Abstract: An apparatus for carrying out the calibration of engines having a Bosch L-Jetronic electronic injection apparatus which is provided with an electronic control unit connected to a "lambda" probe inserted in the exhaust pipe for the closed loop control for carburetion includes a circuit for determining the difference between the value of a correction signal when the probe is switched into the circuit and the value of the correction signal when the probe is switched out of the circuit and a display device for providing a visual display of the difference.

Abstract: A four cylinder spark ignition internal combustion engine has an exhaust emission control system including means for admitting fresh air into the exhaust system in order to promote a further combustion of partly burnt components in the gases coming from the combustion chambers, this means include a "reed" valve connected to the exhaust ports leading from the first and fourth cylinders (numbering from one end of the engine) through internal passages within the cylinder head; the system also comprises an exhaust gas recirculating system comprising a pneumatic valve which opens, when the conditions are appropriate, to draw off a proportion of the exhaust gases from the exhaust side of the engine and admit them to the induction side of the engine taking exhaust gases from branches of the exhaust manifold carrying exhaust gases from the second and third cylinders; in addition there is a system for admitting supplementary air to the induction manifold downstream of the carburettor during engine overrun conditions e

Abstract: An exhaust emission control system for a spark ignition internal combustion engine comprises a first pressure sensitive valve for recycling a proportion of the exhaust gases from the exhaust to the induction when the engine is warm, being inhibited when the engine is cold, valves for admitting a small amount of fresh air to the exhaust manifold, a second pressure sensitive valve for admitting fresh air to the induction manifold downstream of the carburettor when the engine is warm, being closed when the engine is cold and when the starter motor is energized, a first fuel/air mixture enrichment valve in the carburettor sensitive to induction manifold pressure and de-sensitized when the engine is cold, a second fuel/air mixture enrichment valve sensitive to induction manifold pressure and de-sensitized when the engine is hot, and a vacuum advance delay which is by-passed when the engine is warm.

Abstract: A spark ignition internal combustion engine having an exhaust emission control system including an air pump driven by the engine to pump fresh air directly into the exhaust duct in order to promote a further combustion of partly burnt components in the gases coming from the combustion chambers, excess air pressure being released by a pressure relief valve into an air filter for the induction air; the system also comprises an exhaust gas recirculating system comprising a pneumatic valve which opens, when the conditions are appropriate, to draw off a proportion of the exhaust gases from the exhaust side of the engine and admit them to the induction side of the engine; in addition there is a system for admitting supplementary air to the induction manifold downstream of the carburettor during engine overrun conditions except when the engine is cold, and the carburettor is provided with supplementary pumps and valves which only function when the engine is cold, being inhibited as the engine approaches its normal w