E34, 36
Synthetic Rear-Axle Oil
In addition to the 7 and 8 Series vehicles as outlined in Service Information bulletin 33 01 92 (3667) dated November 1992, the 5 Series vehicles are now also using the synthetic rear-axle lubricant. Please refer to S.I. 33 01 92 (3667) dated September
1993 for complete information.
Performance Improvement to A4S 310R Transmission
318iA (SOP 1/94), 318isA (SOP 1/94), 325iA, 325isA, 325iCA, 525iA, and 525iA Touring
For the '94 Model Year, the above models will be receiving a new version of the now familiar A4S 310R transmission. The new version incorporates lower gear ratios in first
and second gear. Additionally, 2.5 liter models will have a higher stall speed torque converter (approximately 200 RPM increase). The following chart compares the new and previous versions:
1st Gear 2nd Gear 3rd Gear 4th Gear
Old Ratio 2.40 1.46 1.00 0.72
New Ratio 2.86 1.62 1.00 0.72
Due to the increased spacing of first through third gears, this new version may also be referred to as the "widespread gear ratio automatic transmission." Careful selection of gear ratios and torque converter characteristics has enhanced the low-end acceleration
performance of these vehicles without a detrimental effect on emissions or fuel economy.
Adaptive Automatic Transmission Control
530iA, 530iA Touring, and 540iA (SOP 9/93)
Adaptive transmission control has been developed to more closely match the shifting behavior of the 5-speed automatic transmission to the driver's individual style. The adaptive automatic transmission control (AGS) takes various environmental conditions into consideration (car being driven uphill/downhill, slippery road surface, etc.) as well as an assessment of the current driving style (aggressive or economical) before signaling a gear change. By evaluation of both the current environmental conditions and driving style the AGS system ensures the appropriate response from the automatic transmission yielding the following advantages:
- fuel consumption is lower if the car is driven calmly and smoothly
- reduction in the number of gearshifts that take place
- maximize traction and stability on slippery surfaces
- improved driver convenience through the reduction of unnecessary driver inputs (automatic program selection).
Fundamental Logic of the Adaptive Transmission Control System
- if the accelerator pedal is depressed rapidly, a downshift normally takes place
- if the accelerator pedal is released suddenly, the present gear is usually retained
- maintaining a constant speed and accelerator pedal position will
automatically select an economy shift program after not more than 10
AGS System Components

1.Transmission control module
2.Program switch and manual selector lever
3.Engine control module
4. Instrument cluster
5.ASC/ABS control module
6.Automatic transmission
Program Selection
The program switch on AGS equipped cars offers the selection of either the adaptive or manual gear selections. The driver can pre-select the sport program regardless of driving style by moving the manual selector lever to position 4, 3, or 2 when in the 'A'
program. Each time the car is restarted, the 'A' program is automatically selected.
Gear Selection by Program Mode
Selector Lever Program Mode
Position Adaptive Manual
D D - Full Adaptive 4
4 4 - Adaptive Sport 4
Programs Only,
Upshifts 1-4
3 3 - Adaptive Sport 3
Programs Only,
Upshifts 1-3
2 2 - Adaptive Sport 2
Programs Only,
Upshifts 1-2
Gear Selection in the Adaptive Program

Figure 2. Block Diagram of Gear Selection Logic
The AGS system continuously evaluates accelerator pedal position and movement, actual road speed, operation of the kick-down switch and brake light switch, lateral acceleration, and changes in speed during braking to assess the current driving style.
Based on the assessment of the current driving style one of four basic shift programs is selected. The basic shift programs are graduated from the exceptionally economical 'XE' program through the already familiar 'E' and 'S' programs to the exceptionally
sporting character of the 'XS' program. A new assessment of driving style is begun each time the car is driven away from a standstill and the previous assessment is 'forgotten' by the system.
If exceptional ambient conditions are encountered, either of two special purpose programs are selected. For example, when a slippery road surface is encountered, a 'Winter' shift program is used in order to increase traction and the car's dynamic stability. The 'Winter' program encompasses 2nd gear starts with early upshifts and delayed downshifts. When climbing hills or carrying a heavy load, a 'Mountain/Heavy Load' program is used which comprises more performance orientated programs to reduce transmission shift frequency in these conditions.

Figure 3. Automatic Program Selection
XS - Exceptionally Sporting
S - Sport
E - Economy
XE - Exceptionally Economical
Special Purpose Programs
1 - Winter
2 - Mountain/Heavy Load
Factors in Determination of Driver Type for Shift Program Selection
Assessment of starting style
The driver's style when starting from a standstill influences the choice of shift program.
An aggressive start, pressing fast and deep into the accelerator pedal, will bring up a sporting shift map. Moderate to light throttle application will retain an economical shift map.
Kick-fast assessment
A sudden increase in throttle opening angle can provoke a change from an economical program with less frequent shifts to a more sporting, driver-orientated shift program.
This will normally be noticed as a downshift taking place.
Regular driving assessment
If the vehicle is driven at a constant accelerator pedal position, an economical shift program is selected within a maximum of ten seconds. This will typically be noticed as an upshift taking place.
Kick-down assessment
If the 'kick-down' switch is activated, a sport shift program is selected immediately. After the 'kick-down' switch is deactivated the shift program remains biased towards a sporting driving style for a short time.
Braking assessment
Excessively heavy or violent braking causes a change to a sport shift program so that the transmission downshifts earlier, gaining the advantage of engine braking to help slow the vehicle.
Identification of winter conditions
If the driven wheels spin even at a low rate of acceleration, the 'Winter' shift program is selected. The 'Winter' shift program locks-out 1st gear to ensure smoother traction and reduces load-reversal reactions by shifting up earlier. If the wheels no longer spin for several seconds at a high transmitted torque level, the 'Winter' program is exited. The 'Winter' program is also stopped if the ASC system is switched off or if the driver selects the 'Sport' program manually.
Gradient identification
If an uphill gradient is identified (or the vehicle is carrying a heavy load), a special 'Mountain/Heavy Load' shift program is selected. This shift program encourages downshifts as a means of obtaining greater engine power, but prevents repeated
'hunting' between two adjacent gears.
Factors Which Influence the Choice of Gear
Stop-and-go traffic identification (540iA only)
If the vehicle is driven slowly and only accelerated gently between two stops, the transmission shift program will block the downshift into 1st gear. However, this downshift can be provoked by depressing the accelerator pedal further when the full performance potential of the vehicle is needed.
Downhill gradient identification
AGS identifies that the vehicle is on a downhill gradient when the road speed is increasing even though the accelerator pedal is released. In this situation, upshifts will be suppressed in order that engine braking is utilized more effectively. If the driver also
applies the brakes, the transmission downshifts to the next lower gear (RPM permitting) so that engine braking becomes even more effective. If the 'Winter' program has been activated, the downshift does NOT occur.
Fast-off identification
If the accelerator pedal is eased back suddenly, for instance when the driver transfers his foot to the brake pedal, the shift program prevents an upshift if the transmission is in 3rd, 4th, or 5th gear. This ensures that the available engine braking effect is fully
utilized since the driver's action of suddenly easing back on the accelerator pedal is an indication of his intent to slow down the vehicle. This upshift suppression also reduces the number of transmission shifts when the car is driven in a hard or enthusiastic
manner, as historically automatic transmissions upshifted to the highest possible gear when the accelerator pedal was released.
Corner identification
Lateral acceleration is computed by evaluating wheel rotation speeds (using the ABS sensor signals). Based on these calculations, upshifts are inhibited when cornering hard to maintain vehicle stability.