1. So what do you guys make of these NOX numbers.

2. So can anyone help me with leaning out my car? I just need to adjust my TPS right, but I have no idea how.

3. Can a Mod change the name to "Passing the SMOG TEST! made simple"

I'm no smog expert, but from what I understand about high NOX, it can be caused by running to lean. But you passed the NOX test. Right???? I've seen similar figures on one of my cars I'm runing straight E85 on. Seems the NOX on that/those cars is running higher NOX than the cars running on straight gasoline like the jpg I attached earlier on this thread.

Setting a TPS is simple on a 1986 non turbo car (I have one of those also, among others). It's important to fully warm up the engine. Then go to the TPS electrical connector. Find the green/red wire on the EM harness side of the TPS plug. Put your digital meter on vdc and its negative lead on a known gnd point like the alternator housing etc. Then backprove the green/red wire with the other meter lead. The reading should be approx 1vdc. If not, then turn the TPS screw til the meter reads one volt dc. You leave all elect connectors connected when doing this. Use a sewing needle or paper clip to backprobe the green/red wire when doing this.

Remember, the engine HAS/MUST be fully HOT when doing this due to the waterthermowax effecting TPS readings when the engine is just warm/cold/tepid.

I'd also buy a cheap timing light if you don't have one. Then with a fully hot engine, check the timing. The timing might also be effecting your NOX (I'm no expert on emissions).

Your 1986 does have a EGR valve that is meant to lower NOX. That said...........all the EGR valves are removed on my 86-87 cars and I've no NOX problems passing emissions. See my results I posted in a earlier thread.

Also, do you have the 02 readings from Your test? Are the 02 reading sort of high or near the limits required????? Higher 02 readings mean leaner burning from what I"ve read.

i passed smog with... 0 to <10 on ppm on all 3 sections usually....
why not just get your car to run.... right?

Hailers is right (obviously :P) about the NOX it is indeed produced when the combustion temperature is too hot (lean condition) it is produced at 37000 degrees F. Any hydrocarbon burning to hot will produce this gas and it is a greenhouse gas hence why its on the test.

1. NOX is affected by timing. advancing the timing raises NOX. leaning it out might raise NOX too, but it also causes misfires, which shoot CO and HC's thru the roof, in other words NOX isn't really a problem

2. adjusting the TPS is very simple the shop manual is the best way. www.foxed.ca

wrong, nox is produced at anything over 2500 degrees, the higher the nox, the higher the combustion temp. the EGR is responsible for cutting the temps down by recycling intert combustion gasses to cool down the temps without changing the AFR.
yes, its a green house gas, and its a way for tech's to be able to determine the efficiency of the engine.

Lloyd

37000 degrees? you know thats 10x the melting point of steel?

nox is not affected by timing, it CAN be, but most of the time, no. for the most part, nox is produced from either a failed egr, or clogged passeges in most piston engines. i have seen multiple engines with retarded timing 2-4 degrees with the nox over 2000. the egr and intake passages were clogged, 93 300zx. the egr was failing too.
anyways, leaning out the engine will produce nox, but timing is not the main culprit.

this whole thread needs to be closed, it was a stupid thread to even start.

Lloyd

i don't know if timing is the main culprit, NOX isn't usually a problem.

i DO know if you advance the timing a few degrees, NOX goes up. one of my friends cars has always almost failed on NOX since we put it together, and the only thing not to specs is the timing is kind of advanced.

mine, which is the same (both blue 87 gxl's with ABS, and cloth) has really low NOX, on stock timing.

the HC and CO numbers are basically the same between both cars. i took both cars to the same place too...

EGR on a rotary is not configured like a piston engine, the rotary has a lot of exhaust gas dilution, the EGR valve really doesn't do much

LMAO that was a typo its 3700 degrees Celsius as per my Ontario Drive Clean handbook. That was one of the questions on my test which I got right.

guess its different in cananda, eh?
in cali, which to the best of my knowledge has the most strict emissions standards in america, its 2500 degrees according to the governing body, and on the test and every single shred of anything nox related papers.

Lloyd

okay guys i bought my car and the guy told me it passed smog, i still had a pretest done.. turns out it was passing.. so i let the technician go through with the smog...
now the car is a gross polluter... :(

I need help i want to use the alcohol but what do u guys think i can do...


HC(ppm) CO(%) NO(PPM)
rpm | %CO2 | %O2 max gp meas max gp meas max gp meas

15mph: 1863 | 13.3 | 0.9 85 296 327 0.54 2.26 1.48 565 2014 128

25mph: 2071 | 12.9| 0.8 67 246 468 0.45 2.15 2.21 522 1814 123

good info, should be archived

Do what i did and follow my instructions! Just run your gas down to empty. Dump in 1 gallon gas and one gallon Denatured alcohol. get to the smog test station after your car has fully warmed up and dont turn off your car and do the test. try to have another gallon of half premixd so if they make you wait a long time you can dump that in and be sure to have enough gas to finish the test. and when all done fill up with gas right away.

okay man im going to try it then thanks

I used a new cat and a corvette electric airpump. Then everything else was block off plated.
I almost passed as zero emissions.

wow!!!! lies!!!
u have got to be joking

^ I'm az but I have the same dyno tests as you guys.

I thought I failed after they only drove my car for about 1 minute and shut it down.
Turns out it just ran really clean.

although I'm now under collector car status and don't have to pass :P

I love Oklahoma

Why is this thread still active? Fix your fucking car and stop trying to cheat the test.

That sucks, no place it says that you haveto run petrol, if you passes and the car run's it doesn't matter what makes it run :D That's how it is here in Norway anyway :P

just as an update i took an S4 NA to smog, and it failed, the first test was

24-26hc's 0.06 co and 800NOX, it failed NOX.

looking over the car, the timing was 10 degrees advanced over stock, setting timing to stock got me

24-26hc's 0.06 c0 and 600 NOX, which almost passes, but not quite.

the smog guy suggested changing the o2 sensor, i didn't want to, because the car has ABS, so i built the LED o2 tester, and sure enough it was dead.

new O2 knocked Nox down to 230. i left the O2 LED's hooked up for the test and it is actually in closed loop for the test.

HC and CO came up to 30 and 0.08. so now the car passes very easily. precats are gone and the main cat is in horrible shape.

next time i'll leave the LED's hooked up to the emissions solenoids, so we can see what the ACV does, i've been pretty sure its in port air, but driving down the street @2800rpm its in relief...

i have an older Bonez cat that is about 5 years old, used for emissions testing but has low miles and clean.

i have a T70 turbo, streetported, microtech LT8 with 720/1600 injectors, walbro pump, FMIC, black magic fan putting plenty of electrical load on the engine, 3" single exhaust turboback plus a few non essentials that might effect emissions in some way.

the law in nevada states you must have the underhood emissions equipment fitted to the engine(visual), have the timing set properly and pass the tailpipe test. i install the smog pump and run the line to the catalytic converter and run the test with no changes to my microtech maps. fortunately the law doesn't state that the engine has to be original, have to use original parts, run the stock ECU, exhaust, intake, yadda yadda. technically i could install a 20B, fit the emissions basics, pass the car and drive it year round without worry.

result is usually around 50% or less of the maximum allowable limit. we're allowed 200HC, i'm usually under 100, sometimes near 0 depending on whether the e-fan is running during the test or not. this all with air pumped before the tail section of the 3 way cat, no precat, no air dumped into the exhaust ports, just a decent tune, warmed up engine, idling. (well i do retard the timing back to 0 for the test otherwise it is at about 15* of advance at idle, tune is set to approximately 325-350whp@15psi. figures are low because of the pressure drop across my restrictive intercooler)

running the car with no cat, judging by my nose it is pumping out about 300-500HCs idling, well beyond failing and i cannot clean it up much further than that or it will hunt/stall. retarding the timing would help to possibly get it close enough, but almost all states that require testing also require timing be set to factory spec.

So, if you ran with airpump going constant to the split air pipe/to the 3-way cat, remove the acv and block it off, new cat, engine in good shape tuned stock--good possibility to pass (assuming everything else is as it should be)?

pretty much

done it that way 2 years here so far and haven't had it fail due to emissions level.

I did the same thing. Not sure how busy your DMV is but we have long lines I ended up cooking my cat from idling too long waiting in line cause I was worried it wouldnt be warm enough with the air pump. It was fine going down the highway and had no weird smells going back and forth. In hindsight I would probably disconnect the airpump going to the split air pipe and put it on right as I get to the DMV, then let it idle for a minute or two before I go through the inspection lane.

When I passed my HC was nearly 0. he gave me a funny look so I told him its a 1.3 liter. hahahah