Hi,
I know there is a lot of topics about this subject, but in vain I've read many topics, I don't know what my problem is.
So, I have a '86 325i european model, and my old ECU is broken. it was a green label 153 ECU and I replaced it to a gray label 173 model, because I read they are compatible.
The car is running, but the ECU doesn't control the O2 sensor. The engine runs with poor mixture, and flashing the MIL (check engine) light. But there isn't any fault code in the ECU.
I downloaded all electrical drawings from the internet, and I read a lot of troubleshootings about the motronic, and I measured all signal, but I didn't find anything. Everything is ok. The O2 sensor is working, because when I manually moving the air flow sensors flap at running engine, the O2 sensor signal is changing. In fact I bought an oscilloscope for the fast signal, but nothing. And a few months ago I checked the exhaust emission with the old ECU, and then it worked fine.
Only one difference what I seeing beetwen the 1.1 and 1.3, there is a signal from the ABS to the pin 50. In my car this pin is empty, but this input has an 10kOhm pull down resistor, so it's voltage near to ground. (But I checked the injector cut off at engine brake, and it is working, the injectors switch off above 1500rpm, so I think this input doesn't missing for the ECU)
Has someone any idea, what should I measure yet or check?
Thanks.
I know there is a lot of topics about this subject, but in vain I've read many topics, I don't know what my problem is.
So, I have a '86 325i european model, and my old ECU is broken. it was a green label 153 ECU and I replaced it to a gray label 173 model, because I read they are compatible.
The car is running, but the ECU doesn't control the O2 sensor. The engine runs with poor mixture, and flashing the MIL (check engine) light. But there isn't any fault code in the ECU.
I downloaded all electrical drawings from the internet, and I read a lot of troubleshootings about the motronic, and I measured all signal, but I didn't find anything. Everything is ok. The O2 sensor is working, because when I manually moving the air flow sensors flap at running engine, the O2 sensor signal is changing. In fact I bought an oscilloscope for the fast signal, but nothing. And a few months ago I checked the exhaust emission with the old ECU, and then it worked fine.
Only one difference what I seeing beetwen the 1.1 and 1.3, there is a signal from the ABS to the pin 50. In my car this pin is empty, but this input has an 10kOhm pull down resistor, so it's voltage near to ground. (But I checked the injector cut off at engine brake, and it is working, the injectors switch off above 1500rpm, so I think this input doesn't missing for the ECU)
Has someone any idea, what should I measure yet or check?
Thanks.
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