Emissions GA high NOx

I failed emissions in my turbo Miata yesterday. It passed the 30mph roller test part, but failed the 15mph test with high NOx.

30mph NOx 1004ppm passed, 15mph NOx 2467ppm needed to be 1242 or less

From what I can tell the EGR system should take care of the NOx at the lower speed. My EGR is disconnected, cross over tube is gone. My question is what can I do to pass emissions? I have one re-test, Oh great mind of GRM..... WWGRMD?

Hook up the EGR?

Otherwise, exhaust leaks before the catalyst will skyrocket NOx. Colder plugs and retarding timing will help keep combustion temps down and will also reduce NOx. A new catalyst may be able to mask the lack of EGR, but probably not enough.

With those kind of numbers, is it safe to assume you don't have a catalyst?

IF you do, it's a tad on the lean side. Intake leak first, exhaust second, lean running third.

Other than that, what are your HC and CO numbers- that will tell you if you can make an obvious adjustment.

Your screwed...it's junk now. I'll give you scrap price for it.

Cat is on, unknown condition.... HC 57 - 69,
CO% 0.00 - 0,01,
CO+CO2% 12.2 - 14.3

first number is at 25mph second is at 15mph The car has a Electromotive TEC2 for engine management. The turbo manifold has no provisions for an EGR tube. I'm not opposed to putting a new cat on it.

In reply to alfadriver:

At 12lbs of boost it runs rich. The guys at Balanced Performance did the tune in 2001ish. The boost gauge pulls 20 in hg at idle. The car has been converted to a map sensor.

Are you running with an O2 sensor? I know the TEC2 is capable. You are running pretty lean, basically- with almost no CO. Just running with the basic feedback that the TEC2 can do, you will probably pass.

Since your NOx standard is over 1000ppm, is the HC standard like that, too? And the CO close to 1%?

Again, even a marginal cat running with basic feedback will do wonders with what you have. Or just run it richer at those points- target 14.6 on gas, 14.3 on E10.

I'm running an O2 sensor. The HC ppm allowed at 25mph 155ppm, 15mph 159ppm. The CO% max .89 I might need to check my fuel pressure under load. I think its time to break out the wide band O2 sensor. I'm running E10 premium btw. I will have to see if I have the software to change the tune.

Three bottles of Iso-Heet with a quarter tank of premium?

In reply to slefain: I'm thinking colder plugs, chuck some E85 (2gallons to my 1/4 tank) in her and see..... I can see if I have a new O2 sensor in my pile too.

Not sure on the Iso-Heet.

http://www.importtuner.com/tech/impp_1109_how_to_cheat_an_emissions_test/viewall.html

Here is a picture of the victim.....

and

clownkiller wrote: I'm running an O2 sensor. The HC ppm allowed at 25mph 155ppm, 15mph 159ppm. The CO% max .89 I might need to check my fuel pressure under load. I think its time to break out the wide band O2 sensor. I'm running E10 premium btw. I will have to see if I have the software to change the tune.

What is the sensor doing during the testing? So if you find the software to tune it (and I hope it's the WinTec2), see if you can log the O2 sensor, and make sure that it's being used for feeback at these conditions. Voltage should target .46 V or so- which is a nice an unstable point which will force the a/f to switch back and forth- and that will result in good emissions.

I have WinTec2, don't know if it work yet..Thanks for the help.

Even if you had an EGR fitting on the manifold, the valve requires a fairly complex control algorith, and the output affects your fueling because MAP no longer tells you how much O2 is in the manifold since some of that pressure is exhaust gas instead of normal air. I don't know of any aftermarket ECUs that will control EGR.

I would look at how much timing it's running the test zones vs what a stock ECU does.

clownkiller wrote: I have WinTec2, don't know if it work yet..Thanks for the help.

sounds like you need boswell...

In reply to AngryCorvair: It does need a Megasquirt, this car is a great driver. I'm trying to pull emissions for when I sell it. I have a turbo Metro and a turbo 510 that needs a Boswell.

I called Electromotive, well without a copy of the present tune, I can't change anything. I can't download the present tune, just load a new tune into it. Looks like I'll retard the timing with the pickup, colder plugs, chuck some E85 (2gallons to my 1/4 tank) in her and see..... I can see if I have a new O2 sensor in my pile too.

Thanks again

Retarding the timing should do it. That's how my SHO passed NOX with no cats. Just barely though.

Passed emissions today. I pounded the NOx in half on the 15 and 30 mph test. I put in a new O2 sensor, pulled the intake line off the turbo, and put in really cold spark plugs. Thanks again.

Future reference: register it in my name, dummy. Or at the cabin(?)

It opens up the whole of ATL when I sell it. The craigs ad can now say current emissions, instead of "needs a tune", good luck sucker.

Right right. Gotcha.

Trade for Integra? It's got 4 seats!

Trade for a 4 door integra? 4 seats AND 4 doors!