1990 - 132000 miles. New air filter.
Pretty sure it's running rich, it blows black smoke when accelerating and leaves black deposits all over the bumper.
Haven't pulled the plugs yet, and I don't know when they were last changed so I will do that.
I was just wondering if anyone had any suggestions as to how I can fix this.
Thanks!

-Andrew

 

replace the o2 sensor.

 

cat?

 

Alright, i'll pick one up tomorrow.

The cat is not stock, neither is the muffler, but I assume since they are replacements that they are still functioning fine.

-Andrew

 

Old post^^^

But I put in a new 02 and there is almost no change in gas mileage or the deposits and black smoke during high rpms.

Any guesses?

 

don't look back, u wont see the smoke, problem solved lol

 

did you change your spark plugs already

 

I guess that would solve half of the problem...

No I haven't, but I was told they were relatively new. I guess thats next.

 

What is your setup? When you say new air filter, you didn't pull your AFM and put on a cone filter did you?

Don't laugh, a local guy did that to his Hyundai and couldn't figure out why it ran like hell.

 

Haha, no.
It's just a drop in K&N. I was just stating that it was replaced to rule it out as a problem.

 

^So your car is stock except for a K&N, cat, and muffler?

 

Thats correct.
The cat and muffler are just replacements from the previous owner. Nothing fancy.

 

Hmmmm.....
With a filter, and muffler being your only mod, I can't see how it could be rich if your o2 sensor is working properly. Those mods should make it run a little leaner if anything. Perhaps the cat is some cheap piece of **** and is already shot.

 

Thats a likely possibility...
But isn't the problem originating before both the catalytic converter and muffler?
If the cat really is crapped out would it cause the engine to run rich?
The o2 reading is before the cat anyways so wouldn't the problem be coming from a different source?

 

Check if you've got the oem injectors. Could be that a previous owner changed them. Or did it start when you changed the filter? Any warning lights? (shot cat --> limp home --> runs rich.)

 

No warning lights, seems the same as before the replacing the filter but I can't be 100% sure since I changed it right after I got it.
I just remembered the PO said the head had work done to it. Twice. The first time it was done crappily and the second was to fix the crappy job. I don't know if this would contribute to the problem.