On Nov 11, 2003, at 15:46, Joswick, Chris wrote:
so CO and HC slightly better and NO worse, any thoughts anyone? i figure that could just be normal variation thanks all
Given that all the numbers are above limits, how old is the cat? It doesn't seem like it's working.
I assume you've done all the normal tune-up stuff like plugs, air filter, etc. You should also confirm that the fuel mixture is in spec and all the various vacuum lines and fuel injection stuff is in place. Still, I think you're looking at needing a new cat- those numbers are so high, something is clearly wrong. A properly tuned engine should be *far* lower than what you are getting. Another overlooked important point: be sure the car is fully warmed up before the test; incidentally, a failed coolant temp. sensor can force the engine to run in its cold enrichment mode even when it's warm. Even after all that, the quickest solution is probably just to replace the cat if it's old. For reference, I just had my '91 Protege tested here in Connecticut- the limits here are much stricter and I had no trouble passing with a catalytic converter that is of unknown age:
Limit/actual HC: 167/142 CO: 1.11/0.17 NO: 1944/865 Good luck, Chris
