Control system for engine and transmission using two power modes

Abstract

A control system for a vehicle with an automatic transmission in which the gear ratio is automatically changed in accordance with the operating condition of the vehicle includes a control means set for at least a first range if air-fuel ratios to be determined in accordance with engine speed and a second range of air-fuel ratios for controlling the air-fuel ratio of the engine to enrich a fuel mixture more than in the first range of air-fuel ratios. A shift control system has a first shift characteristic setting means for setting a first shift characteristic, and a second shift characteristic setting means for setting a second shift characteristic such that an upshift is effected in a higher vehicle speed range than that in the first shift characteristic. A characteristic changing means selects the first shift characteristic during ordinary driving (i.e. non-power driving) and the second shift characteristic during a specific operating condition. An air-fuel ratio changing means expands the first range of air-fuel ratios toward the high-speed side of engine operation when the second shift characteristic has been selected by the characteristic changing means to narrow the second range of air-fuel ratios. Thus, when an acceleration force is demanded during ordinary driving, the vehicle is driven to gain a sufficient acceleration force, and at the same time the air-fuel ratio enrichment control is restrained to control the worsening of fuel economy.