Ok here's the story...

I own a 1990 RS 305 TBI automatic with 237,700mi on the original engine. I pass all of the safety and high speed emissions but I fail the low speed HC and CO/CO2 emissions. I've changed the distributor, plugs, wires, cleaned out the intake, running 93 octane gas, and it has fresh oil in it--so does anyone know WHY I'm failing and HOW to fix it? I do have some blow-by (bad ring(s) or valve seal(s) hah or both) but the car has passed emissions with this problem for 90k-100k miles already. I'm at a loss on how to fix the problem without resorting to a rebuild or new engine. I don't have the cash yet for a new engine. If needed I can provide the exact numbers of my 2 emissions tests.

Any help is greatly appreciated.

 

Maybe a new cat and or muffler? How are the emmission lawsGermany?

 

A new cat, new plugs, O2 sensor,& heavier grade oil to cut down onoil burningmay help. Also make sure there are no leaks in the exhaust system, or it won't pass the CO2 test.

 

The cat is less than 4 years old. I've been putting in 10w30 oil, should I use 10w40 or something a little thicker? Also there is one tiny leak in the exhaust after the muffler. Is the O2 sensor inside the air intake housing or is it locate somewhere else? I'm not that familiar with the 305/350 engine. Thanks for the help too by the way.

I actually live in Texas, I'm just from Germany.

 

Cat and egr

 

Has any one noticed that new GM and others have thier parts manufactured in China? I was told it was China, Texas. Is that any where near Germany, Texas

 

I wish there was a town in Texas called Germany--I might move there. I'm going to get a new cat installed tomorrow--a local shop has them for about $50 and its $50 for the installation. That and I'm going to try and replace the EGR valve tomorrow...isn't that near the distributor cap on the firewall?

 

The cat is not that old. Hold off on it. The egr is on the right , rear of the intake manifold. Near the distributer. The O2 is in the exhaust manifold on the left side near the #5 plug

 

Do you know of a guide with pics for replacing the EGR valve? I haven't replaced one of those yet so my experience is limited--actually its zero. lol

I've replaced the PCV valve and put a breather inplace of the rubber tube from the valve covers to the intake pan. I can't believe how stupid Chevy is for the way this engine is setup...or is it the fault of the US Goverment for the emissions bullsh*t? From the smog pump to the idiotic way the air intake is setup...its just mindblowingly redundant.