cant pass smog.lots of soot in exh.pipe
 

1999 saturn SL2 heavy soot in exhaust pipe.
trouble passing smog.
Runs Great,other-wise.
only 96k miles !

Any one with any idea's ?

Please get someone to read the codes and list them. They will be in the Pxxxx format. We need more information about your car also like what kind of fuel mileage and why it won’t pass smog specifically.

If it was my car, I'd try cleaning the carbon out with water. It doesn't take much. Usually 2 to 4 ounces has worked fine for me. I just take the vacuum hose loose from my power brake booster and with the car at full operating temp, with it running, SLOWLY pour the water into the vacuum hose. YOU HAVE TO KEEP THE CAR RUNNING while pouring the water in. It will choke on you, so keep it running. It's not a race to dump the water all at once either. A very small stream is all you need. And if it tries to stall, stop pouring the water until you get it to recover. I have NEVER had to use a full 8 ounces of water in any car I've ever done this to.

Carbon & soot.Thinking about using sea foam spray.
my HC readings of 97@15 mph,47@25 mph. No Codes.
Idles smooth.
A local garage found this ---lambda readings indicate mixture is near perfect for catalyst function. CO/NO pass easily.
Took the car to a repair facility to have the AC recharged.
upon picking up the car,when I started it,it smoked so bad,the car was invisible.
Cleared up by the time I got back home,but noticed black soot in exh. pipe,and driveway.
New Cat has been installed,but just barely passes smog.
Have a chance to pick up a new Exhaust manifold cat.
If this cat is contaminated,won't it screw up my new downstream cat ?
Exh.manifold cat on line,does not ship to CA,where I live.
maybe not legal ?
Walker #16487

How much oil does it burn? Maybe the water temp sender for the computer is giving problems.

Why pay for Seafoam when water is free? It will do the same thing.

No code reading for faulty water temp sender.
No drivabilty problems.
Using CRC pass or dont pay additive,which is supposed to clean the entire fuel system.

Going to replace both O2 sensors,and install new exhaust cat converter.
Will keep you posted.

Only real connection between AC work and soot out the tail pipe based on your poststhey thunked some part of the exhaust or your EGR valve and knocked a clump of carbon buildup loose. I'm thinking EGR as the rest of the system is likely too hot. Thinking the EGR would end crap back through the cylinders to burn. Could have been the result of striking a curb, running over a speed bump to quickly, etc

Clean that throttle body. Wait, does that gen of s series have the whack pcv that is a slot into the block or am I thinking of the ion? Also, what color was the smoke? Blue is oil, black is fuel.

Did you have a hard time getting it to start at the AC shop? My s cars act out once a year and just don't want to start. PCM keeps dumping fuel but it's not firing. Once it does, I get a huge plume of black smoke as the charge of unburned fuel gets burned all at once. And it stinks rich

Seems the time the AC was recharged,SOMETHING they did started my high HC readings,and soot build-up in exhaust pipe.

The cat connected to exhaust pipe was replaced,to get the car to pass emissions (barely),but the cat that is integral with the exhaust manifold,I'm thinking must be plugged ?
Is there a way to clean out the soot in this cat ?.