Emissions (Nox) help

[Oldsmobuick]

Help! I just failed an emissions test in Rhode Island. Hydrocarbons and Carbon Monoxide are Fine! Oxides of Nitrogen (Nox) are not! 4.05 gpm actual versus allowed 3.20gpm.

1987 Buick GN, stock chip, stock injectors, stock turbo, recent valve job. K&N conical intake, Poston High Flow Catalytic Converter, adjustable fuel reg set at 35 psi.

Car runs smooth, strong, and great. Idle seeks a bit in open loop.

Where do I look?

I am told EGR, and here is what I have done so far.....

There is no knock (detonation) from idle to WOT at this fuel pressure! The motor is soooo strong and smooth!

Tested EGR valve with tester (result ok), cleaned EGR port and installed new gasket. Installed new EGR solenoid.

I do have a concern.... I have 2 vacuum lines open, and no idea where they go? Know where to get a vacuum diagram for the 87?

Any help would be appreciated!

I have 30 days!

 

[NICKG]

this is what i would do

1: install a colder t stat. the reason is that nox is a function of heat. so by cooling the engine a little better, you should be able to get it by
2: make sure that the fans are running(you can do this by simply turning the ac on) when the tests are conducted(including the heater on full roast) again to cool better
3: colder plugs
4: dry gas(don' t laugh, it works) it cools the combustion chambers so as to limit nox
5: add 1-2 lbs of fuel to cool the mixture(tricky ..do not add too much or you fail in hc)
6: new o2 senser get a new bosch unit(less than $35 retail)
7: bribe the guy if every thing else fails
good luck nick

 

[Oldsmobuick]

NICK G,

*I have the 160 degree stat installed

*They test without me there, so heat or a/c on might be tough?

*What is the coldest plug?

*I'll definitely do drygas!

*I can easily change fuel pressure

*I will buy the bosch o2

* I may bribe the guy if I have to (Omaha steaks, or booze?)

 

[NICKG]

omaha steaks rule!

with the het wave we had lately, you may want to just try again in week or so after it cools alittle. it was 94 deg here in nj today and 94+ since monday.. as for the plugs, just pull one out and try getting thre parts guys to get the chart out, i think ac r42's? (experts chime in here) oh, you can run the heat and ac at the same toime, put the slder to defrost, and the temp on hot, click the fan on low for the blower. they won't even notice

 

[gofstbuick]

If you have a vacuum leak, you should fix it, b/c that can increase NOx by introducing extra O2 into the combustion charge. Since a car in basically stock trim is inherantly lean anyways, a vacuum leak only adds to the problem. Also, if during the test the car does not reach a steady cruise in 3rd or 4th gear, the EGR may not be that active. How far from the HC/CO limits is the vehicle reading? You may try richening the mixture a little. When you turn the FP down and run lean, you introduce too much O2 into the cat. If there is too much O2 in the cat, reduction portion of the cat will not work, b/c the cat reduces NOx in the absense of O2. The cat actually needs a somewhat balanced a/f mixture controlled by the O2 sensor to work properly. The O2 sensor will regulate the a/f mixture by overcompensating a little rich to a little lean and help the cat work efficiently. Sorry for the rambling, but try richening the mixture a little if you have room to move up in HC and CO

 

[WarpSpeed]

Describe where the vacume lines are that you don't have hooked up. They aren't to the egr solenoid are they?
You'll get better results with an AC Delco O2 sensor, but they're more expensive. It doesn't sound like that's the problem.

You might try a can of G2P, like from pep-boys,, It's garranteed to pass.

 

[BLACK6PACK]

Hum,
that is about the opposite of what I did to pass.

I turned the fuel down as low as possible and let the car get as hot as possible (over 200*).

I did the G2P from pep boys and it worked.

Get the Delco sensor, they are only $25 at ramchargers. I have used the bosch in a pinch and it worked fine, kinda hard to fit since they are so long.

 

[gofstbuick]

BLACK6PACK
I don't know whether you noticed, but Oldsmobuick is having a NOx problem only, and it's quite possible the engine maybe running too lean. Especially if there is a vacuum leak involved (then the vacuum leak needs to be repaired first. Look at this link and there is a chart in it that describes how the 5 gasses (HC,CO, NOx, CO2 and O2) react around stoichiometry. Especially look where Nox is when the mixture is less than 14.7:1 (slightly rich). I hope this link works.
www.motorage.com/edindex/1200feat1.htm

 

[BLACK6PACK]

Yeah,
I forgot to add, that if you have a vac leak then that is the first thing I would fix. As stock as you say the car is, I would suspect that that is where the problem lies. I had quite a few mods when my car failed, but the G2P I bought at pep boys helped, but that is just a band aid for something that is wrong with the car.

 

[Oldsmobuick]

Continued Nox (vacuum line) search

I have 2 vacuum lines that are open?

1.)located in a cluster right in front of the fuel regulator (hard pipe metal tubing)
It is the only one that goes vertical.

2.)located on front passenger side top of valve cover. It is what appears to be a solenoid with only 1 vacuum line to it.
Is this the wastegate solenoid?

 

[gofstbuick]

The vertical line goes to the fuel pressure regulator, the horizontal line below it goes to the fuel evap cannister and the solenoid on the front passenger side valve cover is the wastegate solenoid.