DISA is used also in other/previous BMW engines, not only N43/N53, so here we will mention only nuances, which are topical exactly for these engines.
In the image: location of DISA valves of N53B30 O0
In the image: status of DISA valves for N53B30 O0 (the most powerful version, installed on models 330i/530i/630i) depending on RPM. These engines have intake with two DISA valves, which are opening one after another, depending of RPM.
In the image: DISA valve connection of N53B30 O0. The power supply comes from fuse F03, control signal – from DME pin 18 and 40.
The N53 series engine is very interesting – it has following numbers of DISA valves:
1 piece: N53B25
0 piece: N53B30 U0 (160kW)
2 pieces: N53B30 O0 (200kW)
Intake manifold, number of DISA valves and software version are only differences between N53B30 U0 and O0. More about the upgrade from U0 to O0 read here.
It is interesting, that the version of the engine (U0 or O0) is defined in status bits power_class, which is stored in DME and CAS, but, not taking it into account, also software version is defined for use with U0 or O0.
power_class = 0: N53B30 U0
power_class = 2: N53B30 O0
Version 8603152 is intended for N53B30 U0 – it will not “see” and will not control (manage) DISA valves, even if they will be installed (after upgrade of the engine to most powerful version).
Version 8603178 is intended for N53B30 O0 – it, in turn, provides management of DISA valves. If DISA valves are not connected (for example, attempt to increase the power by modifying software, but not modifying the intake manifold), DME records error message regarding DISA valves, switches to emergency mode and very significantly decreases the power.
If the modification of the inlet manifold is performed and software version O0 is programmed, DME will not record error messages regarding DISA valves, but (in the situation, if the power_class still is U0) don’t manage DISA valves, and the performance is even worse than for version U0. Only after modifying power_class, DME will start to manage DISA and develop the intended power.
How to make sure, that the upgrade of the engine was successful?
The opening of DISA valves can be felt very well when accelerating rapidly – slightly below 4000 RPM and above 5000 RPM the increase of torque can be felt.
Examination (especially required after increasing the power of the engine):
1. disconnection of any DISA valve immediately registers the corresponding error message in MSD80 error message memory. This is a signal, that MSD80 “sees” DISA valves;
2. using INPA ../F6/F1/Shift + F4
a) evaluate DISA valve counters: they show, how many times each of DISA valves has opened. If after the driving session (when 5000+ RPM are reached) the counter is 0 – DISA valves, obviously, are not used;
b) status: ignition = on/engine = off (value of deactivated DISA valve: 10%). Using manual management, activate DISA valves. It can be heard from the intake manifold, how DISA valves are opening/closing. If it’s not possible to hear status change of DISA valves due to background noise;
c) except one DISA valve, using INPA, open/close the valve manually – make sure, that DISA works;
d) performing the driving session, slightly below 4000 RPM, the valve No.2 will open; above 5000 RPM also valve No.1 will open – the opening will be confirmed with corresponding PWM values.
Note: after finishing the manual operation test, don’t forget to turn back DISA manual management to DME management (if it will not be done, manually confirmed position of DISA will be stored also for future driving sessions).