Black deposits on the muffler tips

[romerodec]

Hi guys...

This forum is pretty neat!... I´m connecting from Venezuela, and I own a 2001 Pontiac Sunfire GT (2.4 L engine - don´t remember the VIN code).

I modifyied the exhaust system, and removed CAT converter and stock mufflers... I installed two low restriction Powertech exhaust mufflers... The car sounds really good, but when you turn it on it blows a lot of black smoke through the exhaust tips (only for 1 or 2 secs) and the exhaust tips are always collecting a lot of dark, fine black powder (charcoal?)...

The spark plugs are OK, air filter OK (hope to change it very soon for a cold air intake system -AEM?) and ECU parameters are also OK... Have you got any clue on how to fix this?

Thanks a lot!

[GTP Dad]

This sounds like a rich condition in the fuel system. The O2 sensor may be bad and causing the engine to get too much fuel. These can start to go bad and not give a check engine light.

[romerodec]

Ok... And does that O2 sensor malfunction could also explain the black smoke when starting the engine?

It is really hard to get a O2 sensor here, but which one would you say is responsible, the one placed directly after the exhaust manifold or the one after the CAT converter?

[GTP Dad]

I would say the one after the cat. It is looking for a certain level of O2 and since you removed the cat it is giving the computer a bad reading. You may want to replace it with an O2 similator that is available from several places. Try pfyc.com they should have one. The similator will give the correct readings to the computer all the time and therefore should eliminate the problem.