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I passed all tests but the nox test. 650 max and I had around 1200 . I have a new cat, and I am in the procces of doing the tests in the FSM. I am almost done and my car has passed all tests so far, like the diverter/ air switching from exhaust to cat after closed loop. I have changed the oil and I was wondering if any one had any tips on what to check? EGR valve checks out and the openings were not looking plugged.
When I lift the EGR the engine stumbles a little. It is running better than it ever has. New wires , but high Nox.
Thanks in advance.
Also - and I don't know if this is the case - but if the car has sat for a while and the fuel in the tank is old, it will cause problems in the smog test via improper combustion. I had this happen myself after I worked on the car a few years back to fix a nagging clutch slave issue, and the car failed NOx. Put new fuel in the tank, re-tested, and it was 1/3 of the value in the prior test. Blew my mind.
NOx is produced by high combustion temps and that's what the EGR is for, so I would investigate that further. Not a bad idea to get some fresh fuel in the tank, and there are fuel additives designed specifically for passing smog tests as well, not sure if they help NOx emissions but hopefully you will not need those anyway. Also take the car for a good rip or highway run before testing, get it nice and hot and make sure the tailpipe emissions are burned to a crisp. A hotter engine produces less emissions and to my knowledge this is the main reason why the fan temps are programmed so high.
I took it apart and noticed alot of carbon buildup and when I did the open egr test while idling I had very little difference in idle. I am going to try and clean egr ports and areas because I know they are dirty. Here are my reference pics for the manifold channel, and then use some kind of brush to clean the tube openings.Hope to not remove the lower intake but I will if I have to I guess.
Thanks for the tips. This has been a great read in case someone else needs it https://tech.corvettecentral.com/201...egr-diagnosis/
If you are that far, check if your injectors are Multecs or not. If they are, toss them. If not, send them to FIC for cleaning and testing so you can see what it was and what it is.
Yes the 85 only has 1 on the left bank. While I am posting today I took the plenum off for cleaning of the air passaged. I could not even see them but now they are open here is a pic. Harbour Freight has a great pipe cleaning kit for 7.00 or so.
Ca smog help please. Does Cat need break in?
