Here's my situation (for those who want it). I own a '90 RS 305 TBI that has as of right now 237,812 original miles on the engine/chassis and I'm trying to get my emissions to pass to get a current inspection.

My first attempt was doing absolutely nothing to improve any reading--I ran it as-is. I pass the safety (I worked at the place so I'll always pass the safety lol) and the high speed emissions (25mph).

3/27/2007 emission test results
High Speed (25mph) -- Low Speed (15mph)
Readings: reading need to pass/my reading [if failed will use red] [if pass will use green]
HC 148/147 -- 152/250
CO 0.94/0.51 -- 0.86/2.73
NOx 1047/488 -- 1146/730

Next test after I do the following; replace distributor cap, plus wires, plugs, intake cleaner through the vaccuum line, premium fuel, and clean up the air breather and all intake tubes around the throttle body.

4/04/2007 emission test results
High Speed (25mph) -- Low Speed (15mph)
Readings: reading need to pass/my reading [if failed will use red] [if pass will use green]
HC 148/134 -- 152/242
CO 0.94/0.10 -- 0.86/1.53
NOx 1047/497 -- 1146/594

So as you can see I still need work to pass the HC and CO. Any suggestions? I know that replacing the EGR valve will most likely effect NOx and not HC or CO. CO tells me that maybe there is an exhaust leak of some kind? I'm not real knowledgable in this area so I need some assistance.

 

9 days later and no one has any ideas?

 

Von Kaiser


It is probably your CAT - if it is original have it R&R. HC is high for both speeds. Did you get remainning oxygen percentage as well?
EGR begins to operate at higher road speeds - (got to check for that)

//RF

 

Sea Foam, I was running about the same Numbers on the 2nd test you have. I ran Seafoam through the carb and vac lines.. (1983 Camaro Berlinetta 305) I also had the original cat. But Try running some Sea Foam through the engine. Give it a Good dose, and you'll prob. pass.. If you dont know what sea foam is or where to get it, Its a Advance Auto and VIP. And prob. Napa.. Look around at the local Parts stores.. 240,000 Miles, Man, I can only imagine the carbon build up on the valves.. Get some sea foam, and let us/me know how you made out!
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Oh, BTW, You dont want to run the sea foam During the test! Some where out of the city/town your gonna wanna be away from civilization.. Because the Petrolium (Seafoam) Breaks up the carbon and turns it into a gas.. Blue Smoke... and the more miles on the motor the more its gonna smoke, because theres so much carbon in the motor/Cat.

 

was it fully warmed up?
make sure the AIR injection isn't putting air to the exhaust manifolds after its warmed up.
a weak cat is a possibility.
make sure your O2 sensor is good, if its more than 2~3 years old its probably getting sluggish.

not knowing what the cat is doing, it looks like its running a little rich on the low speed test.
if you can, try running a training mode test & then without turning the motor off run it a second time & see what readings you get.

 

The CAT is about 3.5 years old. Can a CAT go bad in such a short amount of time? I only got a print out of the stuff that I typed up in my first post. Is it a per-shop thing to give the remaining oxygen %? I didn't think the EGR would effect the HC and CO portion of my test. I'd rather not have to replace te EGR since the part alone costs $77 at O'Reilly's and Autozone. Need to do the cheap fixes first.

The shop ran an equivalent to Sea Foam though my intake vaccuum line--which it did blow some smoke out the exhaust. But not enough to probably make any difference. But I think I should probably buy the actual Sea Foam product itself and run it through. Would it be different on my TBI motor versus your carb'd motor? Where exactly do I need to use the Sea Foam on my TBI engine?

It was fully warmed up for the second test. The O2 sensor was replaced a couple of years ago...maybe I need to get another one? I'll check to see how much an O2 sensor is, if cheap enough I'll just replace it anyway regardless. I did install a breather unit on the left valve cover in order to remove the blowby smoke going through the pipe to the intake. The car runs 150% better now having done that. No more oil in my intake pan!

Thanks for the help guys. I'll report back next week when I go for another inspection test. I'll have to pay for another one because I accidently let my 15-day free retest time limit expire.

I'm almost tempted to just either BUY a sticker or get someone to somehow "pass" my car's emissions. *cough*

 

Subscribing...

 

with co numbers that high i would say cat. conv. deffinately.

 

I should know tomorrow whether or not my car passes emissions. I'll post my results when I find out.