Help!!! Failed SMOG 2 times

[JohnU]

Does anybody know where I can get a diagram of just smog components for a 91 750il e32. I replace plugs and cleaned MAF but no go still failed.

The shop wants to trouble shoot it by process of elimination and im a cheap bastard.

Any help would be greatly appreciated

Thanks guys

[Torque]

Do you have the results of the test close to you? Post up what values your car tested with and what ranges they're looking for if you have them; that can tell a lot about what's wrong.

[JohnU]

Thanks here they are.

HC (PPM) 1400 rpm max 100 / I'M AT 187 = FAIL, 2000rpm max 74 / I'M AT 90 = FAIL,


CO(%) passed BARELY,


NO (PPM) 1400rpm max 741 / I'M AT 1518 = FAIL 2000 rpm max 680 / I'M AT 547= PASS

[Torque]

Sounds like it could be the cats and/or the oxygen sensors. I'd replace the O2 sensors at the minimum to start with and see where that takes it.

Bosch universal sensors are pretty cheap (though you have to actually do some work to get it wired to the original harness) ... original sensors with the harness are something like 80 bucks a piece

[marti5]

Sounds like the o2 sensors, if its got a rotten egg/sulphur smell from the tailpipe then its a cat...