do you know what the maximum allowable HC is?

 

HC passed. CO2 passed. its the NOx part that failed. and no i dont know what the max. HC is... doesnt it say it on the paper?

 

no it doesn't.
Can you pull your plugs and post a picture of them?

 

i will tomorrow, i have a lot of cleanup here to do. we just got a big dumpster cuz we're remodeling, and i have a lot of crap to pick up. theyre less than 2 weeks old though. do you need just one plug, or all of them? cuz i dont mind pulling all but the last plug. the #4 plug is a PITA to get out and get back in. why i dont know.

 

It appears the NOx test was done on a dyno at 15 and 25 mph and varying loads to the wheels no? Given that as true, perhaps the EGR valve is not opening, which it should be in this case. You'll need some way of verifying that the EGR is operating- disconnecting the vacuum hose isn't going to do that. You'll need to apply vacuum to that port on the EGR valve while the engine is running and check that the engine begins stumbling and possibly dies. If that happens, the EGR valve itself is functional, but not getting the vacuum signal to open.

 

question. how do i apply for a one year waiver/extension in california? i cannot afford the smog repairs, if its not the EGR. once i start working, then ill be able to, i just cant right now. any ideas?

 

http://www.bar.ca.gov/01_ConsumerAct...icleFails.html

 

so i gotta get it smogged again, then ask them for the economic hardship waiver paper?

 

Or you could just push up on the egr diaphram with a small screwdriver, your finger or some people on this site like to suck on the diaphram hose.
You can do it like this, well kinda this is off a 3vze and it's off the car. But still easy on car. Just make sure you push on the matal and not the rubber.

 

Look at the very first reading on the chart. The driver has it sitting at 0mph revving at 1500 rpm and his Nox are through the roof.

So then somebodys gonna say that the nox doesn't ever really drop off either.

Look in the middle the first reading just after the line drawn across
-the speed increases to 25mph from 15 mph
-the rpms increase from 1500 to 2500
-the nox levels increase only by about 2-250 ppm to 2200 ppm while in comparison with rpm you'd think they should go up to roughly 3000-3500 ppm
-the HC's drop dramatically, almost in half. I can't really explain this one but sometimes you just look for signs that stick out.

I'm gonna say that looks like the EGR is working.

Back to my original point I think it's a carbon build up problem, it's just a hunch. Then again if his threads on his #4 spark plug hole are all festered and he needs the truck on the road, It'd probably be a good move to try to find one of those smog loopholes to go through.

Oh and another thing. In his vehicle write up he mentions that he's got roughly 260,000 miles on the original motor. Unless he's running it on propane, I would definitely suspect carbon build up.

 

the threads arent screwed up on spark plug #4, its just a pain getting a socket and a ratchet back there. once positioned right, it threads in easily by hand all the way. so should i put my old spark plugs in, run a can of seafoam through, change the oil, then get it smogged again?

 

Funny, mine failed almost exactly like yours, extremley high Nox right at the start, then it dropped a tad and just stayed constant.

I would start testing your vacuum hoses, replace any that are cracked and check that egr modulator.

Do you have access to the past tests done on the truck? If so, check them out. I can see my trucks smog reports from 6 years back, and i watched my Nox get slowly higher each year till it went over the max...

 

that i dont.

 

How would your EGR, EGR modulator or vacuum lines affect your nox readings during low speed/rpm?
Please explain.

 

i dont know, im tryin to figure that out too

 

I can't exactly say, but replacing the modulator fixed my issue..

 

I thought that for a moment too, but then noticed that it went from 0 to 15 in 2 seconds, CO2 changed from 0 to 14.2%, RPM didn't and the torque load of the dyno went down so I attributed that to the test equipment sensors coming online and beginning logging.
Okay. It doesn't ever really drop off either.
Possibly the ECU going into closed loop? Either way, HC's are passing, and are somewhat consistant at each speed.
I'm going to say it's not. Two reasons: no significant reduction in NOx, in fact an increase at 25mph; his ecu is throwing an egr related trouble code. I'm going to go so far as to say it's not opening.
I might agree on some carbon in there too. As for it being the cause of the problem, I don't, unless it's carbon causing blockage in the EGR passages. If the EGR were working, you'd expect the NOx to drop at some point in the test, which it doesn't.

I am actually considering the converter as a suspect as well.
-edit: okay, I figured I should elaborate...
Theory: partially plugged converter increases backpressure sufficiently that chamber temps rise.

 

One thing I have found is that there is varying degrees of "EGR working". My '85/22RE engine would stumble/die if I manually operated the EGR with a vacuum source. However, it would not drop the NOx low enough to pass the dyno smog test. What I found was blockages inside the EGR passages (in the head and the valve itself) that were limiting the actual flow of exhaust gas. In order to affect the engine running at 2000-3000 RPM and at fairly high load from the dyno, it takes a lot of exhaust gas to flow back into the engine to drop the combustion temps/NOx.

I spent a day cleaning out the internal EGR passages in the head and also in my LC Engr. header that had some restrictions that I ported out for better back flow. Also cleaned the inside of the EGR and the modulator. Then to help reduce NOx further, I fillled up w/ 92 octane gas and retarded the timing from 5-BTDC to down to about 1-BTDC. All that dropped my NOx from ~2400 down to ~800.

 

will seafoam clean the passages if intoduced to the PCV?

 

Due to the co2 levels it's looking like combustion is complete. So I'd right off the cat clog issue. Even if it was an issue, it would probably be accompanied with a lack of power or misfiring complaint.