E36 Replaced Knock Sensor Rough Idle

[dfsohio]

1993 325isI usually find all the answers I need here, but this problem has me worried and can’t find answers.The story from the beginning:I have been driving this car for six months, it runs decent but there has always been a strong exhaust smell (not sulpher or rotten egg).I was thinking it could be O2 sensor or catalytic converter. The fault codes showed both knock sensors. I read that knock sensor could cause the bad smell, possibly running rich.I replaced both sensors which took me all weekend. Now the engine starts, idles rough then stalls. Read fault codes again which showed “control unit supply” which I read happens when the battery has been disconnected. Cleared that code, started the engine several more times (still idles rough) but no other codes. So now I don’t know where to start, I’m thinking I failed to connect something.So my question is, has anyone had this happen after replacing knock sensors (both were cracked)? Any tips on where to start? I thought for sure there would be a fault code.Do the knock sensors need to be in a specific position?Additional info. I did not replace the six gaskets on the manifold. I did replace the throttle body gasket. I found a rotted vacuum hose from the throttle body to the valve cover. I did not have new vacuum line so I used fuel line that I had. I did not have a torque wrench for the sensors, so I guessed, the old ones were very tight.Thanks for any helpDfs

[rowen210]

Half way through reading your post I thought vacuum leaks. Then you said you didn't replace your manifold gaskets. Get it smoke tested. I usually get cat efficency lean codes with vacuum leaks. So... what kind of scanner are you using? Generic scanners can misread dealer specific codes.

[dfsohio]

I am using the Peake scanner. I ordered manifold gaskets, plan to remove the manifold and trace down a possible leak. I also plan to clean the MAF and ICV.

[jc43089]

Sounds like a vacuum leak now, the gaskets are reusable but not when they are 20 years old, also look at where the connections on the bottom of the manifold are.

[dfsohio]

Update: Replaced the manifold gaskets, cleaned MAF and ICV. Runs good, better than it did before. I am guessing it was the gaskets, that will teach me to be in a hurry. Also, the knock sensor codes are gone and I think the exhaust smell is gone.

[pbonsalb]

Also make sure the sensors are not cross connected. There are two sensors and two "banks" of cylinders that the ECU recognizes. If you plugged the sensor for bank 1 into the harness for bank 2 or if you put the bank 1 sensor in the bank 2 location (this would be for an obd2 car that has the siamesed harness), the knock control will try to correct but not be able to and the car will run poorly.