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1994 Accord failed NOX smog check

10-25-2011, 02:06 PM
I just got a 94 accord EX and took it to get the California smog check. It passes all the test except the NOX at 25 MPH. It reads 1460 and the max is 511. I have done many things to it including replacing a new CAT, O2 sensor, and used EGR valve and frequency solenoid and valve. I am now stuck with a car that can't pass the nox portion of the smog test. Any help is greatly appreciated!!!

10-26-2011, 04:59 PM
Did you check that the EGR pipe and passage were clear all the way down to the exhaust and intake while the valve was off? Sometimes they are partially or completely plugged down out of view...

10-26-2011, 05:18 PM
I cleaned the EGR ports yesterday and yes it was totally clogged up. Will take it back to get it tested again tomorrow. Hopefully it will work this time, thanks so much for your reply!!! Do you think I need to check anything else before taking it in?

10-27-2011, 12:01 PM
Make sure all the vac lines to EGR, PCV, FPR, etc are intact. Sucking air at low rpm under load can make NOx high, but I'd think they'd see it on the 15 mph check even worse if that were the case. Worth a look though.

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