CA smog results...help me find out whats wrong with my car...

[Oaktown]

Hey all, well my car did PASS, but barely...I want to find out whats wrong with it. Here is what it measured in the Emissions test

(CO2) (O2) HC (PPM) CO (%) NO (PPM)
15mph 14.6 0.2 110 0.13 194

25mph 14.7 0.1 79 0.11 147


It passed but they said barely in the HC part. Also, tonight I got a code 13....O2 sensor...does it read as good here? I dont know what this stuff means really...hopefully someone can help me get my car running better. If you need anymore info. let me know. It is a 87 GN, pretty much stock...has 3in. headers/downpipe/exhaust...

 

[gofstbuick]

I would suspect that if your O2 sensor is a little slow, then you may encounter a problem passing emissions. The factory O2 is a narrow band type and tries to maintain th mixture within a narrow range of 14.5 (slightly rich)-14.9 (slightly lean):1 mixture. Thus attempting to insure that rich mixture will help to control NOx and the lean mixture will control HC and CO. The speed of the ECM is quite slow, but IMHO, the rate of change of the O2 sensor needs to be the same or faster than the ECM. Personally, I like to see changes from full lean to full rich in less than 100 milliseconds. Probably changing the O2 will help emissions.

 

[Oaktown]

I found out that the 02 sensor was last changed on (3-12-01)...and about 15K ago. I guess it could be bad, huh? I am going to change it....but which one should I get? I was looking in Kirban and I see they have one for a stock GN and one for the GNX. My car has some mods...headers, exhaust, downpipe, 36 lb injectors, k&n...which one should I get....or maybe you have another recommendation?? Let me know. Thanks!

 

[gofstbuick]

I use a factory GNX O2 sensor. I prefer the factory emission parts (if available). IMHO, the factory parts were used to pass the rigorous federal Test Procedure Test (FTP), so I fail to understand how an aftermarket part can hold up to those standards.
Example, examine a aftermarket EGR valve and it is usually supplied with metered washers to control flow. Don't you think if the factory thought they could pass the FTP by using a metered washer, they would have used that idea and mass produced the same EGR valve for many different engine configurations.
This may cause some arguments, but I have witnessed the poor emissions performance results during CA I/M240 proto-type program. So I will always use factory emissions parts when available.

 

[Oaktown]

So I guess I am going to go for the stock GM GNX one out of Kirban...I will let you know how it goes. Thanks for the info. gofstbuick.

 

[TurboJim]

Originally posted by gofstbuick
Example, examine a aftermarket EGR valve and it is usually supplied with metered washers to control flow. Don't you think if the factory thought they could pass the FTP by using a metered washer, they would have used that idea and mass produced the same EGR valve for many different engine configurations.
This may cause some arguments, but I have witnessed the poor emissions performance results during CA I/M240 proto-type program. So I will always use factory emissions parts when available.

I agree 100% Joe.....

 

[Oaktown]

I am waiting for the GNX O2 sensor to come. Before I put it on is there anything else I should look for? what fouls up the 02 sensor? i talked to the guy i bought it from and he said had changed it twice in three months...now i got the car and i am suspecting it is bad...it has been 15k and 2 years since it was changed...I just don't want my new one to go bad...anything else i should look for?

 

[gofstbuick]

Leaded racing fuel, volitile RTV sealant and coolant can poison a O2 sensor. How come you have to wait so long for a O2 sensor. I just picked one up at my local GM dealer. If you need one fast, just email and I'll loan you my new one until yours comes in.

 

[Oaktown]

thanks...I dont need one fast or anything. Im in no hurry...the car can sit...i got others too drive...