We are going in for another test Monday, how far do I need to retard timing on the MS to see a reduction in NOx. Unfortunately I don't have a way to test this and so far none of the emissions guys will let me log on the dyno.

Any thoughts?

 

The hotter, the cleaner it burns. I'd swap the old t-stat back in for the retest. Also, a couple of bottles of heet fuel additive have helped me pass NOx in the past. At $2/ea it's cheap insurance on top of the timing retune.

If all else fails pm me for the barrio deal.

 

I thought the Issue was because to was a bit to lean, and therefore to hot already. At this point I'm up for almost anything considering I want to drive my car, and I'm lost on the timing thing. I would think I need to retard it some, but I have no idea how far, and no way to test it.

 

First off I failed again, but thanks to Sprayed it much better. Its like I'm being teased, and thats something I'm not a fan of.

here are the this mornings results.

I failed again, plus the guy tried to fail me for not having power steering on an OEM power steering equipped car. Luckily one of the other guys said hey miata don't come with power steering. Thats the only good thing that happen.

So here's the deal, I failed NOx low and high.

High NOx Standard 1179 mine 1310
Low NOx Standard 1304 mine 2082.

All Passed on High Speed

High Speed 25 mph at 2207 RPM
HC PPM Standard (160) my reading (65) pass
CO% Standard (0.90 my) reading (.84) pass - very close
CO2% my reading 12.8 no standard listed nor pass/fail
O2% my reading 1.7 no standard listed nor pass/fail
NOx ppm Standard (1179) my reading (495)fail
Dilution% standard >6 my reading (13.6) no pass/fail

My issue is at low speed

Low Speed 15 mph at 2024 RPM
HC PPM Standard (166) my reading (94) pass
CO% Standard (0.93 my) reading (1.62) FAIL
CO2% my reading 12.0no standard listed nor pass/fail
O2% my reading 2.3 no standard listed nor pass/fail
NOx ppm Standard (1304) my reading (516) pass
Dilution% standard >6 my reading (13.7) no pass/fail

Ok, I think I might be able to work with this, but what has surprised me is that all three test were taken at different RPM's. That seems to make tuning for emissions difficult at best unless you consistently hit 14.7, and I don't.

Its going back in after work, I hope to be back to driving my miata Tuesday.

 

At least they give you a detailed readout. I failed my first smog attempt today as well. Passed NOx but failed HC and CO. They tested it four times. By the end my NOx was rising but still within passing, and my HC had risen further, but my CO had dropped to passing... I think it was hot enough by the end that heat soak helped lean it out a bit and that brought down the CO. Attempt number 2 tomorrow after leaning it out a bit more in some spots. Any one have a recommendation on how far to retard timing? Like take 1 or two degrees out of the whole DIY base map?

 

To bad your not in Cali. $300 dollars and no headaches

 

this might help you fine tune for emissions testing:

 

I passed, and I believe the Heet helped with the initial reinspection, and my car is running much better.

y8, is the number at the bottom of the chart voltage from an O2 sensor?

 

this better?



basically there's a very narrow region where you are minimizing both CO and NOx right around stoichiometric.

 

Thanks,

It looks like I have another year to get everything dialed, but this time with boost. Considering the RPM, and the size of the turbo I'll be using other than possible restriction in the exhaust, I wouldn't think the turbo will effect emissions at all. Since everything tested is below 3000rpms.

 

+1 and sensible timing. I had done nothing to idle and 3000rpm (that is where they test here) and just set EGO to hunt 14.7 with a 10% correction bandwidth or something. Passed without further fiddling.