초록 ▼

A method according to the present invention controls engine roughness by varying the ethanol content in a fuel mixture of a flexible fuel vehicle. Initially, a trigger threshold and fix threshold are established based on engine speed and manifold pressure. The fix threshold is less than the trigger

A method according to the present invention controls engine roughness by varying the ethanol content in a fuel mixture of a flexible fuel vehicle. Initially, a trigger threshold and fix threshold are established based on engine speed and manifold pressure. The fix threshold is less than the trigger threshold. A first ethanol amount is delivered to the fuel mixture if a first measured roughness is greater than the trigger threshold. A second measured engine roughness is determined after delivering the first ethanol amount. The delivery of the first ethanol amount is stopped if the second measured roughness is greater than the trigger threshold. A second ethanol amount is delivered if the second measured roughness is less than the trigger threshold but greater than the fix threshold. A third measured roughness is then determined. Delivery of the second ethanol amount is stopped if the third measured roughness is greater than the trigger threshold. The roughness is measured and ethanol delivery modified accordingly so long as the third measured roughness is less than the trigger threshold and greater than the fix threshold.

대표청구항 ▼

[ What is claimed is:] [1.]1. A method for ethanol content learning based on engine roughness comprising the steps of:establishing a trigger threshold based on engine speed and manifold pressure;establishing a fix threshold based on engine speed and manifold pressure;obtaining a first measured engin

[ What is claimed is:] [1.]1. A method for ethanol content learning based on engine roughness comprising the steps of:establishing a trigger threshold based on engine speed and manifold pressure;establishing a fix threshold based on engine speed and manifold pressure;obtaining a first measured engine roughness;incrementing fuel delivery by a first ethanol amount if a first measured roughness is greater than said trigger threshold;obtaining a second measured engine roughness after incrementing fuel delivery by said first ethanol amount;decrementing fuel delivery by said first ethanol amount if said second measured roughness is greater than said trigger threshold;incrementing fuel delivery by a second ethanol amount if said second measured roughness is not greater than said trigger threshold but greater than said fix threshold;obtaining a third measured roughness after incrementing fuel delivery by a second ethanol amount; anddecrementing said fuel delivery by said second ethanol amount if said third measured roughness is greater than said trigger threshold.