Details of Tata Indica / Indigo ECU Hello,
In one of my earlier posts i disagreed with Tsk 1979 who had mentioned about a 32 bit processor in tata indigo diesel .i was under the impression that IDI engines dont need ECU .Tata has done a wonderful job by using a ecu for the fuel pump and a cost effecive way to taclkle the stringent emission norms. I was wrong Tsk . found some details from indica users group. hope it will be useful .
Moderators pls post this in a appropriate forum
Type No---475 IDI Euro-3
Make------Lucas TVS
Primary Functions :---
1. Fuel pump injection timing control.
2. Glow plug pre & post heat control.
3. EGR system on-off control.
Secondary Functions :---
1. FICD (Fast Idle Control Device Control). This is
the device which
increases the rpm when the AC is switched on.
2. AC switch off at high Engine temperature and high
loading.
3. High altitude proportional control.
4. Fault detection & storage of trouble codes.
The ECU gets its inputs / information about Throttle
position, coolant
temperature, ambient temperature, engine rpm,
crankshaft angle & Injection
start from the following sensors on the engine :
1. Throttle Position Sensor or Fuel Lever Sensor :
This is a potentiometer connected to the fuel delivery lever which is
actuated when the accelerator
pedal is pressed. It sends a DC voltage to the ECU which is proportional to
the accelerator postition.
2. Temperature Sensor : This is a thermistor type of
sensor, monitoring thecoolant temp.
3. RPM sensor : Part of the alternator. Gives 3
voltage pulses for one revolution of the crankshaft.
4. Crankshaft Angle Sensor or Crankshaft Position
Sensor. This is moumted onthe flywheel housing, and provides piston TDC (Top
Dead Centre) information to the ECU, in the form of number of voltage pulses
per 90 degrees angle of rotation.
5. Needle Lift Sensor : This sensor is part of No. 4 cylinder fuel injector,
& sends a voltage signal to the ECU at the precise beginning of injection.
How it works :
Based on the inputs from these sensors, the ECU
controls the following units
through Relays, Solenoid switches & PWM control :
1. Glow Plug Heaters : These are for pre-heating the
cylinders. The ECUcontrols the glow plugs ON time based on ambient &
engine temperature.
2. Fuel Pump: Injection timing is controlleddepending on the position of
the accelerator pedal----timing is advancedautomatically at higher rpm. The
ECU controls a cam actuator inside the fuel pump,
based on a look up table stored in the ECU program ROM.
3. EGR : This is the Exhaust Gas Recirculation
system. Part of the exhaust
gases are mixed with the air intake to reduce temperatures inside the
cylinders to below 210 deg C., which sharply
reduces the formation of Nitrogen Oxides (Nox) in the exhaust, thereby
reducing harmful pollutants as reqd. by Euro / BS 2 & 3 norms.The EGR valve is
controlled by the ECU, & gets activated in the rpm band 1100 to 3000 rpm,
with small variations to compensate for engine temp & loading.
4. FICD : The fast idle control is used to increase
the idle rpm when the AC is switched on. The ECU activates the FICD through a
solenoid switch by monitoring the AC compressor clutch voltage.
The ECU also continuously monitors the engine
temperature, & switches offthe AC if upper limits are exceeded.
All the sensors are also monitored continuously, and
a fault or troublecode is stored in non-volatile memory in case of a
fault, & the Check Engine Light comes ON. |