Failed Ca test for high Nox
AFR@ 14.75 using the calculator http://www.smogsite.com/calculators.html#lambda
so I don't think I'm running lean as in a leak somewhere

So for the smog repair guys . . .
-How do I test the egr?
-If its a bad cat . . . how do I find out which one ?

15mph @1337 rpm
CO2 14.4
O2 0.4
HC 5 (max 50/ave 9)
CO 0.01 (max 0.48/ ave 0.02)
NO 896 (max 414/ ave 57)

25 mph @ 1288 rpm
CO2 14.3
O2 0.4
HC 11 (max 34/ave 7)
CO 0.03 (max 0.45/ ave 0.03)
NO 830 (max 701/ ave 50)

 

Not sure how to test the egr without a tech 2 but you could try cleaning it. Egr is what keeps your nox down. Also check your plugs. High cylinder temps are what create nox emissions, hence introducing an inert gas into the cylinders.

 

How many miles are on your ride? I had a 98 Durango with a 5.9 and it failed twice for high NOX and i already had a low substrate metal base Cat installed... If you replace the cat shell out for the high metal substrate one.. i agree with bww3588 and clean out the egr and related items.. If i remember BG products also sells a intake/combustion chamber carbon cleaner that could help...

 

Put 3 or 4 cans of dry gas... retest!!! We do that in MD all the time. Alcohol runs clean.

 

A cheap, easy way to test the EGR is to try and push on the diaphragm inside of the EGR. If the idle stumbles or it dies, I'm TOLD that the EGR is probably good. Shoot, I had to deal with this on my LT1 Z a few months ago-I should link to that thread.

Edit: here's the thread where I tried to learn about dealing with EGR nonsense: https://ls1tech.com/forums/lt1-lt4-m...ode-p0400.html

Also, does anyone here know what emissions readings our cars SHOULD be putting out?

 

in closed loop( warmed up) your o2 sensors will trim you to stoich if its in their power regardless of fuel being used - you could run e85 and it would still trim to stoich anywhere the injectors and fuel system could keep up...

if alcohol is lowering nitrides of oxygen (nox) its either through the charge cooling you get from alcohol or the combustion chamber cleaning its known for , running a higher concentration of alcohol will run leaner if the sensors dont compensate for it and leaner is hotter , hotter is what causes nox like mentioned above

how long since o2 sensors were replaced ? if its lean and the sensors are slow reporting it that could be an issue... definately check out your egr like mentioned , maybe do a top engine clean like seafoam along with fresh o2 sensors - hopefully its not a catalytic issue for you

where your hc & co are way in range maybe you could trick it richer for the test by maybe a colder t stat , colder plugs , anything to let a touch more unburned fuel pass through...

between NOX, HC, and CO all three seem to concur you are dead lean

 

Did a top clean with Seafoam and got smoke from the engine bay
Too dark to see were it was coming from
I'll try it again in daylight and find the leak and maybe this is why there is high NOx

 

so i have a 98 engine in my 01. wasnt egr used in 98-00 to reduce the nox cuz of the cam size? and later years had a smaller cam?
how can i pass emissions without the egr?

 

any idea?

 

Isn't that a little low in RPM for the EGR to even open up? I think your results would be better if the tester put the car in a lower gear.

 

Typically, but it's all in the tune. Egr doesn't usually open up till around 2200 rpm low load conditions, but I would imagine with these cars low cruiseing rpm's, the egr would be commanded at a lower engine speed.

 

Just saw this, yes check your vacuum leaks first -will cause nox failure.

 

this ^

I mentioned earlier in this post with nox real high but co & HC extremely low the 3 are all agreeing that the car is dead lean and should have spelled out what I meant by dead lean - vac leak causing un metered air to get introduced without corresponding fuel.....

 

The driver side cat to manifold gasket had a leak with carbon on both sides of one area of the gasket.
Just replaced it
The is right behind the O2

Would this be a probable leak to cause the engine to go lean . . .
Or should I keep looking . . .

 

I'm going to say NO because where that leak is doesn't affect the A/F mixture of the engine. If your exhaust was leaking you'd just have...a leaking exhaust.

As for the poster with the '98 motor in his '01, you're kind of screwed on that one. Only thing you can do is to have EGR tuned out. I think might still show up on the smog check, although you won't fail the test. Someone correct me if I'm wrong...

 

You might also get the fans running at lower temp to
drive the ECT down. If these speeds are on the rollers
you have no rolling airflow and will run ECT way up.
Which will probably help CO/HC some, but more peak
cylinder pressure to make NOx.

 

Ran seafoam again and the top of the drivers cat that has the flange has a leak were the factory weld is to the flange (seafoam pouring out heavily)

Is the cat runined by the extra O2 that would have entered on the backpulses?
Is this a reason for high Nox failure (see other post)?

If the cat would be functional can I epoxy or have it welded?
Or replace?

 

Shop says the leak will cause high NOx and welding it will be fine
Removing it to get it welded and test again

 

why do i need egr tuned out on my 01? they didnt come with it.

 

any help?