CITROEN XM User Manual

Željko Nastasic´Gábor Deák JahnThe CitroënTechnical Guide

UThe Citroën Guide Fuel Injection: Diesel engines 10Diesel enginesDiesel oil has been a contender to gasoline formany decades. Earlier diesel engines

UThe Citroën Guide Fuel Injection: Diesel engines 11engine but the coupling adds a horizontal, alternatingmovement as well: for each turn, the shaft a

UThe Citroën Guide Fuel Injection: Diesel engines 12rather weak spring Ü. This will rotate the lever Û, movingthe collar 5 to the left, setting the am

UThe Citroën Guide Fuel Injection: Diesel engines 13sure that the amount of fuel injected as well as the timingprovide better combustion and lower pol

UThe Citroën Guide Fuel Injection: Diesel engines 14Towards a cleaner worldExhaust Gas Recycling (EGR) systems were used—depend-ing on the market—as a

UThe Citroën Guide Fuel Injection: Diesel engines 15Electronic Diesel ControlJust like it is the case with gasoline engines and carburetors,a mechanic

UThe Citroën Guide Fuel Injection: Diesel engines 16tentions of the driver. The ECU uses this sensor to learnabout special conditions like idle speed

UThe Citroën Guide Fuel Injection: Diesel engines 17Diesel Direct InjectionI think that at this point, soot burning filters will have to becut out of

Suspension

UThe Citroën Guide Suspension: A Suspension Primer 19A Suspension PrimerFrom the early days of the automobile—and evenbefore, in the time of horse-dra

There are many car manufacturers, makes, modelsand versions on the road today but—as we allknow—none of them compares to Citroën in itsengineering exc

UThe Citroën Guide Suspension: Hydropneumatic Suspension 20Hydropneumatic SuspensionAs we saw, the ideal suspension would requireelasticity decreasing

UThe Citroën Guide Suspension: Hydropneumatic Suspension 21The steady connection between the sides requires an ex-ternal management of body roll. Idea

UThe Citroën Guide Suspension: Hydropneumatic Suspension 22Finally, there are no forces in the suspension when the cir-cuit is depressurised, allowing

UThe Citroën Guide Suspension: Hydropneumatic Suspension 23With the back pressure now vanished from behind thepiston 1, the pressing force of the accu

UThe Citroën Guide Suspension: Hydractive I 24Hydractive IThe Hydractive I suspension system appearedwith the XM. Unlike the simpler hydropneumaticsus

UThe Citroën Guide Suspension: Hydractive I 25While the computer keeps the suspension in soft mode,the electro-valve 5 is energized by the ECU, openin

UThe Citroën Guide Suspension: Hydractive I 26strument panel informs about the setting selected (it doesnot indicate the mode the suspension is curren

UThe Citroën Guide Suspension: Hydractive I 27call for hard mode, the suspension will revert within50 ms and restart the one-minute timeout period;Ube

UThe Citroën Guide Suspension: Hydractive I 28and tailgate open sensors) , leaving the electro-valve en-ergized for the duration of the timeout.It is

UThe Citroën Guide Suspension: Hydractive II 29Hydractive IIThe second incarnation of the hydractive suspen-sion appeared at February 1, 1993 (ORGA 59

Table of ContentsFuel InjectionElectronic Fuel Injection . . . . . . . . . . . . . . . 5Diesel engines . . . . . . . . . . .

UThe Citroën Guide Suspension: Hydractive II 30lets the pressure inside the center sphere 1 move the con-trol piston into a position which closes off

UThe Citroën Guide Suspension: Hydractive II 31Vehiclespeed(km/h)Pedal press rate(steps/25 ms)Vehiclespeed(km/h)Pedal release rate(steps/25 ms)Normal

UThe Citroën Guide Suspension: Anti-sink system 32Anti-sink systemMany contemporary Citroëns—including both reg-ular hydropneumatic and Hydractive Xan

UThe Citroën Guide Suspension: Activa Suspension 33Activa SuspensionThe Activa suspension—used only on some Xantiamodels—creates mixed feelings. Drive

UThe Citroën Guide Suspension: Activa Suspension 34spheres, and making the coercive force be applied througha spring element which becomes progressive

UThe Citroën Guide Suspension: Hydractive 3 35Hydractive 3The new C5 has a new suspension system, doingaway with many solutions used on Citroëns forse

UThe Citroën Guide Suspension: Hydractive 3 36As usual with Citroëns, the driver can select from fourheight settings (although the selector is no long

Steering

UThe Citroën Guide Steering: Power Assisted Steering 38Power Assisted SteeringThe PAS steering (DIRASS, Direction Assistée)used on Citroëns is not rad

UThe Citroën Guide Steering: Power Assisted Steering 39into the reservoir via the rotor of the controlvalve. This pressure difference moves the pis-to

Fuel Injection

UThe Citroën Guide Steering: DIRAVI Steering 40DIRAVI SteeringAnother gem of engineering, the DIRAVI steering,made its debut on the SM, excelled in ma

UThe Citroën Guide Steering: DIRAVI Steering 41Thus, the lower mechanical link, the feedback from theroadwheels does not extend beyond the hydraulic u

UThe Citroën Guide Steering: Self-steering Rear 42Self-steering Rearsasasa

Brakes

UThe Citroën Guide Brakes: Standard braking system 44Standard braking systemdasdsadsa3) Back to the suspension and brakes for a second. The rearsinks

UThe Citroën Guide Brakes: Anti-lock Braking System 45Anti-lock Braking SystemModels with higher performance level came fittedwith ABS.The principle o

ElectricalSystems

UThe Citroën Guide Electrical Systems: Multiplex network 47Multiplex networkCircuit layouts already universally adopted in com-puters finally made the

UThe Citroën Guide Electrical Systems: Multiplex network 48Each message or command is a sequence of a few num-bers, specifying:Uthe sender and the int

Air Conditioning

UThe Citroën Guide Fuel Injection: Electronic Fuel Injection 5Electronic Fuel InjectionThe Otto engine needs a mixture of fuel and airfor its operatio

UThe Citroën Guide Air Conditioning: Air conditioning 50Air conditioningOnce considered pure luxury, air conditioning andother forms of climate contro

UThe Citroën Guide Air Conditioning: Air conditioning 51The sensor before and in the heat exchanger as well asthe teperature selection, influence the

Appendix

UThe Citroën Guide Appendix: 53ORGA numberThis number shows the day when your car was actually as-sembled on the production line. The dealers and part

Index

UThe Citroën Guide Index: 55IndexAAV . . . . . . . . . . . . . . . . . . . . . . . . . . 7ABS. . . . . . . . . . .

UThe Citroën Guide Index: 56Idle speed . . . . . . . . . . . . . . . . . . . . . . . 6idle speed control valve . . . . . .

UThe Citroën Guide Fuel Injection: Electronic Fuel Injection 6hardly ideal for any reasonable amount of time, several cor-rections have to be applied.

UThe Citroën Guide Fuel Injection: Electronic Fuel Injection 7see whether this is a cold start or a warm one. If the coolantfluid is measured cold, a

UThe Citroën Guide Fuel Injection: Electronic Fuel Injection 8eration—, the momentum of the car is sufficient to rotatethe engine through the wheels.

UThe Citroën Guide Fuel Injection: Electronic Fuel Injection 9Both changes have to do with the fact that the enhancedsystem, whose new task is to gene