Nissan Qashqai J11. Manual - part 182

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SYSTEM

Air Conditioning Power

The amount of power absorbed by the air conditioning is useful for the engine control to compute the torque
requirement for air conditioning. Therefore, ECM can adapt dynamically the engine speed regulation depend-
ing on the load variations.
The power absorbed by the air conditioning depends on the refrigerant pressure and the compressor speed.
The air conditioning system power correction for idle speed regulation avoids engine speed undershoots and
overshoots at the compressor compressed volume variation.

Alternator

ECM controls idle speed depending on charge status of alternator.

MINIMUM AVAILABLE TORQUE

The minimum available torque is used for the minimum driver set-point calculation and the intersystem infor-
mation.
The minimum torque is designed with a hyperbolic shape depending on the difference between the engine
speed and the idle speed set-point:
• When the engine speed is under the idle speed set-point, the minimum torque is equal to the hyperbolic

torque which increases to avoid an engine stalling.

• When the engine speed is over an engine speed threshold, the minimum torque reaches the torque for the

minimum manifold pressure with a ramp.

The torque for the minimum manifold pressure is designed to avoid any oil consumption (oil vapor back up in
the intake manifold).
It is estimated in function of the engine capacity displacement, the manifold air volume, the manifold air pres-
sure, the manifold air temperature, the cylinder fill-up efficiency, the ignition efficiency and the number of cylin-
ders. It is corrected in function of the coolant temperature to avoid ‘poor combustion’.
When the engine starts, a specific torque set-point is calculated to ensure the engine start. This torque is
dependent of the engine speed and the coolant temperature.
At first, a calculation of the starting torque value is performed. In case of a difficult start (too long), this torque
may be increased thanks to ramp.
The start torque offset is progressively set to zero to ensure a transition with the current torque set-point.

MAXIMUM AVAILABLE TORQUE

The maximum available torque results of a minimum selection including all powertrain constraints:
• Transmission torque limitation
• Maximum engine torque
• Torque reduction for the heating protection
• Low gasoline level in the tank

Transmission torque limitation

This limitation is the maximum torque to protect the transmission from a mechanical overload:
• For a manual transmission, the limitation value of the torque is function of the engine speed and the trans-

mission ratio.

• For an automatic transmission, the limitation value is directly supplied by the automatic transmission.

Maximum engine torque

The maximum torque depends on the engine speed and fail-safe mode of the throttle valve. This limit is com-
puted and corrected with:
• Number of available cylinders
• Intake air temperature
• Atmospheric pressure
• Engine speed
• Over-torque limit
• Torque losses (friction, pumping, etc.) to calculate the maximum effective engine torque

Torque for the heating protection

This torque limit is dedicated to the protection of the engine from an overheating. It depends on the engine
speed, the engine coolant temperature, the intake air temperature and the vehicle speed.

Protection torque

This torque is computed in function of the low gasoline level in the tank and the engine speed.

Fail-safe

The ECM limits a engine torque in case of malfunction of engine component or ECM.

SYSTEM

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Depending on the engine components, ECM activates the fail-safe mode of the torque limitation level 1 (low
limitation) or level 2 (mean limitation).

FAST SET-POINTS TO COMPLETE TORQUE REQUEST

This control aims to compute:
• The number of cylinders to cut
• The final ignition advance calculated by the torque structure without limitations
• The final ignition advance calculated by the torque structure
In function of:
• The final indicated torque set-point
• The final indicated target torque
• The fresh mass air flow
The torque efficiency correction is calculated to compensate the fact that the target torque request cannot be
realized by the throttle full opening.
In deceleration and in engine over speed, the cutting of the all injectors is authorized. In a limp-home mode,
the number of cylinders to cut is limited.

SLOW SET-POINTS TO COMPLETE TORQUE REQUEST

This control computes:
• The fresh air mass flow set-points passing through the engine
• The fresh air mass flow set-points passing through the throttle
• The torque efficiency corresponding to the maximum ignition advance
• The torque efficiency for the idle speed control
• The correction of the torque efficiency for the catalytic converter warm-up
The torque efficiency for idle speed control is function of the idle speed set-point and the engine air load.
The correction is applied when the engine is running autonomous and when one of the following catalytic con-
verter warm-up phases is in action: the catalytic converter warm-up by exhaust air injection, the catalytic con-
verter heating in progress, the lean burn catalytic converter heating conditions or the richness distribution.
The correction takes into account the type of transmission and the Park/Neutral state for an automatic trans-
mission, the starting coolant temperature and is adapted to the duration of the catalytic converter warm-up.

FINAL TORQUE REQUESTS SETTING

The final torque requests are computed by the arbitration with the driver request, the intersystem torque
request (ESP), the torque limitations and the curative anti-jerk correction.

INJECTION CUT

When no torque is requested by the driver, the injection is cut to reduce the fuel consumption if the following
conditions are met:
• The engine is in autonomous state after a delay function of the coolant temperature
• The coolant temperature is over a threshold
• The engine speed is over a minimum engine threshold and above a maximum engine threshold
• There is no intersystem request

FULL LOAD

When the driver torque is on the maximum available torque and the kick-down detected, the throttle is full
opened.
For turbocharged engines, the full load is also activated when the driver torque request is greater than the
threshold above which controlled the wastegate.
The full load is disabled when the turbocharger is out of order or if we have an intersystem torque request in
progress (ABS/TCM).

TORQUE CORRECTION IN THE KNOCK ZONE

For the protection of boost engines against the knock, it is necessary to correct the engine load: limitation of
opening throttle. The only use of the ignition correction during the overfeed phase, generates a rise in the
exhaust temperature and consequently a rise in the energy to the turbine.
This supplementary energy generates an overfeed pressure increase hence increasing the knock zone phe-
nomenon risk. This strategy decreases the load by decreasing the torque driver request.

COMBUSTION CONTROL

COMBUSTION CONTROL : System Description

INFOID:0000000010379031

SYSTEM DESCRIPTION

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SYSTEM

A gasoline engine needs ignition coils: it is a piloted ignition.
The wished torque set-point is realized with the two following settings:
• Fuel quantity injected
• Ignition set point
Others parameters are also taken into consideration for different reasons such as acoustic, performance and
emissions:
• Richness (ratio between fuel and air quantities)
• Injection phasing
The following illustration shows general combustion functioning on an engine cycle.

The engine and vehicle conditions can provoke a poor combustion also called misfire, which is detected by an
OBD strategy.
Misfire diagnosis specifies the function for misfires detection through software “torque-meter”:
It corresponds to the analysis of a cylinder on which there is no combustion. The reason for the misfire can be
a wiring or mechanical combustion necessary component default (injector, ignition coil, spark plug) resulting in
a lack of compression in the same cylinder. The diagnosis is also able to detect an occasional dysfunction on
a cylinder.
The ECM detects two types of misfire:

Catalytic Converter Misfire

The aim is to detect large misfire rates, which provoke a rise of temperature in the catalytic converter suscep-
tible to damage it. The misfire rates that must be detected are variable according to the working point (by 2D
calibration). The malfunction indicator lamp (MIL) should blink immediately.
Besides the function has to allow the most accurate identification the misfiring cylinders, and set an alert flag
to inhibit the functional diagnoses of the exhaust line (probe, three way catalyst, engine oil system, fuel sys-
tem) in order to avoid false diagnoses.

Pollution Misfire

The aim is to detect small misfire rates. This detection has to be effective during the certification cycle test.
The malfunction indicator lamp (MIL) must lighten before the end of a defined number of driving cycles with
the current defaults.

JPBIA5637GB

SYSTEM

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MANAGEMENT OF THE FUEL ALIMENTATION

The fuel pump insures the fuel supply. It is activated at every key-on for one-second duration. It insures a min-
imal pressure level in the circuit and enables to obtain a correct start, especially after a long period without use
of the vehicle.
When the engine is running, the relay is always commanded, so the pump is always active.
The setting with the atmosphere of the gasoline tank is carried out through a EVAP canister, which is filled with
active charcoals. These active charcoals catch the gasoline vapors. The vacuum pressure engine performs
the purging of EVAP canister. It flows in the intake filling session, through a hose whose section is controlled
by a EVAP canister purge volume control solenoid valve. EVAP canister purge volume control solenoid valve
is driven by the ECM. For noise reason, two frequencies are available to control the EVAP canister vent con-
trol valve.
• A slow frequency (8Hz)
• An high frequency (20 Hz)
The EVAP canister is purged as soon as the activation conditions are OK, in order to limit vapor fumes in the
atmosphere, as it happens when the EVAP canister is saturated.
Vacuum pressure regulation is mechanical and not driven by ECM.

ADVANCE/MANAGEMENT OF THE IGNITION

The management of ignition allows to manage the quality of combustion and so the engine performances.
For a positive advance, the ignition set point is before TDC (top dead
center), nevertheless the advance can take negative values.
The more the optimal advance is away from the TDC, the more the
performances increase. So, the optimal advance is the best value to
optimize the combustion.
The ignition is realized by ignition coils in order to ignite cylinders.
Besides, if there is some detected failure on ignition coils (short cir-
cuit to ground, short circuit to battery or open circuit) a cut request
for the corresponding injectors is managed.
A lack of efficiency could be felt in some specified conditions like
engine over heat or hot atmospheric conditions or a low RON
(Research Octane Number) Fuel. Indeed, it will provoke a knock
phenomenon detected by stronger noise combustion.
This noise is detected by an accelerometer only during the combustion window.

RICHNESS REGULATION

JPBIA5638GB

JPBIA5639GB