MAP sensor problem

[Sharo53]

guys I want to know that...all the MAP sensors in the world operates on 12volts or they are different??

I checked my sensor and didn't find 12 volts any where.......is their a problem in wiring??
while driving car suddenly starts de-accelerating like we take off the foot completely...and it ignores to accelerate even the accelerator is floored...
then suddenly it comes back to life....with "check engine" light ON
this all happens in 4-6 seconds sometime just in 2 seconds...

today I drive the car with MAP sensor disconnected...and it doesn't behaves like this...just the accelerating response was low

car in discussion is Chevrolet joy

[Sohaib93]

You can test the MAP sensor using the voltage fluctuating test.
Connect a voltmeter at appropriate terminals and increase the throttle.The voltage output should increase with increasing throttle.
Another test is to simply unplug the sensor while the car is running at idle and see if the engine runs better.If it does , the sensor is bad.
Or use a scanning tool to read error log form the ecu.
Or check the resistances of the sensor wires according to your cars specified values.

[raohamid]

It is very possible that your MAP sensor is bust. However, understand that sensors are usually very durable and if they do fail, its seldom out of wear and tear, its because of issues that are not directly related to the sensor.

If I were you, I would get the CEL codes checked first, that will isolate what type of issue you have. Then, I'm betting the problem is electronics or fuel pump/injector related, and probably not directly related to your MAP sensor.

Also note, if a MAP sensor goes bust, trust me you will know. More probably, you will see plumes and plumes of smoke from your exhaust and horrible idling also.

Just my 2 cents.

Rao.

[SER_GTR]

Check For The Output Voltage To ECU Which Varies As Change In Mani Pressure Occur

[dms664]

get an OBD scan first to know the error code first and then proceed according to that error code.

[Sharo53]

You can test the MAP sensor using the voltage fluctuating test.
Connect a voltmeter at appropriate terminals and increase the throttle.The voltage output should increase with increasing throttle.
Another test is to simply unplug the sensor while the car is running at idle and see if the engine runs better.If it does , the sensor is bad.
Or use a scanning tool to read error log form the ecu.
Or check the resistances of the sensor wires according to your cars specified values.

will check the voltage again..

engine's rmp remain stable whether the sensor is connected or not..

where should i find Chevrolet JOY's factory repair manual..its not available on net

It is very possible that your MAP sensor is bust. However, understand that sensors are usually very durable and if they do fail, its seldom out of wear and tear, its because of issues that are not directly related to the sensor.

If I were you, I would get the CEL codes checked first, that will isolate what type of issue you have. Then, I'm betting the problem is electronics or fuel pump/injector related, and probably not directly related to your MAP sensor.

Also note, if a MAP sensor goes bust, trust me you will know. More probably, you will see plumes and plumes of smoke from your exhaust and horrible idling also.

Just my 2 cents.

Rao.

sir the main problem is its is not giving error code every time... like if we checked the codes with scan tool it shows map sensor code and after clearing the codes and restarting the car it didnt show any code....
if it show the code every time i check it then its obvious that i had to change the sensor but why it didnt show the code every time?

when i disconnect the map sensor's wire and drive the car i didnt see any smoke form the exhaust.

Check For The Output Voltage To ECU Which Varies As Change In Mani Pressure Occur

i checked that...it was changing with the load ON and load OFF....this measn my sensor isnt damaged..?

get an OBD scan first to know the error code first and then proceed according to that error code.

[Sharo53]

bump..

[Xulfiqar]

not all sensors work are 12V linear sensors, e.g. the japanese sensors usually are 5V reference sensors.

As your car is electric throttle I would suggest you check the fault codes and repair from there. It seems that the motor is lazy or sticking.

btw, your coolant expansion tank is very dirty, what coolant are you using in it?

[Sohaib93]

Did you check voltage between V-out and Ground terminal ?

[asif_ak3]

Salam All!

I also own a Joy 2006. On CNG.
When I run it on Petrol, the Car fuel consumption is excessive. around 50 KM to 5 litres without AC and passive drive, The car knocks at times, Engine rough idles at times and there is missing at times. Also the response is erratic at times, like at times the car is struggling to gain power.
On CNG, 40KG cylinder, AVG is 70 KM without AC. Missing is not there but at times seems like car is loosing power, and the pedal response is also erratic, like car not revving on pressing accelerator.

Also the CHECK ENG light is always on (CNG+Petrol). some times it (RARELY) goes away.

I live in Karachi. Your expert opinions will be much appreciated.

regards

--Asif--

[Sharo53]

not all sensors work are 12V linear sensors, e.g. the japanese sensors usually are 5V reference sensors.

As your car is electric throttle I would suggest you check the fault codes and repair from there. It seems that the motor is lazy or sticking.

btw, your coolant expansion tank is very dirty, what coolant are you using in it?

sorry, i totally forgot this thread...

yes it has electric throttle and no idle valve.
on first check for error codes it gives code for MAP sensor, then we clear all the codes and drive the car for about 2Kms and checked again, and no codes were found...
did the same again and on 3rd check again code for MAP.......what is this..i mean if MAP sensor is faulty that code should come every time?
for now im living with this problem.

about coolant i was using some crapy coolant that time..now replaced with pyro coolant

[Sharo53]

Salam All!

I also own a Joy 2006. On CNG.
When I run it on Petrol, the Car fuel consumption is excessive. around 50 KM to 5 litres without AC and passive drive, The car knocks at times, Engine rough idles at times and there is missing at times. Also the response is erratic at times, like at times the car is struggling to gain power.
On CNG, 40KG cylinder, AVG is 70 KM without AC. Missing is not there but at times seems like car is loosing power, and the pedal response is also erratic, like car not revving on pressing accelerator.

Also the CHECK ENG light is always on (CNG+Petrol). some times it (RARELY) goes away.

I live in Karachi. Your expert opinions will be much appreciated.

regards

--Asif--

brother the easiest way is to take your car to Chevrolet dealer and get it scanned through computer...

btw whats the reading on odo meter?

[asif_ak3]

Odo is 60,000. I did go to Chevy dealer in Karachi, and he just did cleaning, little tuning and said the light is on becuase of FF CNG. hmmm but I still have my doubts. Car is however Much smoother to run on CNG than petrol.
I will go again maybe this week...I have a feeling there is some issue with Fuel delivery. Fuel filter/pump/injector, because I do 50/50 run on CNG/petrol in a week. What say?

[Sharo53]

i think the problem is with the wiring of injectors...ask him to remove the wiring of emulator from injectors and connect them directly with ecu wiring (just for check purpose) i hope you will find the problem...