Failed smog tests, can't seem to fix

[Jim Con]

Also posted on E24 forum.

My 86 635, 99,000 miles has been failing smog tests on being too rich.Car idles badly too high and erratic.
I have checked all the usual suspects, discoed cold start valve, have swapped AFM for known good one, CTS, ICV, on and on.

Can get it to run if I pull and clean plugs and let it air out.
One mechanic said drippy fuel injectors ( changed ), another said new 3.0 fuel pressure was running at 2.5 bar, changed back to original Bosch 3.0, still way rich.

I'm stuck on this one, all 6 plugs ( correct ) are equally black and wet ,shouldn't be injectors.

Any ideas?
I'll remember you in my will!

Jim

[PostChris909]

Also posted on E24 forum.

My 86 635, 99,000 miles has been failing smog tests on being too rich.Car idles badly too high and erratic.
I have checked all the usual suspects, discoed cold start valve, have swapped AFM for known good one, CTS, ICV, on and on.

Can get it to run if I pull and clean plugs and let it air out.
One mechanic said drippy fuel injectors ( changed ), another said new 3.0 fuel pressure was running at 2.5 bar, changed back to original Bosch 3.0, still way rich.

I'm stuck on this one, all 6 plugs ( correct ) are equally black and wet ,shouldn't be injectors.

Any ideas?
I'll remember you in my will!

Jim

A simple air leak could easily cause a rich/lean condition. I had a similar problem, changed injectors, plugs, even MAF sensor and intake boots. Turns out my throttle body gasket was trash and long gone along with a my intake manifold gasket. Could have been either or, but after replacing both and cleaning my ICV, it got rid of the issue. Even took my mpg from 8 to 20. (This all was the case for my E39 528i of course)

Sent from my SM-G955U using Tapatalk

[trackerrrr]

Agree with PostChris909. Check for vacuum leak(s) between MAF and cylinder head.

Also is air filter clean?

[demetk]

Connect a multimeter onto the O2 sensor output signal and see what the voltage is when the engine is idling.

[jehu]

If an engine say like an M 60 consumes oil is it likely not possible to ever pass An emissions inspection such as in New Mexico?