And before anyone says anything, yes I searched. I got a lot of un-educated posts. Nothing that helped me.

Anyhoot.......

This is on a 1990 535i/5. I just bought it. Sight unseen. Had it running in driving withing an hour. I replaced the clutch slave cylinder, and the intake hose.

Symtoms: dark gray smoke. little bit of a sputter, but sputter goes away at full throttle and at high RPMs. When it sputters, the check engine light comes on. I got a code 1222. Also, strong smell of gas, and REALLY REALLY bad gas mileage.

At full throttle, it runs perfect, and the check engine light goes out. BUT, it still smokes.

I have a feeling it's either the O2 Sensor or something to do with the cats.

What symptoms are there when your cats get clogged? I was told that you should loose power at higher RPMS.

I plan on starting with plugs, cap, and rotor, first. This car sat for a really long time before I got it. I also put injector cleaner and fresh gas in it, but was only able to drive it about 15 miles afterwards.

And before anyone says anything, yes I searched. I got a lot of un-educated posts. Nothing that helped me.

Anyhoot.......

This is on a 1990 535i/5. I just bought it. Sight unseen. Had it running in driving withing an hour. I replaced the clutch slave cylinder, and the intake hose.

Symtoms: dark gray smoke. little bit of a sputter, but sputter goes away at full throttle and at high RPMs. When it sputters, the check engine light comes on. I got a code 1222. Also, strong smell of gas, and REALLY REALLY bad gas mileage.

At full throttle, it runs perfect, and the check engine light goes out. BUT, it still smokes.

I have a feeling it's either the O2 Sensor or something to do with the cats.

What symptoms are there when your cats get clogged? I was told that you should loose power at higher RPMS.

I plan on starting with plugs, cap, and rotor, first. This car sat for a really long time before I got it. I also put injector cleaner and fresh gas in it, but was only able to drive it about 15 miles afterwards.

I have similar issues.. At first I was getting the 1222 code.. now I'm getting the 1215 code.

Mine started when I replaced the AFM with a MAF. I ended up checking the Throttle Position switch..and had to adjust it. It ran fine for a few months. Now of course it's the 1215 code.

It might be the O2 sensor, but replacing the plugs, cap, rotor are a good start first... and a valve adjustment. Other things that might be culprits are vacuum leak, Fuel Pressure Regulator, fuel filter, fuel pump, throttle position switch, and coils.

I plan on doing the same one of these days. Luckily, I only see the CEL and stutter every few weeks. I just rev up the engine and CEL clears and runs fine for a few weeks. Although I plan on cleaning my MAF also since it's been known to get dirty.

Keep us updated.

Loose airflow meter spring.
Bad engine coolant temperature sensor.
Leaky injectors.