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GS Hog
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7,026 Posts
Discussion Starter · #1 · (Edited)
Up from the dead. Scroll down for latest. ;)

What kind of emissions readings do you guys get post-mods?

I just went to get my car smog checked, and although I passed, I'm kinda wondering about the results.

Two years ago, at its last check and pre-mod, the readings were as follows:

15 MPH

RPM: 1402
%CO2: 15.2
%O2: 0.0

HC (PPM)
MAX: 116
Ave: 12
Meas: 32

CO%
MAX: 0.47
Ave: 0.05
Meas: 0.01

NO (PPM)
MAX: 1398
Ave: 74
Meas: 29

25 MPH

RPM: 1293
%CO2: 15.1
%O2: 0.0

HC (PPM)
MAX: 66
Ave: 5
Meas: 16

CO%
MAX: 0.44
Ave: 0.02
Meas: 0.01

NO (PPM)
MAX: 1198
Ave: 78
Meas: 4

Now, post-mod (Chip, and exhaust - Intake was removed and replaced with stock box for test)

15 MPH

RPM: 1477
%CO2: 15.2
%O2: 0.2

HC (PPM)
MAX: 81
Ave: 12
Meas: 72

CO%
MAX: 0.47
Ave: 0.05
Meas: 0.25

NO (PPM)
MAX: 978
Ave: 74
Meas: 964

25 MPH

RPM: 1385
%CO2: 15.4
%O2: 0.0

HC (PPM)
MAX: 47
Ave: 5
Meas: 35

CO%
MAX: 0.44
Ave: 0.02
Meas: 0.04

NO (PPM)
MAX: 838
Ave: 78
Meas: 271

Now, are those results due to the fact that I smogged it with the chip in (with the stock intake), or is there something else that's causing these higher readings?

Just curious, but if it's a problem other than the chip, I'd like to rectify it. Thanks!

Sorry for the long post. :p
 

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Junior Mint
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629 Posts
My car was smogged about 1 year ago. At the time I had short ram intake, exhaust.

C02 and NO were almost undetectable. HC was about average reading.

I did the carbon cleaning of the throttle body and intake , etc. the day before going in. I would strongly recommend this. The results were much lower than any pre-mod readings.


I have not smogged with the chip in yet. I will prob put my stock one back in, since the modded chip is not a CA chip.

where did you go for the test? I went to this place on Duarte and Santa Anita in Arcadia. The guy saw the intake, but just checked to see if all the hoses were connected. He also checked for the cat.
 

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GS Hog
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7,026 Posts
Discussion Starter · #3 ·
I brought it to this place right around the corner from my house. First thing they did was pop to hood to look at the intake. :p I need to find a place that will do it with the intake on. Well, something to worry about in two years time. :)

Oddly, I put the stock intake back in for the test, and when driving it, I could feel a big difference from my CAI. My car felt "heavy".

I was going to put the stock chip back in, but I was in a bit of a rush. I'm really curious to find out if my chip coupled with the bad intake caused the high readings.
 

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502MotorSports.com
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9,296 Posts
LegendGS said:


Oddly, I put the stock intake back in for the test, and when driving it, I could feel a big difference from my CAI. My car felt "heavy".

I was going to put the stock chip back in, but I was in a bit of a rush. I'm really curious to find out if my chip coupled with the bad intake caused the high readings.
hmmm, did you reset the ECU when you swapped it out? (intake)
 

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E K said:
where did you go for the test? I went to this place on Duarte and Santa Anita in Arcadia. The guy saw the intake, but just checked to see if all the hoses were connected. He also checked for the cat.
:eek: Do you know the name and the address of this place?? I need to get mine smogged at Sep. and I really don't feel like putting the stock intake back in since it has a very tiny hole on it anyways.
 

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Junior Mint
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629 Posts
I think it's a shell station. Don't know the address. It's right on the NE corner.
 

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:( then I guess most likely they won't let me when I need to get the smog done.........
 

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GS Hog
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7,026 Posts
Discussion Starter · #9 ·
It's 2 years later and....

I failed!!!

Just got my car out of the body shop, and went straight to the smog station to get it tested as my tags expired while the car was in the shop.

I had it inspected with my CAI, Bayou chip, and exhaust still on the car. No other mods were done.

Here are my readings:

15 MPH
RPM 1422
CO2 14.64
O2 0.09

HC (PPM)
MAX 81
Ave 21
Meas 57

CO (%)
MAX 0.47
Ave 0.06
Meas 0.14

NO (PPM)
MAX 685
Ave 150
Meas 461

25 MPH
RPM 1310
CO2 14.60
O2 0.00

HC (PPM)
MAX 47
Ave 13
Meas 13

CO (%)
MAX 0.44
Ave 0.05
Meas 0.01

NO (PPM)
MAX 696
Ave 136
Meas 848 FAIL

I understand that the possible problems related to high NO are the EGR and Cat. The guy also suggested O2 sensors (although I don't have any errors at this time).

By looking at these readings, would someone be able to deduce further to determine by a narrower margin the culprit?

Thanks!

PS. One problem I'm having is that as mentioned, my tags have expired and can therefore not drive the car very much.
 

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hmm.....Why don't you try to put back the stock ECU, stock intake and stock exhaust (if possible) and go back for smog test?

if you pass, then indeed these mods are causing the failure. :confused:

Also, there's a smog station at the corner of Orangethorpe and Valley View St who's pretty easy going. The owner (a middle eastern guy) owns a green color Legend (last may when I got my GS smogged there) and loves to talk about Legends.
 

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GS Hog
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7,026 Posts
Discussion Starter · #12 ·
Yeah, I do plan to slap everything ('cept the muffler) back on just to be sure, but if all is healthy, I believe that it should pass even with the mods.

One thing I was wondering about was how long the cat needs to fully warm to optimum temperature.

I basically drove straight home from the body shop (maybe 1 mile), stopped to pick something up, and drove to the SMOG station (maybe another mile or so). The car had idled for a while at the body shop and the temp guage had shown that it was a operating temp. Also, the car has been sitting at the shop for a month before I picked it up. Could this have also affected my readings?
 

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LegendGS said:
Yeah, I do plan to slap everything ('cept the muffler) back on just to be sure, but if all is healthy, I believe that it should pass even with the mods.

One thing I was wondering about was how long the cat needs to fully warm to optimum temperature.

I basically drove straight home from the body shop (maybe 1 mile), stopped to pick something up, and drove to the SMOG station (maybe another mile or so). The car had idled for a while at the body shop and the temp guage had shown that it was a operating temp. Also, the car has been sitting at the shop for a month before I picked it up. Could this have also affected my readings?
The fact that your car was sitting for a long time may or may not have anything to do with bad readings. You never know.

Just to be safe, this time go with stock ECU and intake and make sure it's driven before you go in. (watch for cops, if you are driving with expired tags)

Check these posts:

http://www.legend-forum.com/vbulletin/search.php?searchid=11149
 

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Member
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LegendGS said:
Yeah, I do plan to slap everything ('cept the muffler) back on just to be sure, but if all is healthy, I believe that it should pass even with the mods.

One thing I was wondering about was how long the cat needs to fully warm to optimum temperature.

I basically drove straight home from the body shop (maybe 1 mile), stopped to pick something up, and drove to the SMOG station (maybe another mile or so). The car had idled for a while at the body shop and the temp guage had shown that it was a operating temp. Also, the car has been sitting at the shop for a month before I picked it up. Could this have also affected my readings?
My car had just smogged yesterday and I pass. If I we're you, get an extension at DMV and try to drive your car like 50 miles or so(just me) 'cause I heard that when you have your car smogged it's better to drive it harder or longer so that it may help to take out some carbon buildups(That's what I did)plus I live here in Newark, Ca. and I drive from Newark to Oakland to have my car smogged 'cause in Oakland they have this "No Pass, No pay" thing on smog checks :D. and it's more cheaper there like $20-$25 difference.
 

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GS Hog
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Discussion Starter · #18 ·
Yeah, I think I'll dump a can of BG44k in the tank, switch back to the stock chip, and run it.

How do I go about getting an extension from DMV?

Also, I've been trying to narrow the possibilities.

After doing some reading on the web, here's what I gather:

High NOx can be caused by a failing EGR, failing Cat, lean fuel mixture, higher than normal compression (caused by carbon buildup), and advanced timing.

However, a failing Cat also causes a high HC reading. My 15 MPH HC reading was 57 with an average of 21 and a maximum allowance of 81. My 25 MPH HC reading was 13 with an average of 13 and a maximum allowance of 47. Would this rule out the Cat?

As to the advanced timing, any bad conditions may have been further worsened by the Bayou chip. Hopefully, replacing the stock chip will bring the NOx down because of the reversion of the timing setting.

Not sure about the lean mixture.

I'll run BG44k through and test the EGR. Hopefully things work out fine after that. :p

Oh! Oil change too since it's due anyway. ;)
 

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8,236 Posts
ima get smogged in oct. and have a home depot Cai, will i pass? cuz my Legend will pass very easily stock as always, but im kinda worried about this one cuz i have a Cai and since it is ghetto looking, it will not pass the visual. Im also going to go to oakland for the test. first time on the dyno thingy. Anyone have a suggestion for whcih shop to go to?
 

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GS Hog
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7,026 Posts
Discussion Starter · #20 ·
I built my own CAI too and it passed the visual. Apparently, they primarily check to see that all hoses are hooked up as they should be (mine are).

I guess it depends on how picky the tech is.
 
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