950 c temperature until the engine has achieved a smooth operating temperature it is estimated that pulses of 40 60 watts per plug will maintain the glow plugs at their desired operating temperature until the engine starts and reaches operating conditions using a predetermined power value wattage and the measured voltage the microprocessor can calculate the pulse width and spacing to be applied to each individual glow plug 30 to maintain each individual plug at the desired operating temperature an acceptable afterglow duty cycle can be calculated using the formula 50 watts times 1 8 ohm divided by the measured voltage squared the microprocessor 20 will sequentially activate the individual buffers 22 to deliver the required power pulse to each glow plug in sequence as the current to one plug is being turned off the next plug in sequence will be turned on so the sequencing procedure will maintain a nearly constant current flow to the glow plugs throughout the after glow cycle sequentially applying current the plugs in a rotating fashion will smooth the current flow by reducing current surges and thereby reduce emi surges resulting from current flow variations it will also prevent current surge drains on the battery system which were the result of operating systems utilizing temperature controlled relay systems it is expected the afterglow pulses will generally be applied to the glow plugs for 1 to 2 minutes after the pre glow cycle is complete this after glow cycle will assist in smoother starting and.