Stupid emissions. Here are my results:
15 mph: 25 mph:
Limit Reading: Limit: Reading:
HC 152 38 147 135
CO .85 .09 .82 .16
NOx 1186 2435 1072 1969


As you can see, I failed NOx at both 15mph and 25mph, and my HC was rather high at 25mph. The car was fully warmed up befor hand. I guess that could be bad for NOx? I know higher compression results in more NOx. What helps to reduce NOx? I know the reduction part of a 3 way cat helps, I really hope thats not it. my tune up items are fine btw. It is also worth noting that I am low on power (dynoed at 121 hp with I/H/E). I dont know if these are related. Could a clogged injector cause any of this? With the engine cooler would my NOx be lower? I have all my emissions equiptment intact and my timing is around 15, would knocking my timing back to like 11 or 12 help? TIA

Check your EGR if you haven't already. My new (to me) 92 SE-R failed Texas emissions for NOX until I cleaned the clogged EGR pinhole. I also verified the operation of the BPT and EGR with a vacuum tester. I understand that retarding the timing may also help with NOX. From my research, I gathered that most things you do to reduce other emissions will raise NOX and vice-versa(ie. leaner=more NOX, less HC & CO BUT richer=more HC & CO but less NOX).

BTW when I passed the second test my HC count raised to exactly the limit. IMO, the worst thing about emissions tests is not being able to test/tune yourself.

Ben
92 SE-R

Ok, just checked some vacums and may have found the problem. There are two discs in the back of the engine bay near the firewall. The left one being the egr, and the right one I guess is some sort of accuator motor or something. Im getting no vacuum after that motor (between the egr and the motor thingie), but do get a vacuum befor it. I guess that needs to be replaced?

The left "disk" is the EGR and the right one is the EGR-BPT(BPT). The BPT controls the EGR based on vacuum and exhaust pressure. Remove both valves but leave them attached to one another. Try applying pressure(I just blew into it) to the bottom inlet on the BPT while applying vacuum on the top inlet(the one not connected to the EGR). I think this the correct set of circumstances to cause the EGR to open. Someone please correct me if this sounds incorrect.

Hope this helps,
Ben
92 SE-R

I have had 2 sr20 powered cars fail NOX. Both where the Cat. I asked the tester for some in put, he stated point blank if it is very hot out more cars fail NOX. He has literally turned people away on the HOT HUMID days. Small NOX failures he stated usually are EGR related 1.00-3.00 anything higher from his experience has been a bad cat.


Good Luck

It was very hot today, in the 90's. Im pretty sure my B.P.T valve is bad, anyone know how much a new one costs? I think ill replace that and go on a cooler day and see if that works.