Did not pass smog check. Help!
Thread Starter
TECH Apprentice
Joined: Oct 2010
Posts: 341
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Did not pass smog check. Help! OK so I pass mainly everything except for the 15 mph smog test, the car
failed on NOX or in other words nitrogen oxide. NOX on max is 483 to pass and
the car got a score of 550 which is not too far above 483. So it failed and now
I have to figure out what could it be. It did pass NOX on the 25 mph
test with a score of 406. So the egr valve must be opening at 25 mph right?
Last time (last week before smog test) I tested the egr valve with a pressure
pump, it would not hold pressure, nothing not even 5 psi, but I guess at 25 mph
it opened and got enough suction to open and it passed.
Please help? Im positive the egr valve passage is not clogged or both test on
NOX would have failed so the lines are not clogged right?
Could it be the EGR Diaphragh is not holding pressure?
failed on NOX or in other words nitrogen oxide. NOX on max is 483 to pass and
the car got a score of 550 which is not too far above 483. So it failed and now
I have to figure out what could it be. It did pass NOX on the 25 mph
test with a score of 406. So the egr valve must be opening at 25 mph right?
Last time (last week before smog test) I tested the egr valve with a pressure
pump, it would not hold pressure, nothing not even 5 psi, but I guess at 25 mph
it opened and got enough suction to open and it passed.
Please help? Im positive the egr valve passage is not clogged or both test on
NOX would have failed so the lines are not clogged right?
Could it be the EGR Diaphragh is not holding pressure?
Last edited by 323steel36; Aug 17, 2011 at 01:28 AM.
Staging Lane
Joined: Jul 2010
Posts: 79
Likes: 0
From: Aurora, Colorado
my truck has no cat and failed horribly. 5 gallons of e 85 out of 18 in the tank and blew clean. the e85 leans it out. dont beat on it till after you burn all of it off. works great. id say for a full tanke run 3-4 gallons and get it nice and hot before you drive there. it will pass
Like you mentioned it could be EGR, have you tried to replace it?
NOX levels beening high is due to high combustion temperatures. Since we run higher compression we creat more heat, so try running higher octane it will reduce it a bit.
NOX levels beening high is due to high combustion temperatures. Since we run higher compression we creat more heat, so try running higher octane it will reduce it a bit.
Thread Starter
TECH Apprentice
Joined: Oct 2010
Posts: 341
Likes: 0
Thanks everyone, so I finally decided to replace the egr valve and went to retake the smog test and it passed by a long shot not to mention the car feels much better when Im driving. It lower NOX by alot thats cool im happy now. Thanks to all that helped.
