Hey all
This post is for a friend, its a ford (sorry dont yell) but I figure smog is the same on all cars. Anyway he just got he car smog tested and he failed the NO(PPM) his reading was at 15 MPH was 2000 and the max is 2000 so he passed that one, however at 25 MPH it was 2178 and the max is 1950 so he failed that test. The smog shop wanted about 200 bones to T/S the problem. Can someone please help me on what to replace?? there are no error codes on his car, the check engine light works but is not lit. I am thinking its the EGR valve, however he repalced it 2 years ok to pass smog. any ideas..
Thanks and please dont throw rocks at me because its a ford, I would never dirve it anyway, I would take a bus or taxi first!!!!

Thanks in advance
Brad

 

Your thinking may be right. Check the EGR. Don't only look at the valve, but check the passages to and from it. If its a newer Ford, it should have a digital EGR, so make sure it is getting signals.

 

Another thought in addition to the EGR suggestion.....

If he's got the ignition advanced beyond stock specs, put it back. If it's at stock specs retard it another 4-6 degrees and try again.

NOx happens at elevated combustion temps. Elevated combustions temps happen with over-advanced timing. I've dialed them back so far the engine barely runs. Runs bad, passes good. Crazyest thing you ever saw. You would burn TONS of gas driving it around like that (not to mention no power and possible overheating) but the sniffer says "A-OK, buddy!"