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Discussion Starter #1
I went to get smog checked last week and the car failed. I'm looking for some of the pros to give me a recommendation of what I should look for to get things right again.

Test Results:
@15 MPH - FAIL

  • CO2 %: 14.2
  • O2 %: 0.7
  • HC (PPM): 158 (max 66)
  • CO %: 0.35
  • NO (PPM): 561 (max 487)
@25 MPH - PASS

  • CO2 %: 14.8
  • O2 %: 0.1
  • HC (PPM): 42
  • CO %: 0.03
  • NO (PPM): 146
Other info:
I have an AEM Intake and TTE exchaust. I usually run with a Unichip, but had taken it out a few weeks prior. When I took out the unichip, my engine threw a cell for bad O2 sensor. I replaced both of the O2 sensors in the header at the same time and they both worked fine (checked with OBDII scanner that they return numbers and no CEL).

Any ideas why the HC and NO are out of whack?
 

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George is the Smog Guru.. But I can look at it through my Eyes..

Can you get the Fuel Trims at Idle?..

Post them..

Wondering about leaking Injector.. Also Compression Test to see the Health of the Engine..


What is the Mfg Date on the Door Sticker ( If it's the Same Engine ).. That'll tell me what Cams you have ..

Cap
 

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Discussion Starter #3
Can you get the Fuel Trims at Idle?..
Long Term Fuel Trim @ idle: -8
Short Term Fuel Trim @ idle: -3

Long Term Fuel Trim @ 2000rpm (about equivalent of 15MPH on the emissions test): 0
Short Term Fuel Trim @ 2000rpm (about equivalent of 15MPH on the emissions test): bounces between 3 & -5

Wondering about leaking Injector.. Also Compression Test to see the Health of the Engine..
Don't really have the equipment or skills to do this test myself.

What is the Mfg Date on the Door Sticker ( If it's the Same Engine )
Engine is stock mfd date: 05/00 (~75k miles)

That'll tell me what Cams you have
Stock cams.
 

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The fuel Trims should be in Bank 1 and Bank 2 I need the Different Banks long and Short of each bank.. ( Unless your 2ZZ )

The 02/00 Mfg date should indicate ( If my theory is Corect ), that you have the Cams that will Cause high Copmpession Numbers.. 'Bout 200's .. I Forget the Cut Off date ( I have it in my Notes ), but after about '02 the Cams were change, and the Compression Numbers will be in the 180's

It'd be great if you could do compression .. Not hard to do.. Like changing Pugs.. ( Sorta ).. Need a Screw in compression Tester.. $30..

The 'How To' Files have Blackcreeks write up in how to do it..

Cap
 

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Discussion Starter #5
The fuel Trims should be in Bank 1 and Bank 2 I need the Different Banks long and Short of each bank.
Cap
Bank 1:
Long Term Fuel Trim @ idle: -8
Short Term Fuel Trim @ idle: -3

Bank 2:
Long Term Fuel Trim @ idle: -8
Short Term Fuel Trim @ idle: bounces between 0 and -3
 

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That shoots my Theory of one of the Injectors being bad.. The Trims are really close, and if one injector was leaking or cloged, then the Two banks would be way different..

For ~80K mi the compression numbers should still be good.. But that would be the next route to check.. looking for leaking valves..

Do you have pre-cats?..

Was the Car HOT before the test?.. ( It should have been )

Cap
 

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Discussion Starter #7
Good questions. The precats are gutted. The car was hot on the way to the test but it sat idling for about 15 minutes before the actual test. The temp guage was still showing that the car was hot when it was pulled into the garage.

What concerns me is how much over the limits my car was. Not sure if heating it up more would bring me down within limits:
HC (PPM): 158 (max 66) <-- 3 times what it should be.
NO (PPM): 561 (max 487) <-- almost 20% higher than it should be.
 

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I'll link this to george, and see if he has any Ideas..

Cap
 

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How old is your main cat? My friend's results were similar @ 100k, so he swapped cats with someone with 30k. Passed with flying colors.
 

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How old is your main cat? My friend's results were similar @ 100k, so he swapped cats with someone with 30k. Passed with flying colors.
You're definitely on to something there Guy. To fail on both HC & NOx is indicative of an under efficient catalytic converter. The fact that you passed at higher RPM (higher rpm = higher velocity hotter exhaust gas = slightly more efficient cat) also points toward your catalytic converter. A newer cat would most probably pass.
 

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Discussion Starter #12
YTo fail on both HC & NOx is indicative of an under efficient catalytic converter. The fact that you passed at higher RPM (higher rpm = higher velocity hotter exhaust gas = slightly more efficient cat) also points toward your catalytic converter. A newer cat would most probably pass.
Hmm, I thought the HCs would depend on EGR, plugs, timing etc. It's odd that both HCs and NOx are high as they are almost opposite type problems.
 

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I think that all these people are crazy and that you just have a wearing out cat. Although the last time I tested it was a load and then idle test, no 15mph. I wonder if it is 2nd gear 15mph or first, that would make a difference.

Enable your PMs I have a few things you can try if you want.
 

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I think your cat just cooled down

if you notice its all around failure and you have almost 1% oxygen (o2), oxygen that is not being used by the cat to burn all other emissions and create more carbon dioxide (co2) [gas you dont fail for]. then at 25mph once HOT, oxygen got used up and co2 went up and all your other readouts dropped. You sure the car was warm? did it sit a long while before tested (off)? i think personally it just wasnt warm enough, or your cat might just be old and getting to slow to get where it needs to be.

I would, if it was my car i would sit in it couple minutes before you hand the keys over and just rev it 1500-2000rpm. Theres nothing that says you cant do that. even if they write you up and all just sit in it and rev till its your turn. if that doesnt work i say start looking at cats, because your fuel trims look decent enough.
 

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Damn, you ARE good George.

I passed with at gutted cat with a 150K motor. I drove the heck out of it before the smog and made sure the engine was running while waiting. I only waited a few minutes though.

Goodluck.
 

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Sooo..

Good Loaner Pre-Cats might help also??..

Cap
 

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I also think it was just not warmed up.
 

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Discussion Starter #18 (Edited)
So, I was taking your advice about warming up the car and going in for a retest. I'm out on the highway, riding it around 4000rpm and I get a CEL.

Codes: P0171 and P0174 (running too lean in bank 1 and 2)

Bank 1:
Long Term Fuel Trim @ idle: -6
Short Term Fuel Trim @ idle: -7

Bank 2:
Long Term Fuel Trim @ idle: -4
Short Term Fuel Trim @ idle: -9

Leads me to think it isn't the cat. I'm running the stock ECU and just filled up the gas today.

I guess the next steps are:

  • Clean the MAF and see if it fixes things
  • Start checking the vacuum lines
Any other suggestions?

UPDATE: Found a loose clamp between the AEM intake and the elbow that connects to the engine. Going to tighten it and hope that solves the problem.
 

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loaner pre cats would make it the easiet lol, but just give it a good warm up you should be fine,

after you get your code cleared and figured out
 

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did you let the stock ecu relearn after removing unichip it can take a few trips to accomplish this hence funny readings at least a couple days before the test it should pass fine with unichip installed mine does
 
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