Abstract: A warning system for an air-fuel ratio control system for a electronic controlled internal combustion engine, where a basic fuel injection amount is corrected by a feedback correction factor determined by a signal from an air-fuel ratio sensor arranged in an exhaust pipe. An amplitude of the feedback correction factor caused by an acceleration of the engine, where the exhaust from cylinders is not completely mixed, is detected, and a warning can be given when the amplitude of the feedback correction factor is larger than a predetermined value. A malfunction in the air-fuel ratio system occurring in one cylinder can be detected. In a double O.sub.2 sensor system, where a sub-feedback loop is provided for correcting the feedback correction factor in accordance with a signal from the second O.sub.

Abstract: A diagnosis device for an exhaust gas recycling device diagnoses whether or not an exhaust gas recycling device is operating normally; the temperature of an exhaust gas recycling passage is detected by a temperature detection means, a decision is made by an exhaust gas recycling operating region detection means whether or not the operating region is such as to carry out exhaust gas recycling, when a decision is made that the operating region is such as to carry out exhaust gas recycling a counter is incremented and when otherwise is decremented, and a decision that the exhaust gas recycling is not being carried out normally, that is that the exhaust gas recycling device has failed, is made when the count value of this counter is at least a certain value and the temperature of the exhaust gas recycling passage is not more than a certain value.

Abstract: An altitude compensation device for a carburetor including a chamber in communication with the atmosphere, an air bleed port conducting atmosphere from the chamber, a primary conduit providing fluid communication between the chamber and the fuel system of the carburetor, a first valve responsive to changes in atmospheric pressure for opening and closing the air bleed port, a first flow restrictor in the primary conduit downstream of the air bleed port, an auxiliary conduit providing fluid communication between an atmospheric pressure source and the primary conduit at a junction downstream of the flow restrictor and upstream of the carburetor fuel system, a second valve responsive to changes in atmospheric pressure controlling communication between the auxiliary conduit and the atmospheric pressure source, a second flow restrictor in the auxiliary conduit downstream of the atmospheric pressure source and upstream of the junction with the primary conduit, and a thermosensitive valve responsive to engine tempera