The car is in decent shape, can't beat the price, and it gets me to work and back. Usually ...
Background: the "Check Engine" light is always on. The code returned is always 0420 (catalyst efficiency below threshold). On occasion, roughly once a month, the "Check Engine" light will begin flashing. So far, when this occurs, the additional code returned is always 0304 (cylinder four misfire).
While the light is flashing, the car runs horribly. The engine seems to shake while idling and during acceleration, up to ~30mph. Acceleration is also much slower than normal. Fuel economy is also greatly decreased. I live roughly 15 miles from work. If I have to drive the entire 15 miles with the light flashing, I'll easily go through an eighth of a tank of gas. After a period of time, generally about a day, the engine will smooth out and the light will return to solid.
This only happens just after the car is started (I can tell within about two seconds of hearing the engine; long before the light starts flashing). It does not suddenly start happening while on the road. I've also noticed that when this happens, the vehicle seems to crank weaker than normal. On one occasion I released the key from the "start" position more quickly than I normally do, and the light started flashing. Turning off the car and restarting it several seconds later, making sure to let the engine fully start before releasing the key, corrected the problem.
Once the problem stops and the engine light stops flashing, I'll check and clear the codes. So far, it's always been 0304 and 0420 that are cleared. After driving about five miles, the engine light will turn on again (solid, not flashing), and checking the codes at this point will only yield 0420.
The car has roughly 134,000 miles on it, so I'm not looking to spend a ton of money into fixing it. This car is intended to get me to work and back while I save money to purchase something better. So far I've had the spark plug and wire replaced (on cylinder 4 only) and it's made no difference.
Another problem which probably isn't related is the AC. The car makes a high-pitched grinding sound while running, and there are small metal shavings scattered near the AC compressor. I've had a few different people look at this specifically, and all believe the problem is the compressor. The AC doesn't work either (blows, but blows hot). I'm not interested in fixing this due to the cost (and I can live without AC), but if it's somehow related to the misfire problem, I may not have an option. Could metal shavings from the compressor somehow find their way into the engine?
While I'm far from a "gearhead," I do work in an auto service center (as a service writer), so I have a staff of technicians to assist with my problems. One (the same one who replaced the plug/wire) suggested to also replace the coil pack, but offered that anything further than that is probably more money than I want to invest in this car.
Does anyone have any suggestions as to the cause of the problem, or ideas of (relatively) inexpensive items to replace which could help? Thanks much in advance.
Background: the "Check Engine" light is always on. The code returned is always 0420 (catalyst efficiency below threshold). On occasion, roughly once a month, the "Check Engine" light will begin flashing. So far, when this occurs, the additional code returned is always 0304 (cylinder four misfire).
While the light is flashing, the car runs horribly. The engine seems to shake while idling and during acceleration, up to ~30mph. Acceleration is also much slower than normal. Fuel economy is also greatly decreased. I live roughly 15 miles from work. If I have to drive the entire 15 miles with the light flashing, I'll easily go through an eighth of a tank of gas. After a period of time, generally about a day, the engine will smooth out and the light will return to solid.
This only happens just after the car is started (I can tell within about two seconds of hearing the engine; long before the light starts flashing). It does not suddenly start happening while on the road. I've also noticed that when this happens, the vehicle seems to crank weaker than normal. On one occasion I released the key from the "start" position more quickly than I normally do, and the light started flashing. Turning off the car and restarting it several seconds later, making sure to let the engine fully start before releasing the key, corrected the problem.
Once the problem stops and the engine light stops flashing, I'll check and clear the codes. So far, it's always been 0304 and 0420 that are cleared. After driving about five miles, the engine light will turn on again (solid, not flashing), and checking the codes at this point will only yield 0420.
The car has roughly 134,000 miles on it, so I'm not looking to spend a ton of money into fixing it. This car is intended to get me to work and back while I save money to purchase something better. So far I've had the spark plug and wire replaced (on cylinder 4 only) and it's made no difference.
Another problem which probably isn't related is the AC. The car makes a high-pitched grinding sound while running, and there are small metal shavings scattered near the AC compressor. I've had a few different people look at this specifically, and all believe the problem is the compressor. The AC doesn't work either (blows, but blows hot). I'm not interested in fixing this due to the cost (and I can live without AC), but if it's somehow related to the misfire problem, I may not have an option. Could metal shavings from the compressor somehow find their way into the engine?
While I'm far from a "gearhead," I do work in an auto service center (as a service writer), so I have a staff of technicians to assist with my problems. One (the same one who replaced the plug/wire) suggested to also replace the coil pack, but offered that anything further than that is probably more money than I want to invest in this car.
Does anyone have any suggestions as to the cause of the problem, or ideas of (relatively) inexpensive items to replace which could help? Thanks much in advance.