Every vehicle manufacturer issues a schedule of suggested (and sometimes required to maintain the warranty) maintenance. This list will tell you roughly every 5,000 miles what work you should have done to keep your vehicle in good working order. While it seems counter intuitive to fork over money to a mechanic when there appears to be nothing wrong with the car, it will work out to your advantage in the long run. Most vehicles today will last for 200,000 miles with few problems if that maintenance schedule is followed.
When routine maintenance is not done, all sorts of problems can crop up, bad water pumps and radiators from not having the coolant flushed, transmission failure from not flushing the fluid and engine trouble from not replacing spark plugs and having the carbon cleaned from the engine routinely.
Carbon is a naturally occuring byproduct in a combustion engine, it looks like a thin coat of black soot. Many things, like contaminants found in lower grade gasoline, a vehicle that is running rich, oil leaks, and short trip driving can lead to excessive carbon buildup and really cause you problems.
This buildup can lead to decreased fuel mileage, excessive emissions, hesitation, lack of power, stalling and poor acceleration because the carbon buildup on the vehicles sensors does not allow the computer to properly control the air/fuel mixture, which can lead to even further carbon buildup.
Fortunately, this can be addressed by having the fuel system cleaned, a relatively simple process that most garages should be able to do. Chemicals can be flushed through the fuel system that dislodge and clean out the carbon. Some parts, like the Mass Air Flow Sensor may have to be removed and cleaned manually.
The 2001 Camry does seem to have a lot of issues with carbon buildup, it also has a lot of issues with the Idle Air Control Valve sticking. The only job of the idle air control valve is to maintain the idle. The engine’s computer gives the idle air control valve the feedback it needs to hold a constant rpm. If that valve is sticking or not opening and closing when it should because of a failure of the part of carbon buildup, it will lead to an inconsistent idle.
