Just got foxy (82 power ram 50) smoged today and she passed everything but nox! I need help!
Just got foxy (82 power ram 50) smoged today and she passed everything but nox! I need help!
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Here are the results
A number of possible causes - a vacuum leak somewhere, the A/F mixture isn't adjusted properly or the EGR system isn't operating properly. There is also a possibility that the plugs are the wrong temp rating, a tuning issue has ramped combustion temperatures or the combustion chambers are carboned up. If your engines cooling system is struggling this will also affect combustion temperatures (all of which increases NOx emissions).
I have the plugs is says to have the ngk plugs it has a brand new no jet valve head, head studs new head, intake and exhaust gaskets. New fuel filter, lines and new gas. New water pump fan clutch, 160* thermostat. It runs cool now. Had many problems with it overheating hence new head. Now it dosent overheat but won't pass.Originally Posted by geezer101
Gonna try to clean the egr and recheck for vacume lines. But none of that got replaced or messed with.
Also I had the carb rebuilt at a shop and never touched it cuz after they fixed that it passes lastime
Is there a possibility that my engine is running to cool and that might be a cause? Cuz it dosent get past the second white white line on the gauge
From what I'm reading up, anything that increases combustion temps will cause an increase in NOx. The EGR not working properly, lean engine tune or engine running hot will cause an increase in combustion temps.
The egr is a good place to start, carb cleaner and a set of long harbor freight bristle brushes, to help get out as much of the carbon thats in those ports out as you can, also there is a port on the side of the carb that the egr sends the exhaust back into the carb through [the sub-egr] you want to make sure it's not clogged with carbon, same goes for the port that leads back to the cylinder head. also make sure that you test the egr so you know it functions correctly, inspect the emissions vacuum hoses for any leaks or damage, and if you have a good wide-band gauge, you can set the AFR via the mixture adjustment screw on the carb, but don't mess with it unless you have a good wide-band [I used the innovate LC2], thats how I got my truck to pass CA smog, I made sure the truck was running at a good 14.7-15.0 on my wide-band, after it was all running good, I took the gauge out, put in a new stock o2 sensor and she passed smog on the first try, nox was a bit high [but it was still within limits for a pass], and after the test I discovered one of my vacuum lines was disconnected, the one for the HAI hot air intake flapper, so check your vacuum lines for sure maybe even go to a parts store and replace them all with new stuff just to be on the safe side do 1 at a time tho, it shouldn't cost much they sell it by the foot, also try running 89 octane gasoline CA gas is not what it was in the 80's.
I have an o2 sensor in it cuz the manifold came off an 85. Don't know if it's a wide band I was going to replace the vacume lines also. Gonna clean out the egr also. Go for a retest tomorrow. Anything else anyone can think of that might help?
Well after further inspection, I pulled off the egr and found it was stuck open. Cleaned it and then ports out and it seems to be doing fine. gonna try again tomorrow.
Good luck. If you can fix an A/F meter in your truck and hook it up to the O2 sensor, that would be handy to monitor your engine tune.
Where might I find one of thoes?
Got it smoged again, failed nox at 15mph
Depending on the O2 sensor you'll need one that will work with it (narrow band or wide band). Ebay is a good place to start. It's a good diagnostic tool for air/fuel mixture and can also help you maintain fuel economy while driving (not any good to monitor NOx though).
Damn. What were your NOx readings this time around?
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Here they are
Got another problem I have lost 3rd-4th gear! Never ducking ends with these things!
It's dropped a fair bit but still need to get another 600+ ppm down from the NOx reading. What are your plugs like? Have you changed fuel (gone up to a higher octane fuel like 98+)? You can try decarbing the engine by taking the air filter lid off it and spraying water with a trigger pump down the throat of the carb while running it with the throttle open. This won't kill it and you should be able to hear some exhaust 'crackle' when the carbon build up is burning off.
I'll pull them later and put up a pic. Thinking I'm going to just take it to the shop that rebut the carb and have them make it pass smog
what is your idle speed set at, you want to keep it around 650-750 if the truck runs on, when you turn it off, you will want it on the lower side of spec, also check your timing and make sure your firing order is correctly set at 1-3-4-2, change your oil and filter right before the test, you can also sort of cheat a little on the test by keeping your heater set to the highest side of the heat, and leave the blower on low, when was the last time you had the coolant flushed out? you can run straight distilled water to draw the heat out better, or use flush to clean the cooling system or have a shop flush it out, there could be blockage in the system, you should probably change your thermostat with a brand new one, also, if you have not done it yet, pull the sub egr off of the carb and clean the passage out completely if you have not yet done this already.
Higher octane fuel will burn richer in effect lowering nox a little, but it might raise your HC numbers. Are you running a new o2 sensor, I'd say just swap it to be on the safe side, they have a 60k mile life span on average [ I'm not sure if they had 02 sensors on the early trucks if not disregard it], spark plugs around 30k miles, you may need to chase the threads on the manifold a few times with a thread tap tool, and for sure use anti-seize on the threads of the new one, also spark plugs and there gap should be checked, also check vale lash clearance is set right, new heads need to be adjusted correctly after cam break in. also what comes to mind is cap/rotor/plug, also not really related to nox, I changed my oil and filter the same day I took my truck in for smog.
Usually NOX is the egr on these motors, but I have also seen high nox on smogs caused by; an improper adjusted or bad TPS; old/worn/wrong gap spark plugs or wires; ignition timing advanced too far or wrong firing order; bad or worn radiator fan clutch; loose accessory drive belts, clogged cooling system,and or bad catalytic converter, it could be other things as well, these are just some good areas to work on.
He's running neanderthal tech - carb and ICM distributor pre '85. I can only think of lower temp rated plugs and a new coil for a cleaner burn. If only there was a way of testing the NOx in real time while altering the ignition timing without the smog station headaches...
The truck is running cooler than it ever has, barely gets past the second white hash mark. I did notice my coil getting really warm not sure it's supposed to. I guess I Chang that out next. I set ever thing to the sicker under my hood. Timing is set at 7* btdc I set my valve lash to .006 intake and .010 exhaust. Had to was new non jetvalve head and up arp head studs and new cooling everything. I also had some fuel additive too. New fuel filter also.
What plugs should I run? Also was maybe thing msd coil?
Maybe try a 6ES plug (normal is 5). I wouldn't worry too much about the MSD stuff. A lot of it seems to be marketing and not much else. Get a Diamond brand/OEM transformer type coil for a replacement from ebay. At least a 25% improvement over the oil filled coil - it should get a cleaner burn and either restore or make a little mid to top end power + aid fuel economy.
I'm pretty sure they are what I am running in it now, found 2 more new sets of 4 of them in the back. got to fix other stuff before I get back to this. Tranny rebulild😕
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