Failed CA Smog: NOx Too High

[salvageV6]

How did you test the valve?

Did you test it under load while driving?

It's probably the EGR operation, and you can have low CO %'s with these cars.

I never noticed much help from a Cat. with NOX emissions, EGR is a big factor there as mentioned by others previously.

I've passed with the usual cracked header with NOX numbers much lower than you are experiencing it could be hurting but I doubt it's your main problem.

 

[Ken Cunningham]

I put a vacuum pump to the egr port at idle. The engine stumbled as expected when vacuum was applied. That's about all I know to do to test the egr. I guess that doesn't prove that the electronic controller box is working.

I can "T" in a vaccum gauge to the line between the egr controller and the valve, tape that to my windshield and drive around to see if I get vaccum readings under power. Is that what you would suggest?

 

[blackstallion]

before you went back to the test center u need to check egr operation applying vacuum to the egr only test the egr valve and its passages u need to see if its getting a vacuum signal if you have a put a tee inline with the egr hose drive it to see if u get vacuum.If you get vacuum at the egr valve then put some top engine clean or seafoam to clean out the carbon.

 

[Ken Cunningham]

OK, I think I found the problem. I tried to "T" in a vaccum signal line from the 'Electronic Vacuum Regulator Valve" [that's what it's called; I looked it up]. When I pushed a vacuum line on, the top of the EVRV basically fell backwards! WTF?!

The EVRV has 2 major sections held together with 4 tiny tabs. Two of my tabs were broken, so the 2 parts were not working together. The electric signal wires come into the top; the vacuum lines attach to the bottom half. There is port which communicates between the halves, but my separated valve had no such communication.

So I removed the EVRV, tied the 2 halves together with 2 zip ties and reinstalled, along with the vacuum tap I had already prepared. I'll drive around for a couple of days with my vacuum gauge taped to my windshield to see how my repairs hold up. Looks dorky for the time being.

 

[KL Mallender]

Maybe it's a defective "Cat", lol :biggrin:

Kevin.

 

[RobS]

Your signature says you have an extender chip. I thought extender chips disabled egr operation. I would call whomever made your chip to verify.

 

[Ken Cunningham]

RobS: Thanks for the heads up on the Extender chip. That explains something I saw yesterday.

I put the vacuum gauge on and drove with the Extender. No vacuum at all.

Then I switched to a Thrasher chip. Good vacuum readings.

The chip I take in to smog with is not the Extender, and I have passed several times with this chip.

 

[RobS]

Sounds like you got your egr working again. Hope you pass this time. Good luck!!

 

[Ken Cunningham]

Finally Passed!



Fixing the EVRV did the trick.

15mph @ 1567rpm: %CO2=14.30 %O2=0.48 HC=21 (max 110) CO=.00 (max 0.72) NO=255 (max 772)

25mph @ 1946rpm: %CO2=14.40 %O2=0.34 HC=20 (max 85) CO=.00 (max 0.59) NO=262 (max 711)

 

[salvageV6]

Hollow that cat.

 

[Ken Cunningham]

Hollow that cat.

I've got one I could put on, but I don't like the sound. Too much drone.

At my level of street performance, the cat is not holding me back. The California crap gas is. I put an adjustable wastegate on to turn the stock boost down.

 

[turbolou]

Reply

The purpose of the EGR system is to introduce inert ( exhaust gas ) into the cylinders to dilute the mixture & cool combustion temps to reduce NOX. & detonation & improves mileage. This function is only desirable at part throttle light load conditions. Anywhere else in the driving cycle will cause a poor running engine. There is no perf downside if working correctly. The earlier systems on carburated cars were unreliable problematic & were better bypassed but not the case now with F.I.The black box that's tied into the EGR valve is a transducer that gets its signal from the ECU to direct vacuum to the valve when certain conditions are met. If all other readings as in this mans case were fine than there is no need to replace the CAT.Our cars also have a problem with passing HC in the test. Cold running temps. can cause a failure. make sure the engine is running at least 180- 190 when tested. Of course plugs,wires,coil pacts etc. have to be on the money also. When all this is correct & the engine runs clean & smooth it will also make good power & haul ass. Since I have maintained a CA smog license for many years I thought to share this maybe there will be less failures if people have a better understanding.

 

[salvageV6]

Good common sense information, Nick you reading that?

Although I've passed for years now with a 160 stat. in the dead of winter here in CT.

 

[Hacksaw]

a good cat WILL help with NOX, a bad one will hurt NOX.

Very true if it's a 3 way cat.

FWIW, 3 years ago my Olds Achieva would not pass NOx. It has no EGR from the factory. I already had done some chemical decarbonizing before that test, and it had 140,000 miles on the original cat, so off to the exhaust shop for a new cat.

NOx passed on retest, and HC also got better, even though it was OK before the cat change.

 

[TurboDave]

I've got one I could put on, but I don't like the sound. Too much drone.

At my level of street performance, the cat is not holding me back. The California crap gas is. I put an adjustable wastegate on to turn the stock boost down.

Don't forget to fix that cracked header, it isn't helping.

 

[bison]

Ive found that retarding timing usually improves NOx emissions since it lowers the cyl temp and throws more heat into the exhaust which will keep the cat converter hotter. I also typically throw methanol up to about 30%. This lowers CO by leaning and NOx by lowering combustion temps. I took a TR through CT emissions and at 25mph it had about 450ppm with no EGR at all. All i did was add in the methanol on that one.

 

[bison]

I should also point out that I noticed the typical d/s header crack when I did a top end engine clean in preparation for this test. I have another header already welded up and ready to install. Could this be sucking in air, throwing my O2 sensor off?

A header crack will usually increase CO since the O2 will see ambient air and think its lean when its not and will add fuel. This is plain as day when looking at light load blm numbers. They will be above 128. High CO means its rich. This shows how effective a cat converter really is at lowering emissions even when there are other things working against it. Fwiw i have had zero CO a few times and less than .1% many times with TR's and other older cars. If the engine is burning at 14.7:1 or leaner without mis fire and the cat converter is good it will have low CO every time unless the engine has a major internal problem. Ive gotten the CO down to under .2 with no cat converter by mixing in alcohol.