[amitpunjani]

Hi there

When Daewoo launched its first car Cielo, there was alot of hype about fixing the multi point injection cars. Alot of people infact including mechanic still have a notion that MPFI cars difficult to repair and the problem could not be rectified in authorised service stations.
Believe me its not difficult at all, atleast not for Maruti owners as maruti has system by which the faults of the sensors could be diagonised and rectified. Yes the owner will surely have to pay for the faulty sensor but will atleast end up saving the labour and VAT charges.

Here are list of few sensor which are deployed in Maruti Zen and there brief explanation of their function

• Engine Control Unit or Module- This is the brain of all the sensors. It is nornally located underneath the dashboard of the co-driver side.All the sensors sends the signals to the ECM which in turn sends the signals to the sensors for their functioning. The numbers 8 bit or 16 bit or 32 bit are associated with its capacity of ECM to performs the functions.
• Mainfold Absolute Pressure Sensor or MAP sensor- The MAP sensor introduced in mid 1980's, porvides information to the ECM (electronic control module) that accounts for the airflow's rate, temperature and humidity and airflow mass.
• Throttle Position Sensor or TPS- This located on the throttle body. It controls the amount fuel which is injected to the cylinders through the injectors.
• Oxygen Sensor or O2 Sensor or Lambda Sensor: This sensor is mounted on the runners of the exhaust mainfold. it is almost identical to a spark plug. The sensor controls the emissions of the vehicle, by sensing the amount of oxygen in the exhaust. In case if the exhaust emissions are too rich in fuel mixture (less oxygen) or too lean (less oxygen), then this sensor would generate a signal or voltage. The ECM uses the sensors voltage or alter the air fuel mixture ratio.
• Camshaft Position Sensor: The Camshaft postion sensor monitors the engine speed and pistion positions. The input signals received from this sensor is utilized to control fuel injection, ignition timing etc.
• Vehicle Speed Sensor: As the name suggests this sensor helps to identify the speed of the vehicle. In some cases this function is also does by the crankshaftsensor which control the ignition timing as well.
• Intake air temperature sensor:This sensor is mounted on the mounted on the air housing duct. This sensor detects the temperature of the air and according signals it to the ECM.
• Engine Coolant temperature sensor:The sensor is located on the housing of the radiator. CTS the ECM to identify the coolant temperature. If the temperature of the coolant is low (during mornings) then this would generate a signal to ECM. The ECM would enrich (increase fuel ratio) in the air fuel mixture.

During the initial start in the morning when the engine is cold the yopu might have notices the RPM of engine is quite high. Reason being the car runs on open loop. There are two types of loops open and closed loop. During the open loop, ECM signals injectors to injects extra rich air fuel (8:1)mixture to attain the optimum working temperature as early as possible. Maximum engine harm and emissions are produced during this phase.
Ones the engine attains its normal working temperature, ECM triggers back to close loop where the air fuel ratio comes back to nornal (14.7:1)

Atleast by now you might be able to get an idea of sensors loctaed in your vehicle.

The next parts contain information about the sensors of Maruti Zen and fault findings.

Code of the Sensors
http://img205.imageshack.us/img205/2...orcodesaw4.png

The link above reveals the names and the codes of the sensors in maruti zen.

How it works

http://img512.imageshack.us/img512/4...esystemqj9.png

The connector shown is the above link is located near the suspension hub of the co-driver side.Next to this connector, they will 2 relays for fuel pump and other is the main relay. PLEASE DO NOT GET CONFUSE. Using the ground wire bypass the terminals exactly shown in the figure. Ones the wire is bypass the mal function indicator (MAL) will flash. The MAL is nothing but the check engine light situated on the speedometer panel. The color of this light is ORANGE.
If the sensors are in perfect condition which is code 12. the SENSOR WILL BLINK ONES AND AFTER A HALT OF FEW SECONDS IT WILL BLINK AGAIN TWICE. This mean 12, normal code.

In case there is fault is TPS sensor, then the MAL will blink ones and then three times more, this means code 13, the TPS sensor is faulty.
Example
http://img265.imageshack.us/img265/9527/tpsqi2.png

Quite a few years back, when i performed this on my Zen, my hands were literally trembling at that time because i knew this could damage the whole ECM system as well. So please be carefull in case you decide to go ahead with this. Otherwise atleast you know its not that difficult to deal with problems of MPFI cars.



Thanks

[dinar]

hey can you let me know the price for the above mentioned sensors... and are they available outside [other than service center]....

[amitpunjani]

i am not really sure about the prices of each sensor individually. They are quite expensive.

[amitpunjani]

Hi there,

I have manage to get sesnor codes of all the Maruti cars. Will post them soon.
Thanks

Amit

[dinar]

just wanted to know if they where cheaper than getting sensors from abroad for my efi project.

[Magnan]

very informative.
May I know about setting of O2 sensor in Cielo ?

[amitpunjani]

Originally Posted by Magnan

very informative.
May I know about setting of O2 sensor in Cielo ?

HI

Not so sure about the O2 sensor for Cielo.

Amit

[alankarmotor]

HI, certainly very informative and good effort. But i would like to correct u on few points which are as follows: (1) about the ECM most of the information is correct exept that the ECM does recieve signals from various sensors but does not send signals back to the sensors but gives command to mainly ignition system and fuel system apart from A/C systems radiator fan and idle air control valve. (2) about the MAP sensor i would like to clarify that the only function of this sensor is to measure the load on the engine and not to measure temp. and humidity. (3) In the VSS (veh. speed sensor) column you have mentioned that crank position sensor allso can work as a VSS , which is incorrect.(4) TP sensor (throtle pos. sensor) is supposed to only inform the ECM about the angle of the butterfly valve position this is done by a potentio meter attached to the butterfly valve . Apart from these there other sensors allso in the sytem ,in fact u will be surprised even the brake pedal switch sends signal to the ECM. If you need further clarification on any systems of the MPFI system i can allways help.

Originally Posted by amitpunjani

Hi there

When Daewoo launched its first car Cielo, there was alot of hype about fixing the multi point injection cars. Alot of people infact including mechanic still have a notion that MPFI cars difficult to repair and the problem could not be rectified in authorised service stations.
Believe me its not difficult at all, atleast not for Maruti owners as maruti has system by which the faults of the sensors could be diagonised and rectified. Yes the owner will surely have to pay for the faulty sensor but will atleast end up saving the labour and VAT charges.

Here are list of few sensor which are deployed in Maruti Zen and there brief explanation of their function

• Engine Control Unit or Module- This is the brain of all the sensors. It is nornally located underneath the dashboard of the co-driver side.All the sensors sends the signals to the ECM which in turn sends the signals to the sensors for their functioning. The numbers 8 bit or 16 bit or 32 bit are associated with its capacity of ECM to performs the functions.
• Mainfold Absolute Pressure Sensor or MAP sensor- The MAP sensor introduced in mid 1980's, porvides information to the ECM (electronic control module) that accounts for the airflow's rate, temperature and humidity and airflow mass.
• Throttle Position Sensor or TPS- This located on the throttle body. It controls the amount fuel which is injected to the cylinders through the injectors.
• Oxygen Sensor or O2 Sensor or Lambda Sensor: This sensor is mounted on the runners of the exhaust mainfold. it is almost identical to a spark plug. The sensor controls the emissions of the vehicle, by sensing the amount of oxygen in the exhaust. In case if the exhaust emissions are too rich in fuel mixture (less oxygen) or too lean (less oxygen), then this sensor would generate a signal or voltage. The ECM uses the sensors voltage or alter the air fuel mixture ratio.
• Camshaft Position Sensor: The Camshaft postion sensor monitors the engine speed and pistion positions. The input signals received from this sensor is utilized to control fuel injection, ignition timing etc.
• Vehicle Speed Sensor: As the name suggests this sensor helps to identify the speed of the vehicle. In some cases this function is also does by the crankshaftsensor which control the ignition timing as well.
• Intake air temperature sensor:This sensor is mounted on the mounted on the air housing duct. This sensor detects the temperature of the air and according signals it to the ECM.
• Engine Coolant temperature sensor:The sensor is located on the housing of the radiator. CTS the ECM to identify the coolant temperature. If the temperature of the coolant is low (during mornings) then this would generate a signal to ECM. The ECM would enrich (increase fuel ratio) in the air fuel mixture.

During the initial start in the morning when the engine is cold the yopu might have notices the RPM of engine is quite high. Reason being the car runs on open loop. There are two types of loops open and closed loop. During the open loop, ECM signals injectors to injects extra rich air fuel (8:1)mixture to attain the optimum working temperature as early as possible. Maximum engine harm and emissions are produced during this phase.
Ones the engine attains its normal working temperature, ECM triggers back to close loop where the air fuel ratio comes back to nornal (14.7:1)

Atleast by now you might be able to get an idea of sensors loctaed in your vehicle.

The next parts contain information about the sensors of Maruti Zen and fault findings.

Code of the Sensors
http://img205.imageshack.us/img205/2...orcodesaw4.png

The link above reveals the names and the codes of the sensors in maruti zen.

How it works

http://img512.imageshack.us/img512/4...esystemqj9.png

The connector shown is the above link is located near the suspension hub of the co-driver side.Next to this connector, they will 2 relays for fuel pump and other is the main relay. PLEASE DO NOT GET CONFUSE. Using the ground wire bypass the terminals exactly shown in the figure. Ones the wire is bypass the mal function indicator (MAL) will flash. The MAL is nothing but the check engine light situated on the speedometer panel. The color of this light is ORANGE.
If the sensors are in perfect condition which is code 12. the SENSOR WILL BLINK ONES AND AFTER A HALT OF FEW SECONDS IT WILL BLINK AGAIN TWICE. This mean 12, normal code.

In case there is fault is TPS sensor, then the MAL will blink ones and then three times more, this means code 13, the TPS sensor is faulty.
Example
http://img265.imageshack.us/img265/9527/tpsqi2.png

Quite a few years back, when i performed this on my Zen, my hands were literally trembling at that time because i knew this could damage the whole ECM system as well. So please be carefull in case you decide to go ahead with this. Otherwise atleast you know its not that difficult to deal with problems of MPFI cars.



Thanks

[rohan_fonseca]

@alankarmotors: Could you please mention the other sensors and their functions.

[amitpunjani]

Originally Posted by alankarmotor

HI, certainly very informative and good effort. But i would like to correct u on few points which are as follows: (1) about the ECM most of the information is correct exept that the ECM does recieve signals from various sensors but does not send signals back to the sensors but gives command to mainly ignition system and fuel system apart from A/C systems radiator fan and idle air control valve. (2) about the MAP sensor i would like to clarify that the only function of this sensor is to measure the load on the engine and not to measure temp. and humidity. (3) In the VSS (veh. speed sensor) column you have mentioned that crank position sensor allso can work as a VSS , which is incorrect.(4) TP sensor (throtle pos. sensor) is supposed to only inform the ECM about the angle of the butterfly valve position this is done by a potentio meter attached to the butterfly valve . Apart from these there other sensors allso in the sytem ,in fact u will be surprised even the brake pedal switch sends signal to the ECM. If you need further clarification on any systems of the MPFI system i can allways help.

Hi alankarmotors

Thanks for correcting me. Yes i agree, the ECM sends signals to the acctuators and its the intake temperture sensor which measures the temperature.

Could you please elaborate how brake pedal switch send signals to the ECM? I hope we are not speaking about the cruise control as i just considering the Marruti Mpfi Zen into account.

Amit

[Magnan]

In Cielo Oxygen sensor is beside air filter box,under air fiter hosepipe. Correct ?. Can it be set manually as in Udaipur nobody has Analyser. If yes, please tell me how ?Twice I took my cielo to Ahmedabad but in vain. Any Cielo expert known to dear friends in near by area ?

[amitpunjani]

Originally Posted by Magnan

In Cielo Oxygen sensor is beside air filter box,under air fiter hosepipe. Correct ?. Can it be set manually as in Udaipur nobody has Analyser. If yes, please tell me how ?Twice I took my cielo to Ahmedabad but in vain. Any Cielo expert known to dear friends in near by area ?

Hi buddy

I have never seen under the bonnet of Cielo, but to my best of my knowledge O2 senswor is always located in the exhaust pipe. The one you are refering to might of MAP sensor or IAT sensor.

AMit

[dinar]

Originally Posted by Magnan

In Cielo Oxygen sensor is beside air filter box,under air fiter hosepipe. Correct ?. Can it be set manually as in Udaipur nobody has Analyser. If yes, please tell me how ?Twice I took my cielo to Ahmedabad but in vain. Any Cielo expert known to dear friends in near by area ?

If the sensor is in the air box,than it is air temperature senor as cielo had a MAF sensor near the throttle body [am I right?] the oxygen sensor is placed on the exhaust manifold. And one can only set it using a analyzer as the reading have to be seen before tuning.

[NetfreakBombay]

Originally Posted by alankarmotor

If you need further clarification on any systems
of the MPFI system i can allways help.

I have a 2008 model Alto LXi, does it report Engine RPM / Vehicle speed through OBD port ?

[Magnan]

Originally Posted by dinar

If the sensor is in the air box,than it is air temperature senor as cielo had a MAF sensor near the throttle body [am I right?] the oxygen sensor is placed on the exhaust manifold. And one can only set it using a analyzer as the reading have to be seen before tuning.

Yes.It must be correct.But I am still where I started.Without an Analyser I and will continue to suffer.