Need smog analysis - Failed smog 4 times.

lazyboyz69 · 8 August 2013

I was in the process of selling my car, but the buyer backed out due to car failing smog four times. So I need some help on doing some analysis on why my car is failing smog. I would like the nsx run as most efficiently as possible. The car has fresh oil, new oil filter, cleaned air filter, cleaned out the throttle body. Spark plugs are fairly new, I got some used coil packs. Here are the results

		%CO	&O2	HC (PPM)	CO(%)	NO(%)
Test	RPM	MEAS	MEAS	MAX	AVE	MEAS	MAX	AVE	MEAS	MAX	AVE	MEAS
15 mph	1593	13.9	0.5	86	23	224	0.5	0.08	0.61	697	194	667
25mph	1714	14.6	0	51	14	52	0.48	0.06	0.04	724	166	211

		%CO	&O2	HC (PPM)	CO(%)	NO(%)
Test	RPM	MEAS	MEAS	MAX	AVE	MEAS	MAX	AVE	MEAS	MAX	AVE	MEAS
15 mph	1553	14.4	0.1	86	23	97	0.5	0.08	0.15	697	194	322
25mph	2497	14.4	0	51	14	89	0.48	0.06	0.28	724	166	95

		%CO	&O2	HC (PPM)	CO(%)	NO(%)
Test	RPM	MEAS	MEAS	MAX	AVE	MEAS	MAX	AVE	MEAS	MAX	AVE	MEAS
15 mph	1563	14	0.3	86	23	165	0.5	0.08	0.41	697	194	719
25mph	2529	14.3	0	51	14	117	0.48	0.06	0.38	724	166	128

		%CO	&O2	HC (PPM)	CO(%)	NO(%)
Test	RPM	MEAS	MEAS	MAX	AVE	MEAS	MAX	AVE	MEAS	MAX	AVE	MEAS
15 mph	1565	14.4	0.3	86	23	130	0.5	0.08	0.39	697	194	596
25mph	2521	14.6	0	51	14	96	0.48	0.06	0.4	724	166	288

1st run- I changed out the front 02 sensor- I thought I would pass smog.
2nd run - I changed out the rear 02 sensor - I thought I would pass smog.
3rd run - Cleaned outtthe IAT sensor - since the second reading was much lower i thought forsure i would pass.
4th run - desperate attempt I tried "Guarantee to Pass" at Auto Zone - Didn't pass.

I changed out the o2 sensor with NTK that I got from Amazon. My car is 1993 and only mods I have is DC headers, Flowmaster Exhaust and Uni Filter. I also have 160k miles.

My thought are I have a leaky fuel injector, would that cause my HC to be high or do I have a bad cat? Or my spark plugs are bad - I've been putting Chevron fuel injector cleaner and sea-foam in my car would that have messed up the spark plugs?

Another thought, When i reset my ecu via "clock fuse" I start the car starts up fine, but when I press a little gas, the idle jumps up and down, up and down until i drive like 100 miles or so. And it only does it when i'm at idle.

Your thoughts please. Thanks in advance!

snipesusaf · 9 August 2013

This is eerily similar to my situation... I cleaned me IAT, changed 02’s, used the “guaranteedto pass” at Auto Zone. I have DC headers, comptech exhaust and I also failed 4times too. I’m still trying to figure it out. hmm I’m thinking bad CATS, I also heard the DCheaders are hard to pass with. When youfigure it out let me know, since were are in the same boat. GL <o

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lazyboyz69 said:
I was in the process of selling my car, but the buyer backed out due to car failing smog four times. So I need some help on doing some analysis on why my car is failing smog. I would like the nsx run as most efficiently as possible. The car has fresh oil, new oil filter, cleaned air filter, cleaned out the throttle body. Spark plugs are fairly new, I got some used coil packs. Here are the results

%CO
&O2
HC (PPM)
CO(%)
NO(%)

Test
RPM
MEAS
MEAS
MAX
AVE
MEAS
MAX
AVE
MEAS
MAX
AVE
MEAS

15 mph
1593
13.9
0.5
86
23
224
0.5
0.08
0.61
697
194
667

25mph
1714
14.6
51
14
52
0.48
0.06
0.04
724
166
211

%CO
&O2
HC (PPM)
CO(%)
NO(%)

Test
RPM
MEAS
MEAS
MAX
AVE
MEAS
MAX
AVE
MEAS
MAX
AVE
MEAS

15 mph
1553
14.4
0.1
86
23
97
0.5
0.08
0.15
697
194
322

25mph
2497
14.4
51
14
89
0.48
0.06
0.28
724
166
95

%CO
&O2
HC (PPM)
CO(%)
NO(%)

Test
RPM
MEAS
MEAS
MAX
AVE
MEAS
MAX
AVE
MEAS
MAX
AVE
MEAS

15 mph
1563
14
0.3
86
23
165
0.5
0.08
0.41
697
194
719

25mph
2529
14.3
51
14
117
0.48
0.06
0.38
724
166
128

%CO
&O2
HC (PPM)
CO(%)
NO(%)

Test
RPM
MEAS
MEAS
MAX
AVE
MEAS
MAX
AVE
MEAS
MAX
AVE
MEAS

15 mph
1565
14.4
0.3
86
23
130
0.5
0.08
0.39
697
194
596

25mph
2521
14.6
51
14
96
0.48
0.06
0.4
724
166
288

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</tbody>

1st run- I changed out the front 02 sensor- I thought I would pass smog.
2nd run - I changed out the rear 02 sensor - I thought I would pass smog.
3rd run - Cleaned outtthe IAT sensor - since the second reading was much lower i thought forsure i would pass.
4th run - desperate attempt I tried "Guarantee to Pass" at Auto Zone - Didn't pass.

I changed out the o2 sensor with NTK that I got from Amazon. My car is 1993 and only mods I have is DC headers, Flowmaster Exhaust and Uni Filter. I also have 160k miles.

My thought are I have a leaky fuel injector, would that cause my HC to be high or do I have a bad cat? Or my spark plugs are bad - I've been putting Chevron fuel injector cleaner and sea-foam in my car would that have messed up the spark plugs?

Another thought, When i reset my ecu via "clock fuse" I start the car starts up fine, but when I press a little gas, the idle jumps up and down, up and down until i drive like 100 miles or so. And it only does it when i'm at idle.

Your thoughts please. Thanks in advance!

dablackgoku1234 · 9 August 2013

160k miles on OEM cats? When is the last time you changed the spark plugs? Did you run the car nice and hot before you went in for the test? When is the last time you saw 8000rpm?

Also, when you say "putting seafoam" in the car, did you do the 3 part method or just in the gas tank?

lazyboyz69 · 9 August 2013

Yeah 160k on OEM Cats, last time I changed spark plugs was 20k miles ago. I did run the car nice and hot before the test (maybe it was luke warm) 2nd run forsure hot, I left the car running while I was waiting as well, I didn't wait that long. I was gunning it pretty hard when I put the "Guarantee to Pass" in the car, but I do baby the car. Should I do hit VTEC couple of more times? The idle jumping up and down went away. I didn't pull the "clock fuse" after cleaning the IAT sensor. I just recently did that.

I did put seafoam in the car, half in the gas tank, the other half in the crank.

I'm going to have my injectors cleaned at RC Engineering and I'm going to test the coil packs this weekend.

dablackgoku1234 · 9 August 2013

One thing for sure is that your OEM cats are probably nearing the end of their lives. Spark plugs should be good if they were replaces 20k miles ago. Hitting VTEC a few more times *should* clear out some carbon buildup, as well, getting your injectors cleaned should result in a better burn. All of this should help reduce your HC reading.

The last thing you can do, but I'm not sure if there are any effects of it on emissions, is putting seafoam thru your intake vacuum hose so it goes directly into the engine.

solidol · 10 August 2013

Where are you located? Given all you did I would hook up with local member and swap cats for test run.

lazyboyz69 · 14 August 2013

On my front bank DC Headers, the O2 sensor is pointing to the firewall/Gas Tank. The O2 sensor bung hole is pretty much at the top/middle of the header. Is this correct? Does it need to be placed near the bottom or the near the collector portion? Would that make the car run rich?

snipesusaf · 5 December 2013

Finally past... Bought cats from a scrap yard. Problem solved.

BATMANs · 5 December 2013

http://www.nsxprime.com/forum/showt...verter/page2?p=1453047&viewfull=1#post1453047

Magnaflow is suppose to have OBD-II California legal cats for the new NSXs, but you will need to input your year to get an exact match. I don't think it's an angled cat like the ones below, but a universal cat that they tested and determined that will meet CA smog requirements.

These 2 Magnaflow cat options are Pre-OBD-II and should work for the 94 and older NSX:

IN/OUT PART#
2" 91074
2.25" 91075
2.50" 91076

EPA-FEDERAL ENGINE LIMIT: 256 CID/4.2L
TEST WEIGHT: 4500 lbs.

IN/OUT PART#
2" 91084
2.25" 91085
2.50" 91086

EPA-FEDERAL ENGINE LIMIT: 256 CID/4.2L
TEST WEIGHT: 4500 lbs.

Ebay sells these cats for around $75.

lazyboyz69 · 26 August 2014

	%CO	&O2	HC (PPM)	CO(%)	NO(%)
RPM	MEAS	MEAS	MAX	AVE	MEAS	MAX	AVE	MEAS	MAX	AVE	MEAS
1527	14.5	0.2	86	23	85	0.5	0.08	0.05	697	194	542	Pass
2448	14.4	0	51	14	92	0.48	0.06	0.27	724	166	505	Fail

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</tbody>

Here are my most recent results. I've changed the oil, cleaned out the air filter, cleaned out the AIT sensor, placed new cats. I still need help.

I just cleaned out EGR valve, New Spark plugs, I was using double platinum spark plugs instead of laser platinum plug. Think this would make me pass?

nsx20014me · 28 August 2014

Did you get your injectors cleaned?

lazyboyz69 · 28 August 2014

never got the injectors cleaned.

lithiumus · 15 September 2014

You say you cleaned the AIT sensor but have you considered changing it out? While my problem was slightly different than yours as I was failing idle rather than failing higher RPM, cleaning the AIT did not help and I had to replace it to pass.

Need smog analysis - Failed smog 4 times.

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