Thread: Calling all engine experts - Smog from hell

I am desperate. I am a broken man. I want to set the NX on fire.

Sooo, I need to pass smog and an overall visual inspection (no turbo!). I removed the turbo, and set out to smog it. Here is a quick list of the first setup:

-SR20VE
-Brand new CAT, used 5 days
-259cc DE injectors (with crappy variable resistance)
-Nismotronic
-4.9 LSU Wideband, narrowband input to ECU

Here are the first round results (failed ones circled). Idle and fast idle.


Corrections made:
-As you can see, lambda was way off. After consulting this forum, people pointed out that the sensors tend to get unstable as they get too hot from running near a turbo. I ordered a new LSU 4.9 sensor and installed it. I instantly noticed a much smoother AFR, with way less swinging.

-Another lambda related issue, was a leaky exhaust. I rewelded the cracked section.

-Midway trough all this, one injector died. Infinite resistance. I swap in decapped Subaru 750cc injectors, and retune the car. Re-test!

Here is round two:


F#%k, now I'm confused. Lambda is perfect, but all other stuff have gotten way worse. Thinking the injectors did it, i did the following corrections.

-Top feed fuel rail conversion

-Bosch EV14 1000cc injectors

-Adjustable fuel pressure regulator, set to 3.5Bar base fuel pressure

At this point, I'm feeling pretty confident. Re-test

Round three:


Well, it got slightly better. But it's still way off from what it should be. The inspector revved the shit out of it to get the fast idle to pass. You can hear a faint misfire? in the exhaust note, especially when revving, but nothing is seen on the lambda.

List of random stuff replaced this year:
-Headgasket
-PCV valve and orings
-Distributor swapped for lower mileage
-Spark plug wires

So now I have spent >700$ trying to get this heap to pass. I am in dire need of some directions. I will post the tune/screencaps of maps/logs soon. Sorry for such an unstructured thread...

Placeholder for pics:
Idle is 900rpm, 15* BTCD with throttle closed. When revving without load, it gets 34* BTCD all the way from 2000-3800rpm.

Several years back I had an issue getting my '91 to pass inspection. I talked with the mechanic, and he said a lot of the issues are from carbon and other buildup inside the engine. He ran some Seafoam Motor Treatment through the air intake, it produced a large cloud of white smoke, let it sit for a bit, then started it up after about 10 minutes and revved until the smoke cleared up, ran the emissions test again, and instant pass. Since then I've done the same thing from time to time on my cars, remove the brake booster line and drizzle this into the intake manifold, cleans up the intake valves and cleans up the buildup in there.

I don't know if you have this product in your area, but there may be something similar available that will do the same thing.

Run spark gap as big as you can, lowest octane rating you can get, a well heated (1st gear on streets , 3rd gear on hwy) cruise make sure if when you get there if there is a big line of cars in front of you keep reving your engine few rpms to keep things nice and hot so the cat can work at its optimum , and retard dizzy few °s ,some say a fresh oil change can reduce pollutions as well wroks for me every time even on boosted cars

looks like aggressive timing causing your slightly aggressive hc. do you have a log of the test as it was ran?

I wish it were as simple as that. Had the engine apart a few months back, manually cleaned the combustion chamber and intake manifold. It was spotless when I was done, way better than any solvent would have gotten it. Thanks for the suggestion though..

Currently using lower ignition map values than when I tested last year, unfortunately not the case . We revved it for a solid few minutes with the tester, it was HOT! You could hear popping in the exhaust, seems like a misfire.


Again, that is not aggressiv timing, especially with E85. See logs further down.
So, here is the timing map.

Very conservative, especially with E85. Lower compression than stock too due to the metal HG, so that alone would bump it up a few degrees. Smog is happening in the 37'deg area. 15 with throttle closed.
Lets get to actual data. Here is a screenshot from when it feels like a misfire. TCD+log at bottom of this post.

Feels like power loss, targeting Lambda 1.00, you can feel it in the car all the way from 2800-4000rpm. See the AFR, it swings pretty exessively. It has done this for a year now, no matter what injectors are in use.

TCD: https://www.dropbox.com/s/gnmyfob0gwalw2d/20VE%20Summer%20E85%20v1.51%20ID1000.tcd?dl=0
Log: https://www.dropbox.com/s/vzy7j690icakbxg/MisfireSteadyThrottle.TCL?dl=0

For those without Nismotronic, Here is youtube link with the misfire part: https://youtu.be/8zSGLfXUzz4

Some things to note.
-AFR offset is not perfect in Nismotronic, but no need, since I'm using narrowband.
-Knock detection is disabled, using 2$ unreliable ebay knock sensor, see voltage in log!
-Fuel map is rough, due to only a few minutes of tuning. Closed loop handles it though. It is only smog checked at idle/fast idle, so no need for a perfect map.

Oh, and before all this logging, I changed the oil and sparkplugs. Here is what the old sparkplugs looked like.


Same sparkplugs last year netted me this smog result (they were my N/A smog sparkplugs)

Another day, another test

Today I went to a local garage and borrowed their smog testing machine, instead of heading to the official inspection place.

I tried to lower the ignition map.
-Instead of 15*deg idle, i tried 7-10*, no change.
-Instead of 37*deg fast idle, i tried 24-34*, no change
-Instead of 900rpm idle, i tried 750. no change
This was with brand new NGK BKR6EY sparkplugs, only used for 2h.

It still gives me 220 HC and 0.7-1.3% CO.

Oh, and @zeneffect I cleaned up all battery terminals and alt terminals, rock solid 13.89V for the whole test.

My main suspects at this stage
-ECU not giving even pulsewidth length at all channels. Maybe check this with oscilloscope
-ECU not providing spark correctly. Maybe throw on COP conversion?
-Engine not mechanically OK
-Valves leaking?

If you put on a MSD ignition with coil it would clear up that mess

Also aftermarket cats are usually the issue oem cat for the win

OK, you've got high HC, you've replaced the O2 sensor, and you're hearing faint misfire in the exhaust. High HC is from unburnt fuel, sounds like the fuel may be igniting while in the exhaust system?

There may be a vacuum leak somewhere, unmetered air is getting in that the ECU doesn't know about, messing with the mixture.