I failed an inspection yesterday, check sig for car details, upgrades, etc.
In my area, for OBD1, they run on a dyno at 15mph and 25mph for at least 3 tests. Tests are for HC(ppm),CO(%),CO2(%),O2(%),Nox(ppm)
HC and CO(%) came WAY under, HC standard 153- reading 48, CO(%) standard 0.86 reading 0.01, CO2(%) and O2(%) have no standard on my report, nor pass or fail. Nox was near 4x over limit, standard at 25mph=1123, reading 4454. standard at 15mph 1242, reading 4272.
I am thinking it runs lean with stock ecu, but isnt this extreme?
Realisticly, I am still a few weeks from an s200 and tuning, but my sticker is out NOW, and the Barney Fifes in my town have nothing better to do than harrass a loud red civic.
I changed the TB same time I changed plugs and wires, I suspect the TB may be different enough to blame the high idle on- 900 is about as low as it gets, 11-1300 depending on whats turned on. A VERY slight noticeable drop if I unplug the IAC. I have tried with the TB coolant bypass, and without- seems the same to me.
A local mechanic installed all upgrades but the TB, CAI,plugs and wires, it idled around 700 before I did those.
Now some questions...
Would a new or added Cat. convertor change it that much?
This car never had an EGR system. That I can tell.
I suspect the A/F is off due to upgrades and stock ECU, maybe timeing as well...
If I go back to stock TB, where the idle was lower and less erretic, how much difference could that make?
I have sprayed Berrymans at all the areas I thought might have a leak, no sign of one.
The Comp Cam is near the same as Honda, except more duration? ( agressive slope?)
Do you think I have added enough upgrades to warrant colder plugs?
After upgrades, the only real change that I see is no coolant running through the S2 intake, is this important? BTW, I thought this may have been a EGR component untill i tasted the coolant, stop laughing.
If you think I missed something, please hollar.
OB

 

It's probably that cat, if your pipes are so set up so you can bolt a stock cat on, do that. Also you should have the heat shields in place to keep the cat hot so it can destroy NOx effectively.

Course it would be cheap and easy to put your stock TB back on to eliminate any doubt about that.

The mixture should be OK if you have the O2 sensor in place and it's not setting the CEL, the ECU has the mixture under control. You could make it run a lot richer by disconnecting the vacuum line to the fuel pressure regulator, but that's probably just going to blow the CO limit and make the ECU unhappy.