Failed Inspection Sniff Test - 4 Times! Help!

**Treibenschnell** · 10-28-2005, 04:53 PM

Okay... here's the situation... I've now failed the inspection sniff test three times. This is getting ridiculous...

Here's what we know so far:

Replaced spark plugs
Replaced spark plug wires
Replaced O2 sensor
Set timing back to 10 degrees
Using a FM high flow cat (that does work!)
Using 87/89 octane gas from 7/11

Here are the numbers:

First Test -

High Speed Emissions Results (25 mph)
--------------------------Standard ------Current------ Result
HC (PPM) -------------------160----------- 12--------- PASS
CO (%) ---------------------.90----------- .02--------- PASS
CO2 (%) ----------------------------------14.4
O2 (%) ------------------------------------1.0
NOx (PPM) ------------------1179--------- 2340-------- FAIL
Dilution (%) ------------------>6---------- 14.4

Low Speed Emissions Results (15 mph)
--------------------------Standard -------Current ------Result
HC (PPM) -------------------166------------18--------- PASS
CO (%) ---------------------.93 ------------.03 --------PASS
CO2 (%) -----------------------------------14.2
O2 (%) -------------------------------------1.1
NOx (PPM) ------------------1304-----------2685--------FAIL

Second Test - Replaced Spark Plugs and Wires

High Speed Emissions Results (25 mph)
--------------------------Standard---------Current------Result
HC (PPM) -------------------160--------------107-------PASS
CO (%)----------------------.90--------------.38--------PASS
CO2 (%)--------------------------------------13.8
O2 (%)----------------------------------------1.4
NOx (PPM)------------------1179--------------1530-------FAIL
Dilution (%)------------------->6---------------14.2

Low Speed Emissions Results (15 mph)
--------------------------Standard----------Current------Result
HC (PPM)--------------------166--------------166--------PASS
CO (%)----------------------.93---------------.65--------PASS
CO2 (%)---------------------------------------13.4
O2 (%)-----------------------------------------1.6
NOx (PPM)-------------------1304-------------2382-------FAIL

Third Test - Replaced O2 Sensor

High Speed Emissions Results (25 mph)
--------------------------Standard-----------Current------Result
HC (PPM)-------------------160-----------------106-------PASS
CO (%)---------------------.90-----------------.23--------PASS
CO2 (%)----------------------------------------14.0
O2 (%)------------------------------------------1.3
NOx (PPM)------------------1179---------------1137-------PASS
Dilution (%)------------------>6-----------------14.2

Low Speed Emissions Results (15 mph)
--------------------------Standard------------Current------Result
HC (PPM)-------------------166-----------------136--------PASS
CO (%)---------------------.93-----------------.29---------PASS
CO2 (%)----------------------------------------14.0
O2 (%)------------------------------------------1.3
NOx (PPM)------------------1304---------------1726--------FAIL

___________

The first test was yesterday afternoon... the second was this afternoon at about 3pm. The third was at 5pm.

This morning I drove from Frisco to Texas Stadium to perhaps clear the cat of any contaminants. The cat and the car definetly were up to operating temp for the second and third test.

Perhaps pre-detonation? The inspection tech was very helpful but there was only so much he could do. Their mechanic walked over and offered his help at $79/hour. I politely said no thanks.

Do you fellas have any ideas? I'm at a loss here...

**Screamin'Screw** · 10-28-2005, 06:16 PM

Grab some of that guaranteed to pass emmissions stuff from AutoZone.

**Treibenschnell** · 10-28-2005, 07:38 PM

Originally Posted by Found this on the ::Batman:: board...

High NOx is usually the result of poor EGR action (applicable on '94+ Miatas only) and/or other causes of high peak combustion temperatures. The latter can be caused by glowing carbon deposits on the valves, head, or pistons, or by advanced timing, or by low octane gas. Try a Seafoam treatment ("carbon cleaning"). You could also take out a 2nd mortgage and try a tank of premium gas prior to your next smog check. High octane gas burns more slowly, and in combination with the correct timing (10° BTDC on a Miata) will result in somewhat lower peak temperatures.

Perhaps???

**Treibenschnell** · 10-28-2005, 08:47 PM

Just did the 'ol Seafoam treatment... and much to my dismay, the stuff came sputtering out of the header where the four pipes meet into one. Perhaps a problem?

**channelmaniac** · 10-28-2005, 09:11 PM

Time to get it welded...

**homerneedspeed** · 10-28-2005, 10:13 PM

my girlfriends 300zx failed for nox and i replaced the vacuum lines on the intake and it passed so i would check for vacuum leaks. also make shure they are using a fan to simulate road wind, if they don't nox increases with temprature so you could be failing due to cylinder head temprature . nox and co are related so a low co reading is almost always related to a high nox and a vacuum leak

**Treibenschnell** · 10-28-2005, 10:16 PM

They were using a fan on the front end...

**TurboDuane** · 10-28-2005, 10:22 PM

How fresh is your oil? Clean oil can make a big differance.

**Treibenschnell** · 10-28-2005, 10:29 PM

About 2K on the Mobil1 10W-30 full synth.

**Treibenschnell** · 10-30-2005, 07:01 PM

Okay... small update:

So far - new plugs, wires, 02 sensor, used working cat, a can of Seafoam, a tankful of Chevron Premium, a bottle of Guaranteed to Pass...

I'll try again later this week after I burn through this tank.

**Treibenschnell** · 11-03-2005, 05:36 PM

Make that 4 times that I've failed the test... oh so close... and it even gave me a retest.

**Titus** · 11-03-2005, 05:47 PM

Originally Posted by Treibenschnell

Make that 4 times that I've failed the test... oh so close... and it even gave me a retest.

Yikes... where do you go from here? In California, it wasn't uncommon for people to get a PO Box in a county that doesn't sniff annually. Probably not very legal, but doesn't seem much different than Bush listing TX as his primary residence rather than DC to save on his taxes.

**altiain** · 11-03-2005, 07:49 PM

Have you tried taping a $20 bill to the tailpipe and seeing if that helps you pass? Wink wink, nudge nudge, know what I mean?

**Majik** · 11-03-2005, 07:51 PM

How about a stock cat instead of a high flow?

**POS Racing** · 11-03-2005, 07:59 PM

Originally Posted by Majik

How about a stock cat instead of a high flow?

Yea that's what I was thinking my old POSII still had the original cat and 162K on the clock and it passed with flying colors....

What were todays test results???

Sombody around here with a 1.6 that has recently passed inspection havve a

they would be willing to loan Bean??

**POS Racing** · 11-04-2005, 10:21 AM

Well post up the test results Sparky!

**Titus** · 11-04-2005, 10:30 AM

Originally Posted by POS Racing

Sombody around here with a 1.6 that has recently passed inspection havve a

they would be willing to loan Bean??

I do, but he opted for the High flow cat I had sitting in a box rather than waiting for us to find time to swap out for the one on my car. Perhaps we can do a swap this weekend?

**MadMerv** · 11-04-2005, 10:41 AM

I've got a high flow on Sunny and no problems. I do, however, have a cat off of Speedie Jr that you could try. I really think you should consider getting the exhaust leak fixed, or replacing the header. I could probably come up with one of those, too! Too bad you're such a TCB.......

**Treibenschnell** · 11-04-2005, 10:54 AM

Originally Posted by Titus

I do, but he opted for the High flow cat I had sitting in a box rather than waiting for us to find time to swap out for the one on my car. Perhaps we can do a swap this weekend?

Perhaps I can talk you into coming by tonight... I can have them switched out in a flash.

Besides, this way I can put some hot time on the way to and from Mineral Wells this weekend.

**Titus** · 11-04-2005, 11:08 AM

Originally Posted by Treibenschnell

Perhaps I can talk you into coming by tonight... I can have them switched out in a flash.

Besides, this way I can put some hot time on the way to and from Mineral Wells this weekend.

Well you know me... got to clear it with the

first.

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