Chapter 1 Routine maintenance and servicing

4E•1Chapter 4 Part E:Exhaust and emission control systemsContentsCatalytic converter - general information and precautions . . . . . . . . 4Emission control system check . . . . . . . . . . . . . . . . . . . .See Chapter 1Evaporative emissions control system - checking and componentrenewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Exhaust manifold - removal and refitting . . . . . . . . . . . . . . . . . . . . . 3Exhaust system - renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Degrees of difficultyEasy, suitable fornovice with littleexperience1Fairly easy, suitablefor beginner withsome experience2Fairly difficult,suitable for competentDIY mechanicExhaust system check . . . . . . . . . . . . . . . . . . . . . . . . . . .See Chapter 1General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Positive crankcase ventilation system - checking and componentrenewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Pulse-air system - checking and component renewal . . . . . . . . . . . 7Underbonnet check for fluid leaks and hose condition . .See Chapter 13Difficult, suitable forexperienced DIYmechanic4Very difficult,suitable for expert DIYor professional5SpecificationsTorque wrench settings Nm lbf ftPulse-air system piping sleeve nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 24Exhaust manifold to cylinder head:HCS engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 17CVH engines (non turbocharged) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 12CVH engines (turbocharged) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 to 31 21 to 23PTE engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 12Zetec engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 124E1 General informationExhaust systemThe exhaust system is composed of anexhaust manifold, the front downpipe andcatalytic converter (where fitted), and a mainsection incorporating two silencers. Theservice replacement exhaust system consistsof three sections: the front downpipe/catalyticconverter, the intermediate pipe and frontsilencer, and the tailpipe and rear silencer.The system is suspended throughout its entirelength by rubber mountings.Emission control systemsTo minimise pollution of the atmospherefrom incompletely-burned and evaporatinggases, and to maintain good driveability andfuel economy, a number of emissions controlsystems are used on these vehicles. Theyinclude the following:a) The engine management system(comprising both fuel and ignition subsystems)itself.b) Positive Crankcase Ventilation (PCV)system.c) Evaporative emissions control (EVAP)system.d) Pulse-air (PAIR) system.e) Catalytic converter.The operation of the systems is describedin the following paragraphs.Positive crankcase ventilation systemThe function of the crankcase ventilationsystem is to reduce the emissions ofunburned hydrocarbons from the crankcase,and to minimise the formation of oil sludge. Byensuring that a depression is created in thecrankcase under most operating conditions,particularly at idle, and by positively inducingfresh air into the system, the oil vapours and“blow-by” gases collected in the crankcaseare drawn from the crankcase, through the aircleaner or oil separator, into the inlet tract, tobe burned by the engine during normalcombustion.On HCS engines, the system consists of avented oil filler cap (with an integral meshfilter) and a hose connecting it to a connectoron the underside of the air cleaner housing. Afurther hose leads from the adapter/filter tothe inlet manifold. Under conditions of idleand part-load, the emissions gases aredirected into the inlet manifold, and dispensedwith in the combustion process. Additional airis supplied through two small orifices next tothe mushroom valve in the air cleanerhousing, the object of which is to prevent highvacuum build-up. Under full-load conditions,when the inlet manifold vacuum is weak, themushroom valve opens, and the emissionsare directed through the air cleaner housing1595Ford Fiesta Remake