instructor74

here is what i am thinking what do you guys think. 93 si with 203k on it uses about 1/2 qrt oil every 3k.(not to bad). In the last few months I have started to notice when vtec kicks in there is a slight bog then a large puff of black smoke out the tailpipe. then the car is fine everything runs great. this will repeat every so often. The car is well tuned all new electrical msd.I think it might be the cat is clogged it is still the original.

Suck my DX

whats the question ?
if your concerned about the cat being clogged, take it out and have a look

philosofy1

the black smoke is not bad. for the cat, just replace it for a high flow one. it's time to replace it anyway.

cambopheonix56

The black smoke is from running a little rich. Replace your cat, see what that does.

instructor74

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cambopheonix56 &raquo;</TD></TR><TR><TD CLASS="quote">The black smoke is from running a little rich. Replace your cat, see what that does.</TD></TR></TABLE>
I know that black smoke is from running rich. the problem is the engine falling on its face then belting out the black smoke and coming to life. Ive had this car since new and never have had this problem before. I was just looking for thoughts on what it might be. I was starting to suspect the cat was the cause of the problem.