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Title: Bosch MED9.1 MAP issues Post by: simonas88 on December 22, 2018, 09:50:27 AM Hello,
I have an issue with Bosch MED9.1 ecu from a mk6 golf R. VCDS reports a fault with MAP (signal too low), measuring blocks show 0 mbar absolute pressure. The sensor has been replaced already, so it should be okay. The wiring loom should also be okay, because I checked the circuit between the ecu and sensor connectors. I think the problem lies in the ecu. With ignition on I measured the voltages at the sensor connector. It returned 6V at the outer wires (ground and green/purple), also the voltage was steadily rising while I carried out the measurement (1/100th of a volt every few seconds). Voltage between the ground and black wire (signal?) measured at 1.1V. Then I connected the sensor and continued the measurements directly on the ecu motherboard. As soon as I connected the sensor, the voltage between the outer wires (ground and power supply) dropped to about 0.4V. Ground and signal remained the same. A bit of back story: it's a crashed car; the wiring loom was damaged. The wires that were snapped belonged to the map sensor. While I carefully repaired the loom, there was a burned track on the ecu circuit board where the ground pin is located (which I managed to repair). I think during the crash some 12V wire shorted with the map sensor wires down from the ecu. Any ideas how I could make sure that the ecu is or isn't repairable? Also, how do I completely remove the motherboard from the casing? It seems glued, so I'm not sure about just ripping it out by force... Title: Re: Bosch MED9.1 MAP issues Post by: gman86 on December 22, 2018, 06:12:43 PM Hello, I have an issue with Bosch MED9.1 ecu from a mk6 golf R. VCDS reports a fault with MAP (signal too low), measuring blocks show 0 mbar absolute pressure. The sensor has been replaced already, so it should be okay. The wiring loom should also be okay, because I checked the circuit between the ecu and sensor connectors. I think the problem lies in the ecu. With ignition on I measured the voltages at the sensor connector. It returned 6V at the outer wires (ground and green/purple), also the voltage was steadily rising while I carried out the measurement (1/100th of a volt every few seconds). Voltage between the ground and black wire (signal?) measured at 1.1V. Then I connected the sensor and continued the measurements directly on the ecu motherboard. As soon as I connected the sensor, the voltage between the outer wires (ground and power supply) dropped to about 0.4V. Ground and signal remained the same. A bit of back story: it's a crashed car; the wiring loom was damaged. The wires that were snapped belonged to the map sensor. While I carefully repaired the loom, there was a burned track on the ecu circuit board where the ground pin is located (which I managed to repair). I think during the crash some 12V wire shorted with the map sensor wires down from the ecu. Any ideas how I could make sure that the ecu is or isn't repairable? Also, how do I completely remove the motherboard from the casing? It seems glued, so I'm not sure about just ripping it out by force... Hook up VCDS with the ECU on the bench. The MAP sensor open circuit should read 3220mbar. If it still reads 0mbar, something's dead. Make sure software is stock too. Title: Re: Bosch MED9.1 MAP issues Post by: simonas88 on December 24, 2018, 01:45:29 AM Hook up VCDS with the ECU on the bench. The MAP sensor open circuit should read 3220mbar. If it still reads 0mbar, something's dead. Make sure software is stock too. I don't have a bench, but when the ecu is plugged into the car with ignition on and the sensor removed, VCDS reads 3220mbar exactly. What could this mean? Title: Re: Bosch MED9.1 MAP issues Post by: _nameless on December 24, 2018, 02:25:34 AM Wire 5v and signal to ecu wrong or your map sensor is cooked bub
Title: Re: Bosch MED9.1 MAP issues Post by: simonas88 on December 28, 2018, 01:14:03 AM .
Wire 5v and signal to ecu wrong or your map sensor is cooked bub ECU is stock, MAP sensor is good (new, correct P/N), wiring from ecu connector to the MAP connector is checked and double checked. I'm guessing my ECU is toast :( On a related note, is it true that I could BDM clone my original ECU software (including IMMO) onto whichever Bosch MED9.1? I've found a cheapo ecu from B7 A4 2.0 tfsi. Title: Re: Bosch MED9.1 MAP issues Post by: gman86 on January 02, 2019, 12:56:55 AM . ECU is stock, MAP sensor is good (new, correct P/N), wiring from ecu connector to the MAP connector is checked and double checked. I'm guessing my ECU is toast :( On a related note, is it true that I could BDM clone my original ECU software (including IMMO) onto whichever Bosch MED9.1? I've found a cheapo ecu from B7 A4 2.0 tfsi. Yes Title: Re: Bosch MED9.1 MAP issues Post by: simonas88 on January 29, 2019, 11:07:07 PM In case anyone wonders in the future, I swapped a BDM-cloned ECU (from a Passat) and the issue was resolved.
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