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Smog fail. need to run leaner

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Old 09-13-2010, 02:11 PM
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Default Smog fail. need to run leaner

My 02 z06 barely failed the smog test. Seems im running a bit rich. what the best way to lean out using hp tuners?
Old 09-13-2010, 02:55 PM
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Originally Posted by qs_zo6
My 02 z06 barely failed the smog test. Seems im running a bit rich. what the best way to lean out using hp tuners?
How bout posting the test results, and the mods done to your car. Tune file would help too.
Old 09-13-2010, 05:45 PM
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Originally Posted by edcmat-l1
How bout posting the test results, and the mods done to your car. Tune file would help too.
lg longtubes w/cats
haltech trap w/license plate cut out
borla stinger exhaust

tune and smog attached. thanks
Attached Thumbnails Smog fail. need to run leaner-smog.jpg  
Attached Files
File Type: hpt
02-Z06-MOD-TUNE-8-31-2010.hpt (456.8 KB, 70 views)

Last edited by qs_zo6; 09-13-2010 at 06:01 PM.
Old 09-13-2010, 09:14 PM
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how old are your front o2's?
Old 09-13-2010, 09:22 PM
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IMO 0.3 CO2 isn't really excessively rich. My guess would be your cat's aren't very efficient. How long was the car off before they put it on the rollers?
Old 09-13-2010, 10:13 PM
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It's his HC count
Old 09-13-2010, 10:17 PM
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Originally Posted by SoCal01z28
IMO 0.3 CO2 isn't really excessively rich. My guess would be your cat's aren't very efficient. How long was the car off before they put it on the rollers?
i drove for an hour to get the cats hot and put it straight on the rollers.

frost is correct my HC is high. what can i do to bring it down?
Old 09-14-2010, 06:10 AM
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Originally Posted by Frost
how old are your front o2's?
How old are they?
Old 09-14-2010, 12:52 PM
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Originally Posted by Frost
It's his HC count
I understand that, but he said he's rich. CO% is a direct indicator of a/f mixture.....
Old 09-14-2010, 01:03 PM
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Originally Posted by MUSTANGBRKR02
How old are they?
they or the factory o2s 37000 miles
Old 09-14-2010, 01:29 PM
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Are there any quick tweaks to bring down the HC for the few minutes of the smog? Not hurting the engine of course then i can go back to my original tune.
Old 09-14-2010, 03:59 PM
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Originally Posted by qs_zo6
they or the factory o2s 37000 miles
...but they are 9 years old...
Old 09-14-2010, 04:16 PM
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Default hmmm

I really hope they dont get emissions in oklahoma or were all screwed out here lol . you can use hp tuners to lean out your car but you need to make sure everything else is in order .. are your headers leaking ? o2s fluctuating or are they lazy? lots of things can cause a rich condition

Last edited by whtrashferrari; 09-14-2010 at 04:23 PM.
Old 09-15-2010, 01:56 PM
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anyone have suggestions on tweaks i can do or do i need to buy new 02s and pray it passes?
Old 09-15-2010, 02:27 PM
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i think you need a new set of cats. Get a new, high quality set and you should be ok. The o2's are probably fine since you aren't throwing any codes.

I went thru the same **** with ca smog... put the factory manifolds and cats back on and I passed.
Old 09-15-2010, 02:33 PM
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If you have your own software, run a data log of it idling. In the data log, include fuel trims, both short and long term, and both upstream and downstream O2s. I would almost guarantee it's a catalyst efficiency issue. Both your Hcs and CO2 are borderline. If it is a catalyst efficiency problem, not much you can do with high flow cats. Shoot me a PM for more details.

Looking back at your mods, I believe the LG longtubes put the cats way in the back, as opposed to right behind the headers. They never get hot enough (the cats) to kick on.
Old 09-15-2010, 03:04 PM
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I think you want brand new O2 sensors and you want them
as hot as possible. The headers hurt that, making the sensors
switch more slowly and when they do your mixture (while on
average, perhaps right) spends a lot more time off in the
weeds, lean, rich, lean rather than tight, tight, tight. Out in
the weeds is where you make HC. If you want to look into
this, turn off the filtering on your wideband and log real time
idle AFR. If it's bouncing crazy, there's your HC.

I'd consider wrapping the collector for maybe 6" before and
after the sensor with a heat barrier. At least until you get
your sticker.
Old 09-15-2010, 07:39 PM
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+1 on taking logs to see how O2's are switching... you probably do need new 02 sensors.

Are coldair/headers/exhaust the only mods you have...? Your emissions should be well below the average. I can't read the .hpt file, so summarize for us what has been edited in the tune.

How did you get past visual...?




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