Other gases were excellent,but the NO was 1597 and 1244 with MAX readings 1020 and 880. Really don't think it's the EGR. Could be carbon build up or those tiny emission hoses missing or cracked.

A ton of start and stop city driving on this ride. Any suggestions?

 

Your NOx shouldnt have been that high unless something is wrong. First suspect is the EGR. Second is the cat. Third is timing. I seriously doubt carbon buildup is causing it. The high NO readings are either from it not being cleaned up by the cat or the likely cause is combustion temperatures being too high. EGR is supposed to lower combustion temps. Carbon can cause hot spots and detonation, but its unlikely to affect overall cylinder temps enough to send the NOx up.
A vacuum leak from cracked hoses could cause it but usually it throws off the CO if I remember right.

So, did it get sent to Sac or did you have a pre-test done? I sure hope Sac didnt see it because you can end up having problems and going to a test only station if those readings are too high... I cant remember how high it can be before they tag the car. If not, I know someone off the 55 and McFadden that is pretty good and can probably trace it down for a reasonable amount.

 

For the last two smog times I've had to take my car to a smog only station ( since the test only incarnation). I was under the impression that a lot of camaros are having to go to test only cars. I think they make the cars that have a history of failing (as a group) and make them go to test only. With 216,000 mi on the engine last time I got it smogged, I was glad to see a 92 integra in mint condition fail be fore me


James
Westminster, CA

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1985 Z-28 305 TPI
221,000+ mi., Original Eng.

 

Its kinda weird.. if you didnt pass the last time until the car was repaired, and its an older car, you get nailed. If you have a computer controlled carb car, say hello to test only. I have yet to see one of those get away from a test only station. They are basically picking on older GM's and Fords, especially early-mid 80's.

 

 

NOx is formed By High combustion Temperatures.


Check your EGR, as its function is to lower combustion temperature.

Also, The leaner you Run, the more NOx is produced.

The Cat Combusts Uncombusted Hydrocarbons, So that is not likely the cause.

I would really suspect the EGR. If not then Check your mixture.

Its a TPI ? What sorta shape are the injectors in ? fuel rpessure ?

How does the car perform ?

that is a insanely high Nox reading, indicating that something is way out of whack.

for comparison, My Lg4 car passed Nox with 64ppm, as compared to your 1597.


What mods Have you Done ?




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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Just another Hot Rod kid, or thats what they all tell me.
Livin' the Stereotype

 

The cat will clean up NOx. All the cats on thirdgens are 3 way, which is HC, CO, and NOx. Its not real effective on NOx but it does work. I do agree its probably not the problem. If the oxygen reading is high (like around 2%) then the cat is bad. The oxygen should be about 1%.

 

Other readings were HC 60 and 50 with a Max allowable of 133 and 83. CO was .02 and .01 with a max of .71 and .58

No major mods. Recently put in new intake gasket and took off the A/C. Did not reinstall small emissions tubing in some areas.

Do I check the EGR which is a pain because I need to remove plenums and fuel rail or deal with the cat?

 

You dont have to take off the plenum to check the EGR. Apply vacuum to the line and the car should die, that will tell you if the EGR is ok. Theres a procedure in manuals on how to check if the solenoid is working, its not complicated but theres a bunch of steps and I dont remember them all.

What tubes did you leave off, and did you cap off the ends so there were no vacuum leaks?

 

Did you leave off the vac. tubes to the EGR??

If so, this is probably where your problem lies.

We don't test for Nox in our area but the rumor is that if the EGR isn't working, the machine will know it. Its that sensitive.


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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

R.I.P. #3
My favorite quote about D.E. "He can see air"

[This message has been edited by Engineboy (edited March 11, 2001).]

 

Are you sure we dont test for NOX here, engine boy ?

I could swear it was listed on my last smog cert...


Hmm.

------------------
60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Just another Hot Rod kid, or thats what they all tell me.
Livin' the Stereotype

 

Some of the newer machines in the area are capable of testing and are reading the NOX, but its not required as a pass or fail point.

Only areas that NOX matters is in an "enhanced" area.

------------------
ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

R.I.P. #3
My favorite quote about D.E. "He can see air"