4A IZ EIAISSIIJN CONTROLS EXHAUST SYSTEMS V EXHAUST GAS RECIHCULATIUN EGR SYSTEM Pap Pap Ellll CTI Swllnli 4 4A l4 Ellll Valvu Vacuum Signal Valm 4A 13 EGR l l y V lv 4 4 4A l6 Exhlltl Ih lr Pmwr Snmr 4 4A l4 EGR Valv 4 4 4A IZ Ganaral 4A IZ EENEME 5A E e e 2 es The EGR Exhaust Gas Recirculation system used wi on all vehicles reduces the formation of oxides of nitrogen NOx by introducing a metered amount of N exhaust gas into the combustion chambers Exhaust E gas is inert will not burn and therefore combustion temperatures are reduced Fewer oxides of nitrogen O are produced at lower combustion temperatures V In 1976 Jeep models the same EGR system is used by all CJ 5 and 7 models and all California Cherokees Wagoneers and Trucks It consists of a diaphragm actuated flow control valve EGR valve a 4 coolant temperature override switch EGR CTO an j exhaust back pressure sensor and connecting hoses E T up 4fig 4A 3 and 4A 9 4 cA u E ron can rom Nationwide except California Cherokees A 2 Wagoneers and Trucks are equipped with the same system but do not use the back pressure sensor In Fil AN Emi V lW V U those units the EGR valve bolts directly to the d Q t f0 f h CTO SW h The EGR cro switch prevents me action mlm en gine temperature reaches a preset level and the back pressure sensor permits EGR action only at increased EGR engine loads thereby improving driveability EGR VALVE 0 The EGR valve mounts on a machined surface at the rear of the intake manifold on V 8 engines and on the side of the intake manifold on six cylinder engines 0 l iivE When the back pressure sensor is used the EGR valve EXHAUST mounts on the spacer which is an integral part of the E BACK back pressure sensor 5 l RE EGR valves are calibrated by the use of differently I OUTER EPORT shaped pintles fig 4A 10 The valve is normally held I e i A i closed by a spring located above the diaphragm fig 4A 11 The valve opens when sufficient vacuum is applied through hoses connecting the CTO switch and the back pressure sensor if used to the EGR vacuum INNER EGR port at the carburetor Q p0m CTG When vacuum overcomes the diaphragm spring pre Z ssure a pintle within the valve is lifted off its seat mom and exhaust gas which reaches the EGR valve through special passages is metered into the intake G MNH manifold Exhaust gas is drawn from the exhaust crossover passage in V 8 engines from an area near fig AA B GR syslog Slpcyllndsr the heat riser in six cylinder engines