Method for operating an internal combustion engine

In a motor vehicle having an internal combustion engine, said engine comprising a plurality of combustion chambers, an induction manifold for supplying air to the combustion chambers, at least one arbitrarily controllable throttle valve for controlling the air supplied to the manifold, the manifold including one short pipe for each chamber, one long pipe for each chamber and a means for switching between the short and long pipe for tuned induction pressure charging, a method for operating the engine comprising the steps of:

• determining the pressure of the air fed to the manifold by the at least one throttle valve;
• monitoring the switching means of the induction manifold for maladjustment;
• upon maladjustment, outputting an error message;
• and
• intervening with the engine control, and
• wherein the step of monitoring the switching means comprises the steps of:
• predetermining a regular combustion air flow rate;
• determining the actual combustion air flow rate in the induction manifold;
• and
• comparing the actual flow rate to the regular flow rate;
• upon determining that the actual flow rate is less than the regular flow rate, indicating a maladjustment, and
• wherein said internal combustion engine has fuel injection and engine capacity is computed using the following equation:
• .lambda..sub.a =K(m/n)
• where
• .lambda..sub.a =engine capacity,
• K=a constant
• m=air mass/amount
• n=engine speed;
• wherein the step of monitoring the switching means comprises the steps of:
• determining a regular capacity value of the engine,
• determining an actual capacity value of the engine;
• comparing the actual capacity value to the regular capacity value;
• and
• upon determining that the actual capacity value is less than the regular capacity value, reporting a maladjustment, and
• wherein the step of comparing the actual capacity value to the regular capacity value comprises the steps of:
• generating at least one capacity curve of the induction manifold comparing the capacity .lambda..sub.a to the engine speed n;
• storing the at least one capacity curve in an operating map;
• comparing the desired capacity value to the actual capacity value using the at least one capacity curve;
• and
• upon determining that the actual capacity value is less than a predetermined threshold value, reporting a maladjustment.