O2 sensors proper connection

[bentibo1974]

Hey guys, my first post on the forum. I just bought an 850i 1991 and having problems with low load acceleration. The car is just choking and smell gaz big time. I'm suspecting that the previous owner inverted the O2 sensors connections (right sensor with left side and vice versa). So would someone have a picture of the O2 sensors with their proper connection underneath the car. Thanks for your help guys. Much apreciated.

[IcemanBHE]

Welcome to the forum.

[shogun]

I only have a pic of the E32 750 1992 M70 connectors, right side goes to right side which is a bit more in front, left to left connector
http://infinitier.ddo.jp/e32/page/ma...inte_50707.htm
Or you just swop them under the car and see how the engine runs. I mixed that once up and immy could notice from the engine running, very rough idle.

Or disconnent one side and test with a multimeter on the Motronic, for the 352 the pins are Lambda on pin 70, and Lambda ground on pin 71.
Remove the cover plate from the Motronic connector and then connect the connector again, then start the engine and test with a multimeter and it should move within 1 second between 0.1-0.9 volts, the faster the better.
Here pics for better understanding
http://img293.imageshack.us/img293/5...onik005tm0.jpg
http://img167.imageshack.us/img167/2...onik001zi7.jpg
The one not connected should then show no volts, so you know which one is connected to which Motronic.
I hope I could explain that understabable with my poor English.

[bentibo1974]

Thanks !

I only have a pic of the E32 750 1992 M70 connectors, right side goes to right side which is a bit more in front, left to left connector
http://infinitier.ddo.jp/e32/page/ma...inte_50707.htm
Or you just swop them under the car and see how the engine runs. I mixed that once up and immy could notice from the engine running, very rough idle.

Or disconnent one side and test with a multimeter on the Motronic, for the 352 the pins are Lambda on pin 70, and Lambda ground on pin 71.
Remove the cover plate from the Motronic connector and then connect the connector again, then start the engine and test with a multimeter and it should move within 1 second between 0.1-0.9 volts, the faster the better.
Here pics for better understanding
http://img293.imageshack.us/img293/5...onik005tm0.jpg
http://img167.imageshack.us/img167/2...onik001zi7.jpg
The one not connected should then show no volts, so you know which one is connected to which Motronic.
I hope I could explain that understabable with my poor English.

[bentibo1974]

Thanks Shogun. I will try this PM and let you know!

[Wuffer]

So if you suspect that someone inverted the O2 sensor connectors, take 10 minutes, crawl under the car, switch the two connectors and test. They are either connected correctly or they are inverted. The only other options are they (or one) is not connected, there are broken wires or they (or one) is dead.

[bentibo1974]

Thanks a lot guys for your prompt reply. I just swapped the connector and the car works great now !!!!! I'm an happy man Special thanks to Shogun oncw again.

[shogun]

Thanks for the feedback. That even happens to us experienced guys sometimes when in a hurry.
Therefore I can only recommend to all, to mark the connectors coming from the engine room with 1 and 2 or left and right bank/exhaust when changing oxy sensors before disconnecting the oxy sensors.
Anyway, if wrong connected, that can be felt immy when engine is started by the poor running of the engine.

[Rlequerica]

Thanks for the feedback. That even happens to us experienced guys sometimes when in a hurry.
Therefore I can only recommend to all, to mark the connectors coming from the engine room with 1 and 2 or left and right bank/exhaust when changing oxy sensors before disconnecting the oxy sensors.
Anyway, if wrong connected, that can be felt immy when engine is started by the poor running of the engine.

Hello Shogun:
I have the same problem with my 2009 E90 328i sedan N52. Valvetronic and non turbo.
I removed the connectors from the fuel rail...so I really dont know which one was in the front and rear side of the rail..

Please help me out.
Rod