Should my car have a O2 sensor?

[M42Power]

Well, my is started showing signs of running rich lately; poor fuel mileage, high co levels and bad performance. I concluded that my o2 sensor was going bad so i went to check it out. It turns out that my car does not have an o2 sensor. The connector was plugged and i did not found the bung on the exhaust for it.

What is weird is that i remember that the car ran well and passed emissions with flying colors
should i install an o2 sensor?

Pics:





And just to make sure my diagnostic is right here is a pic of the sparkplugs

[jlevie]

A Euro car may not have an O2 sensor.

[KenC]

Do you have a catalytic converter?

[mikeedler]

never heard or seen of anything BMW after 1987 that didn't have a CAT here in Germany. Maybe someone just plugged it.
maybe your car was for an area that had really crappy fuel back then and BMW just saved alot of problems and did not use one????

My M3 is a non-cat car and also has the plug for a sensor, but nothing plugged in.

[M42Power]

The weird part is that it has a cat. The charcoal canister was also removed and the fuel tank vent line plugged. About fuel issues, my former 316i was older than my is and had all the stuff attached to it.

I am really clueless. Should i just retrofit an o2 sensor or just leave it and set the co level with the AFM set screw?

[mikeedler]

I wouldn't adjust or add an o2 sensor if it was running good before. I'd bet it's a vacuum leak causing the issues now. cracking hoses under the intake.

[M42Power]

I wouldn't adjust or add an o2 sensor if it was running good before. I'd bet it's a vacuum leak causing the issues now. cracking hoses under the intake.

I have had the mess under the intake fixed

[mikeedler]

To be honest, I hated my M42 I drove for a few months. It never ran correctly either- I didn't want to mess with it anymore, so I sold it to my apprentice at work to figure out.

[MikeDE]

Check to make sure the single connector plug(black wire), under the wiring cover, is connected. M42's that came out of the factory WITH a cat, should have it disconnected. If they came out of the factory WITHOUT a cat, it was connected and used another parameter to control idle emissions(don't remember what it was though, possibly intake air temp & engine speed).

Can't find a pic but it's by the front battery tray, you m42 guys know which one i'm talking about.....

EDIT-Found one




The M42 & M40 afm's are the same, throw in a known good M40 afm and see if that helps. The TPS is the same out of just about any M50. Cross-reference the part # on Realoem.com.