Integrated Heating and A/C Regulation, Air Distribution and Front Suspension Information
Integrated Heating and Air Conditioning Regulation (IHKR)
A system similar in design to the IHKA system has been developed for use in the E 34. It provides separate temperature control regulation for both sides of the passenger compartment.
Regulation of air distribution is accomplished with the three slide levers.
Air Distribution
Diagnosis of the system is possible with the BMW Service Tester.
2.5-litre Engine
The "small" 6-cylinder engine (M 20) is used in the 525i with its good power/ weight ratio, high power output, better fuel consumption and favorable effect. on front/rear axle load distribution. The 2.5L engine has a compression ratio of 8.8:1 and runs on unleaded regular grade fuel with an octane rating of 87 AKI (91 RON).
Digital Motor Electronics (version 1.3) are used utilizing new technologies and incorporating new functions.
^ An inductive engine speed sensor determines engine speed by reading the incremental toothed ring on the vibration damper.
^ Cylinder identification is by an induction coil on the ignition lead of cylinder 6.
^ Fuel injection is semi-sequential by cylinder groups.
^ An emergency-run program and formation of substitute values is possible in the event of sensor signals not being transmitted to the control unit.
^ Adaptive (self-correcting) idle speed control is also incorporated.
^ Fuel cutoff speed when coasting is reduced to 1120-960 rpm, depending on engine load.
^ Self-diagnosis with permanent signal monitoring and memorization of faults.
Control units are version coded to limit the number of different units required and improve spare parts supply.
3.5-litre Engine
The improved 3.5L engine introduced in the E 32 provides the power for the 535i.
The standardized air intake system has passages of greater cross-section to improve cylinder filling. Inlet valve diameter has also been increased. New pistons and matching combustion chambers ensure that the maximum energy is extracted from the fuel-air mixture. Double valve springs ensure accurate valve closure and avoid troublesome resonances. The oil filter is accessible from the top to simplify servicing. A spring-loaded tensioner keeps the oil pump chain at a constant tension.
Hydraulically damped engine mountings provide better damping and insulation against engine vibration reaching the body.
The engine has a compression ratio of 9.0:1, and can therefore be run on unleaded regular grade fuel with an octane rating of 87 AKI (91 RON).
Front suspension
Improved double-pivot spring-damper strut front suspension with leading links to feed forces, acting from the front, into the body. A cross-tube provides a rigid connection between the leading links. Large-volume, double-resilient soft rubber mountings are used between subframe and body.
Separate upper spring and damper locating points were incorporated for a noticeable improvement in ride comfort.
Rigid front axle subframe of welded shell construction, with three attachment points on left and right engine support members. Double row ball bearings using the wheel hub as a bearing housing, and requiring no maintenance or adjustment.
New axle pivot location with low steering scrub radius (10.0 mm).
Wider track improves lateral location when cornering.
Close to ideal axle load distribution, with wishbones angled to rear; this also ensures optimum behavior in a crash situation, since the wishbones are located away from the direct impact-absorbing area.