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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: kurtdirt1 on January 04, 2010, 07:57:19 pm
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So I failed smog today (high nox) Troubleshooted the egr and my passages are clogged. What should I do now? The engine is new but I re-used the same intake. Is there some kind of solvent I could use or would I be better off just getting an intake manifold from the wrecking yard.
Whatever makes more sense financially is what I'm looking for. I'm on unemployment atm so what would you guys do?
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should be able to hit the passages with some carb cleaner and then blow it out with air or vacuum it out.
If you do use compressed air, please wear safety glasses and keep your face away.
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should be able to hit the passages with some carb cleaner and then blow it out with air or vacuum it out.
If you do use compressed air, please wear safety glasses and keep your face away.
Okay, so I picked up a blower nozzle for my air compressor along with a can of B12 Chemtool. I got some eye protection around my house somewhere.
Anybody ever had to deal with this before? It seems that the passages make a 90deg turn about 2.5" in. Where exactly do the passages enter into the manifold? Do they enter in the middle of the intake where there's a hole between the left and right side of the intake?
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Use a screwdriver and poke a hole in the carbon chunk. Take a shop vac and suck it out. Break the pieces off and suck them all out as best as you can. Once you put it back together you'll know if it's flowing by lifting up on the diaphragm on the egr valve as it should stall the engine. If it still doesn't flow then the passages through the head may be carboned up too.
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Okay so today I cleaned out the passages the best I could with B12 Chemtool and and Air Compressor. Man it was really CLOGGED up, big ole chunks were coming out. I'm not sure if I got it all out but I passed smog today with flying colors so it must be good enough.
My nox readings yesterday were 1400/1300 and today they were 400/400. So if anybody is passing on all parts but the nox is too high, check your egr and if your egr is fine, clean out the passages.
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Good deal. :) I would have suggested the shop vac but sometimes the air compressor is easier. Also, if the test is a two-speed one, you probably need to run it in a lower gear than normal so the engine's not lugging. That'll shoot that NOx reading through the roof!
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Yeah it was a two speed test, 15 and 25 I believe. It passed with flying colors so now I know to test out the egr system before I smog another one of these trucks again.
The truck ran great so I didn't even suspect anything wrong. I swapped in a new engine about a month ago and the manifold was about the only thing that I didn't check out before I hooked up. Lesson learned lol ;D