HC ppm on a pontiac

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cherger - 26 May 2006 21:54 GMT

I went and had an emissions done on my 1990 Grand am. i have replaced the
oxygen sensor, timing chain, fuel injectors, manifold, crankshaft sensor,
engine module, fuel filter, alternator belt and a few more things. The only
thing I haven't changed was the catalyric converter. I put a new muffler and
pipe on it 3 years ago. but never chnged the catalytic converter as the guy
said I didn't need one. everything passed except the HC ppm the reading was
207 allowed is 174. I noticed when the guy got in and revved the motor black
smoke can out of the pipe for a minute and then stopped. Could this be the
converter? Also I changed the EGR valve yesterday. Also when the car starts
first thing in the morning it stumbles. Could my converter be clogged up?

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Shep - 26 May 2006 23:21 GMT

High HC's is usually raw fuel unburned in the exhaust, misfire, rich mixture
are some issues. A full scan and diagnosis for the rich condition is
required.

>I went and had an emissions done on my 1990 Grand am. i have replaced the
> oxygen sensor, timing chain, fuel injectors, manifold, crankshaft sensor,
[quoted text clipped - 12 lines]
> starts
> first thing in the morning it stumbles. Could my converter be clogged up?

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