Had the car emissions tested in january.

Failed due to NOx emissions. 2.29 grams/mile limit at 2.00

Other measurements are HC .047 g/mile (limit .080) and CO 6.82 g/mile (limit: 12.00)

Rebuilt the engine. EGR system is clean, new plugs, wires,cap/rotor Vtec heads, gaskets vacuum lines, cleaned everything. No check engine lights, timed within spec.

Retest fail.

NOx emissions now at 2.39 g/mile (up) (fail)
CO 19.83 g/mile (up, fail)
HC 0.72 g/mile (up, pass)

The VSS is currently inoperable. Speedometer, cruise, etc not working.
The IACV is busted. Engine revs at idle between 1000-1500 RPMS up and down. Unplug the valve, the idle goes back to normal.

The engine has no power over about 3500 RPMS at WOT.
Low end operation is fine, pulls hard to 3500 and then dies. I suspect the bunk VSS is preventing the High lift cam from engaging.

Inputs? All the numbers are up.

 

Soldered a new connector into the harness for the VSS. Speedometer is now working.

Anybody have any input?

 

NOx is created by a combination of high heat and high pressure. A working EGR system reduces this to a pretty good extent and the cat will help clean up the rest.
Verify base timing is set correctly. Do you have O2 readings?

 

New catalytic converter (magnaflow) and O2 sensor (denso).

Passing CO now, better than first test. NOx doubled to 4.12 grams/mile (up from 2.39, limit 2.00) still failing

Now failing HC. (1.10 grams/mile) limit 0.80

So I've gone from failing Nox, to failing Nox and CO, and now failing NOx and HC.

Timing is set correctly. New cap/rotor/plugs/wires.
Rebuilt heads. PCV valve appears to be working correctly.

 

When a new cat is installed you will need to put a few miles on it before testing.
A new cat will almost always fail if you install it and then test it freshly installed. The cat acts like a sponge, it will absorb and release the various gases while stripping and catalyzing.
Was the testing done shortly after the install of the new cat? You may want to try to put a few more miles on the new components before going for a test.

Did the VSS fix the 3500rpm issue?

When you apply vacuum to the EGR valve at idle, does the engine die?

 

Yes, EGR kills the engine quite quickly. I installed the cat on friday and have only driven about 100 miles since then.

VSS fixed the 3500 RPM issue, lack of a speed signal was causing the ECU to disable the vtec crossover.

I found the drive graphs this time and attached it as a .PDF
It appears that NOx and HCs spike under load. If the cat being new isn't an issue (which would make sense, readings doubled from what the OE, 300,000 mile drive for a year burning coolant cat was doing) I have a couple other theories at to what the problem might be.

My IACV is toasted and the car idles at 1100 RPM and bounces off the freeway (unplug it and the idle is normal). Possibly a lean misfire due to a resulting vacuum leak.

The other X factor is oxygen sensor placement. The car had the F22B2 stock manifold and O2 sensor placement in the merge point for all three primaries. With the megan headers I installed the O2 now feeds solely off the #3 cylinders primary. From my understanding of your average intake manifold design the cylinders farthest from the throttle tend to get a little less air and the ones closer tend to get a little more.

I was thinking it might be the case that the a/f ratio is off, as the exhaust content of 3 of the cylinders is not being monitored.

 

That should be fixed.
Correct. Rather than the sum of all the cylinders being used to fine tune the engine, the ECU is now only seeing one cylinder. If cylinder #3 is out of tune the whole engine will be out of tune. Can you replace your stock manifold for testing? I do not care for headers that only sample from one primary. The O2 should be placed down stream either at or after the collector.
A quality header company would have supplied an extension to allow the O2 sensor to be placed in the correct position. If this is Megans way of cutting costs, its foolish. I prefer CARB/EO headers for this very reason, they are made so compliance and drive-ability are maintained.

 

My stock manifold is cracked in three places and currently somewhere in an arizona recycling facility. The megan headers have a bung on the collector right in front of the cat, so all I have to do to move the sensor is grab some connectors and make an extension for the wires, I have all the supplies. Will take care of this and update when it's done.

 

To bring closure so that others may learn:

Passed emissions today.

.65 HC
1.52 NOx
3.80 CO

Plugs confirmed that cylinders were running richer/leaner from 1 to 4
Moved O2 sensor, replaced IACV and reset base Idle to ~500 RPM. All gravy.

 

Awesome. It's sad that 'Sir, you've passed' is one of the most stress relieving comments any man may hear in his lifetime.