I'm much confused. Voyagers never came with V-8 engines. Which size engine do you have? Black smoke is a sign of too much fuel entering the engine. That is rarely caused by an injector. It would have to be stuck open which is very uncommon. Plus, Chrysler has very little injector trouble compared to other manufacturers.
When the Check Engine light turned on, that indicated the Engine Computer detected a problem and set a diagnostic fault code into its memory. The mechanics will connect a hand-held computer called a scanner to read those codes. Each code indicates the circuit or system with the problem, not necessarily the specific part.
The only o-rings I can think of that you're referring to are on the injectors. One is between the injector and the fuel rail. Leakage here would be a severe fire hazard, and you would easily smell the raw gas. These did have a tendency to shrink in very cold weather and leak on Intrepids, but never, to my knowledge, on the minivans.
The other o-ring is between the injector and the intake manifod it's plugged into. These also rarely leak unless someone had them out and didn't install it properly or cut one during the installation. Even that isn't easy to do. If this o-ring was leaking, extra air would enter the engine and would be detected by the oxygen sensor as a lean condition. The computer would respond by holding the injectors open for a longer pulse of fuel. No matter how much more fuel was delivered, the oxygen sensor would continue to see that extra air, and continue to report a lean condition. (Oxygen sensors only see unburned oxygen; they don't see unburned fuel). The result would be an engine that is idling too fast, black smoke from the tail pipe from the unburned extra fuel, and possibly a fault code indicating the exhaust gas is staying too lean for too long.
While the extra air would be entering near one cylinder, the computer doesn't know that, so it commands extra fuel for all of the cylinders. That one cylinder would be running lean, and the other five would be too rich.
You listed 35,000 miles. I can't imagine anything requiring engine replacement at twice that mileage. Is it possible instead of "o-rings" you're referring to "piston rings"? They would allow oil to be burned if they were worn, but that is highly unlikely. My 1988 Grand Caravan has 378,000 miles and doesn't burn oil yet. There is no manufacturer that has an oil burning problem with their cars from the last decade, especially at that low mileage. Oil smoke will be medium to light blue, not black.
Another possible cause of black smoke is a defective MAP sensor. He has the biggest say in how much fuel is delevered to the engine. His signal voltage must remain between.5 and 4.5 volts. Anything outside that range will be detected by the Engine Computer, a fault code will be set, and the Check Engine light will turn on. The fault code will lead the mechanic to the circuit with that sensor. A MAP sensor that is starting to fail can report an incorrect value which will result in the wrong amount of fuel going into the engine, but as long as that incorrect value is within acceptable limits, the computer will believe it and won't detect a problem. MAP sensors rarely take more than a few days to fail totally.
Have your mechanic connect a hand-held computer to read the diagnostic fault code(s). This should be done soon because if the problem doesn't occur again, the codes will erase automatically after starting the engine about 50 times, and that valuable diagnostic information will be lost.
If the only symptom is black smoke, I can't imagine anything that would require replacement of the engine. Without a more detailed explanation from the mechanic, that sounds like the wrong approach.
Sunday, February 28th, 2010 AT 5:19 AM