emissions test

[1BUICKGN]

I just got back from the local gas station that performed an emissions test on my gn and it failed the test. i was wondering if anybody has any ideas on lowering my results.
reading: limit:
hc gpm 03.11 02.00
co gpm 054.86 030.00
nox gpm 03.57 03.00

i don't think my gn1 heads and 72psi injectors are helping any....
i'm currently running a full exhaust with cat and the fuel pressure is set at 44psi with the line off.

 

[RatFink]

Aren't cars 20 years old or older eligible for antique/classic car status, which makes it considered a "play" toy for weekends only, then making it exempt from emmisions tests? This may be rumor, BS, or only in some regions of the country. I hate emmision testing, good luck.

 

[1BUICKGN]

I will have to check into that....:biggrin:
thanks,

 

[turbojd]

What chip is in the car, and is your EGR working?

 

[TurboDave]

I just got back from the local gas station that performed an emissions test on my gn and it failed the test. i was wondering if anybody has any ideas on lowering my results.
reading: limit:
hc gpm 03.11 02.00
co gpm 054.86 030.00
nox gpm 03.57 03.00

i don't think my gn1 heads and 72psi injectors are helping any....
i'm currently running a full exhaust with cat and the fuel pressure is set at 44psi with the line off.

Since you failed across the board, your cat isn't doing it's job, and likely because you didn't get a smog chip burned for your injectors, so your probably running in open loop most of the time (bad thing for smog), and I seriously doubt those heads even have and EGR capability, so you're pretty much screwed from the get go.

To get the kind of numbers they're looking for you're going to need be full time closed loop minimum, real good cat., high engine temps (200°) and tight control of your A/F ratio, either with a stock O2, or a WBO2 that can control your low and mid load A/F ratio.

CAT.
EGR.
Good Chip.

 

[rug]

Here in CT cars that are 25 years old are exempt. 4 more years, i cant wait

 

[onslow]

Hi -

I basically agree with all of TurboDave's advice and comments...he knows what he is talking about! GN1 heads are not emissions certified...they are for off road use.

But, there may be hope...you just have to be methodical and thorough in your approach to smogging (as we all should be with any issue involving these cars).

The EGR valve's only function is to reduce NOX. If you have one, be sure it is working. The EGR vac valve and filter should be functional.

Follow his advice re the O2 sensor. If you already have a stock sensor, make sure it is working properly. My BLM tended to run very high at idle (151). When I pulled the O2 sensor, it was all coked up. Put in a new one and BLMs came right into line at a neutral 128/idle.

When the car is tested, it must be in closed loop. My smog guy lets my car idle for 10 minutes to get the car into closed loop (I demand it) and get the cat really hot (200+ would be great; mine passes at 190) before he begins any tests.

Closed loop mode means the ECM measures the A/F ratio and uses it keep the ratio at 14.7 to 1. Closed loop uses feedback from the O2 sensor to close the loop. The reason for getting it closed is that a 14.7 to 1 ratio allows the cat to REDUCE EMISSIONS MOST EFFICIENTLY. If the car is in open loop, the ECM controls the injectors but does not get any feedback that the calculated fuel delivery actually matches what the engine got. Without feedback, the loop is "open" and the car will run richer or leaner than 14.7.

Also tell him to test car in Drive, not Overdrive.

Check the cat...bad cat = no pass.

Go to turbotweak.com and check info re smog chip.

And, do the basics. Clean the up pipe, clean the intercooler, new plugs, plug wires should be carrying good spark and coil pack should be sparking well, change the oil & filter, new/clean air filter, new PCV valve (if you have one with those heads), clean valve cover breathers, make sure turbo is not coked up.

All of those things should be sorted out for a strong, efficient car anyway.
My car is stock, but we have Draconian smog tests here in Calif, so I cover all the bases.

Let us know how things work out.

Good Luck!

Steve

 

[onslow]

Hi 1BuickGN-

Just occurred to me, some guys have had good results with a chemical product called Guaranteed To Pass (G2P). I used it on a hi mileage car some years ago and it worked well.

But, it is not a substitute for doing the foundation work on the engine systems first.

Steve

 

[1BUICKGN]

What chip is in the car, and is your EGR working?

i'm running fast xfi instead of the stock ecm.

 

[1BUICKGN]

Since you failed across the board, your cat isn't doing it's job, and likely because you didn't get a smog chip burned for your injectors, so your probably running in open loop most of the time (bad thing for smog), and I seriously doubt those heads even have and EGR capability, so you're pretty much screwed from the get go.

To get the kind of numbers they're looking for you're going to need be full time closed loop minimum, real good cat., high engine temps (200°) and tight control of your A/F ratio, either with a stock O2, or a WBO2 that can control your low and mid load A/F ratio.

CAT.
EGR.
Good Chip.

I have been considering a new cat,195 thermostat(180 now),lowering the fuel pressure and changing the a/f ratio.

 

[1BUICKGN]

Hi 1BuickGN-

Just occurred to me, some guys have had good results with a chemical product called Guaranteed To Pass (G2P). I used it on a hi mileage car some years ago and it worked well.

But, it is not a substitute for doing the foundation work on the engine systems first.

Steve

I have a bottle ready for the free retest.....

 

[1BUICKGN]

You guys have all been a big help in different ways....
getting this car to pass emissions is kind of a long shot..(gn1 heads)

 

[TurboDave]

Well, one thing's for sure. You wont have any EGR functionality with that computer and those heads. So you're going to have to get real creative!!
A good cat and the right a/f ratio probably isn't going to be quite enough. But the best of luck on your quest.

 

[Mac in SD]

Just get your HC down (lean it out and good cat), and put a couple of bottles of HEET in a half tank of gas for the NOx.

 

[Buzzard]

Well, one thing's for sure. You wont have any EGR functionality with that computer and those heads. So you're going to have to get real creative!!
A good cat and the right a/f ratio probably isn't going to be quite enough. But the best of luck on your quest.

I beg to differ, the XFI system he has will control the egr system, although his heads don't have egr passages, so it will take some tuning to get it to pass.
Find yourself a good dyno shop one that has a five gas analyizer and you should be ok.
Make sure that the cat is fresh and verify that it is in fact a three way, (one that has a NOX bed in it). The three way cats are a little more expensive and more restrictive than the high flow 2 way cats.
Good luck

 

[gofstbuick]

Those readings look really rich. But once you drop the CO down, NOx is going to go up more. Because you don't have the luxury of a functioning EGR system, you may look for a three way cat from a European vehicle. Most European engines are not equipped with EGR and they reduce NOx with a three way cat that has a lot of surface area. Look at the cats on a 4 cyl Porsche (for example, 944 or 968) and you will find a their cat is twice the length of most domestic and asian vehicle cats. If you also have the O2 and CO2 readings, you can plug your results into a Lambda calculator to determine how rich or lean your engine is really running. then you can adjust your emissions to perform most efficiently and then as others have suggested, add a good cat.