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Discussion Starter #1
Hello. I need help. The barometric sensor shows over 1200 mBar. ECU Reset shows 1013 mBar and increases while driving. Is this normale? Is the barometric sensor in the ECU damaged? Other sensors replaced with new ones.
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I'm not aware of a barometric pressure sensor on the JTS. The point of a mass air flow sensor is that is not needed as it measures air mass rather than volume so that is automatically senses the air pressure without having to measure it.
 

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Discussion Starter #3
Information from Alfa Romeo Authorized Services. The atmospheric pressure sensor is located in the engine control unit. Maybe you know why I show 1200mBar and the weather shows 1020 hPa?What should I fix?
 

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Discussion Starter #5
I'm not aware of a barometric pressure sensor on the JTS. The point of a mass air flow sensor is that is not needed as it measures air mass rather than volume so that is automatically senses the air pressure without having to measure it.
In your opinion, the flow meter is responsible for measuring atmospheric pressure?
 

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It doesn't measure atmospheric pressure. It measures air mass which varies with volume, temperature and pressure. As the MAF incorporates an IAT (Inlet Air Temperature) sensor and by measuring air mass, the mass is more accurate than a volume measurement.

As you have a data stream for atmospheric pressure, I'd look for another sensor which largely mimics the AP value. It could be air mass, temperature or even look at fuel pressure etc.

What you haven't stated is how a fault manifests. Why are you looking into this and what is the engine doing or not doing?
 

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Discussion Starter #7 (Edited)
The car burns a lot about 20 liters. The airflow is 500-600 kg / h at high speed. I replaced the flow meter with BOSCH, MAGNETI MARELLI, PIERBURG. The only strange parameter is the atmospheric pressure, which is high and changes during acceleration. Then the car has a speed swing. This is my car. The barometric sensor is located in the ECM (example other Bosch F96).
I don't know if it is broken or if it shows such high volatile values. Maybe another JTS owner would have a say. MAGNETI MARELLI flow meter
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Judging from the fuel pressure in the first plot you were accelerating(?), and the barometric pressure was rising, but only by 15mBar. It is probably just the ram effect raising the pressure in the engine bay. Try plotting vehicle speed and barro pressure, see if they correlate.


I don’t know why you got a reading of 1200mBar, what were the conditions? Does it change to the correct value when you start the engine? I would not assume you have a fault yet.
 

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Yes, baro sensor is typically inside ecu. It could be damaged. Baro is used for ecu to change engine management like injection strategy, so it can affect performance. If you real baro pressure is near 1000 mbar then 1200 from faulty ecu is not a real issue because ecu parameters usually are the same from 980 to up. If you real baro is under 980 mbar engine will work with fake perfect conditions (1200 mbar) and you could feel some performance issues.
 

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Discussion Starter #11
Judging from the fuel pressure in the first plot you were accelerating(?), and the barometric pressure was rising, but only by 15mBar. It is probably just the ram effect raising the pressure in the engine bay. Try plotting vehicle speed and barro pressure, see if they correlate.


I don’t know why you got a reading of 1200mBar, what were the conditions? Does it change to the correct value when you start the engine? I would not assume you have a fault yet.
Conditions were normal, I live 319 m a.s.l. 1022 hPa. I move on a flat road. 15 mBar / 15 hPa is a height of 125 meters. I have no mistakes. When the ECU is reset, the sensor shows 1013mBar and increases with the distance traveled and gas added while driving. When the car stands on the parking lot and adds a lot of gas, the parameters of the sensor do not change only during acceleration. After starting the engine, there is a high parameter. The new char
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Discussion Starter #12
Yes, baro sensor is typically inside ecu. It could be damaged. Baro is used for ecu to change engine management like injection strategy, so it can affect performance. If you real baro pressure is near 1000 mbar then 1200 from faulty ecu is not a real issue because ecu parameters usually are the same from 980 to up. If you real baro is under 980 mbar engine will work with fake perfect conditions (1200 mbar) and you could feel some performance issues.
In your opinion, the sensor in the central unit is damaged, and it shows such swings. Can it show a high false airflow? High fuel consumption. My pressure in the area is 1022hPa. Such a sensor should show the actual pressure in the area? Truth?
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In your opinion, the sensor in the central unit is damaged, and it shows such swings. Can it show a high false airflow? High fuel consumption. My pressure in the area is 1022hPa. Such a sensor should show the actual pressure in the area? Truth?
If your real pressure is 1022 and ecu shows 1211 it's has some issue for sure. Ecu sensor is not perfect, always have some error, but no 200 mbar. My JTD show +-20 mbar with regard to real.

About airflow it's different sensor, it's in MAF, but can be affected by damaged baro sensor or some other ecu issue. Anyway your airflow looks like normal for 2.0 atmosferic engine, you can check logs from other JTS engines.
 

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interesting picture of the Bosch ECU surrounded by sensors and all the other parts, where does this come from ?
 

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I was hoping that 1200mBar was some sort of ‘full scale’ test mode, but you have 1107 as well so yes it must be a fault. Very strange fault though, why does the error in your first graph appear to be proportional to speed??


Does tapping the ecu change the reading?


ps: I tried mine (a 156 jtdm), there was no ram effect up to 70mph.
 

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Discussion Starter #17
If your real pressure is 1022 and ecu shows 1211 it's has some issue for sure. Ecu sensor is not perfect, always have some error, but no 200 mbar. My JTD show +-20 mbar with regard to real.

About airflow it's different sensor, it's in MAF, but can be affected by damaged baro sensor or some other ecu issue. Anyway your airflow looks like normal for 2.0 atmosferic engine, you can check logs from other JTS engines.
I checked on the Polish forum. I thought 480 kg / h is the maximum.
 
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