Went down for a smog here in orange county and failed, on nox. 1185 I think. Hc were like 24 and co was 0. pretty close on both speeds.

1985 2.6 mechanical valve lash adjusters.

Motor is new 150 lbs compression, cat is 2 years old and check good by doing the 10 second crank with cat hot and coil disconnected. Egr valve checks good, vacuum applied at idle, motor stumbles.

The head was milled considerable when the motor was rebuilt and the cam is lower profile than stock. (low performance) 19-20 mpg hwy. I have picked up a stock cam out of a 86 caravan, and will install it soon. Will this fatten up the mixture enough to bring down the nox? I'm close enough to passing that I don't want to make it worse.

Engine runs slightly on the cool side 180 therm I believe.

I checked previous smogs certs and the nox has always been over 1000, they just tightened the standards.

What can I do to lower the nox prior to my retest. Will runing premium help? Gas additives? Timing? (allowed 2 degree varience). Or just hook the egr up to manifold vacuum to keep it wide open? It functions at different rates at different RPMS now, but will opening it full bring my nox down enough. If I can drop 100 I can pass.

Any suggestion will be apreciated.

I also have an 87 exhaust maifold and y pipe (not installed yet), to get rid of the provision for the cat in the manifold, how will this affect it? No cat in manifold at present, just welded in downstream

Did it fail at idle or at speed? The EGR ports on the intake are prone to clogging, remove the EGR and check the ports. Make sure the cat is hot as hell <img src="/forums/images/graemlins/evil.gif" alt="" /> 30 minutes of hard driving and don't let it cool down before testing.

Last resort,

I'm sure you can pass with "special gas" run it down to 1/8 a tank and add a gallon of denatured alcohol from the local hardware store. Get it checked and then fill up, you don't want that strong of a concenstration in there for long.

<img src="/forums/images/graemlins/cheers.gif" alt="" />

...but also make sure the engine is COLD. High combustion chamber temps ususally cause the NOX to raise.

There's a barrage of tricks you can try, and combining them all together should make sure you pass.

Flush the engine with an engine cleaner, as well as the fuel system, and change the oil. Your HC and CO are low, so you could run a lower weight if you wanted. Get spark plugs 1 heat index cooler than your current plugs. Drain the coolany and add 100% water with 2 bottles of Redline Water Wetter. Unfortunately, I'm not sure how to make it so the mechanical fan stays on the whole time (I've always had electrics so I just switched them on). Double check your ignition timing (though they probably did that on your first attempt, so you know if it's on or not).

That should be enough to pass you. Our trucks are notoriously high with NOX readings from posts I've seen in the past. Those tricks worked for me last year. Let's see if they work again this year! <img src="/forums/images/graemlins/coolg.gif" alt="" />

SoCal,

I believe you only need to smog every 2 years in CA.

Ray

I would make sure your thermo valve is working so that the EGR is actually opening under usage. Of course verifying the vacuum lines. Make sure you are in closed loop when warm under load with a volt meter on the O2 sensor.

The camshaft will affect NOX. Less overlap (smaller cam for more tq) reduces the amount of residual exhaust gas left in the combustion chamber at low and intermediate speeds. This will raise combustion temps. Camshafts were modified with more overlap way back when to reduce NOX. This is a built in EGR system and predates the external valves.

You can also look at you dist for stretched out springs and or a loose advance mechanism.

Also look for vacuum leaks.

can you post the other numbers from the test ?

Kevin

Sounds like some good techniques mentioned.
So here is how it did.
M1 15mph(rpm 1756)(co2 13.2)(o2 3.5)(hc 29)(co 0)(no 1935)
M2 25mph(rpm 2736)(co2 13.8)(o2 2.6)(hc 8)(co 0)(no 1153)

and this is the standards.
15mph hc max137 Ave43, co max.94 ave.16, no max1107 ave406
25mph hc max109 ave32, co max1.19 ave.15, nomax1163 ave349

I was concerned about the cam. It seems to run lean so to speak. I do like the fuel economy however. I just need it to pass and then I may put multi point fuel injection on. I have a wolf 3d fuel management system already and it is totally programable. It can pre programmed for performance or economy and it saves the setting so you can easily change back and forth.

De natured alcohol, how does this work? Sounds like the cheapest plan that insures passing if it truly works.

I do need to check the o2 sensor, although it is only a few years old. So when you say closed loop, you mean zero resistance when hot right? Like shorted? What about when cold. I missplaced my manual and can't reference at this time. Or does it produce voltage like 1 volt? I forget.

EGR passages and valve are all working, weather or not the control switches are working correctly is another question, but has passed with it configured this way other years.

I may try one step colder plugs, but won't this also affect my hc?

Changing the cam is going to happen, just is it prudent to do so before testing or will it actually help the test. I have got to get some photo's of the lobe profile for you to look at as I think the duration may be longer than I want. The lobes are more round than pointed, and seems strange. The caravan I pulled it from had recent head work and the cam looks new. No wear so to speak, clean like new etc. could be a performance cam unwittingly put in the caravan and then couldn't smog so it ended up in the boneyard. In other words, questionable origin for smog purpose.

Just got off of the phone with the Ca smog people. One of their tech's said I could run methanol and make sure timing is not advanced. Also mentioned that their are some CARB (California Air Resource Board) approved water injection systems that would work too.

Now that is one I can live with, more horsies and pass smog.
Anybody know of a good water injection system?

I wish that were the case. If I was driving a 2003 Honda Civic, then yeah, it owuld be every 2 years. But my luck wiht my last 2 cars has been such that they have asked me to re-test after ONE year, because my vehicle is "AT RISK" for being a polluter. This time, with the Montero, they are right...HC and CO were fine when I smogged her upon purchase and title transfer this time last year, but NOX was off the chart and my first test went in an a Gross Polluter. I passed on the re-test.

I am assuming that I will need to test again this year, but I need to make some phone calls. My tags are due this month, and I have not received anything from the DMV about renewal! I am prepared to smog if they ask me to. <img src="/forums/images/graemlins/wink.gif" alt="" />

It might slightly, but you're so far in the green that you have wiggle room here. Take some from HC and give it to the NOX.

And forget the water injection. That's not really what it's designed for anyway (unless you're running more than 15 pounds of boost), and it's hard to set up just right. Takes a lot of trial and error. You could actually make youre emissions worse if you're squirting too much water, or even blow your new engine up (water doesn't compress like your A/F mixture does, compression skyrockets, temps go up, and stuff breaks).

This formula will make almost any car pass smog no matter what:

New cat, oil change, engine flush, pass or dont pay additive, new plugs, water wetter, rad fan constant on.

Some of that might be overkill, but that has ALWAYS worked for me and many of my friends, no matter what the problem was. And my problem has always been NOX. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Check out my post from a while back. I had the same problem.

http://www.4x4wire.com/forums/showf...oldertype=m&bodyprev=#Post190360