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Discussion Starter · #1 ·
Too much hydrocarbon output at 2500rpm. I've got a godspeed uppipe and turboxs stealthback with cat. I was surprised when they told me it failed. I think I can pass on race fuel. What do you think?

-Jim
 

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Excessive HC is unburned fuel out the tailpipe.

Do you have any fuel mods? Was the car in closed loop with the cat fully warmed up?
 

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whoa jim that sucks!! i have the stock midpipe so that's 1 cat there and i hope i don't fail come that time in June. Was the car fully warmed up. Go beat the snot out of it then take if again. orrrrrrrrrrrrr just throw another cat on take it pass then boom mods again. or buy the guy a case of beer!!
 

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I've heard that 1 cat won't pass smog but 2 will. Not sure on why. But I recently had to replace the whole stock downpipe to pass smog. It was a pain but it passed with flying colors.

BTW: I had a Gruppe-s UP on there and swapped out my HKS DP for the stock.
 

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You removed the emission controls and it failed the emissions test? Go figure.
 

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its the TXS cat, it's basically useless for filtering.

what i don't understand is, if the TXS cat doesn't pass emissions, why the hell buy one?! :confused:

i'd up the boost a bit jim, watch the A/F, but lean it out, and you'll get rid of the unburnt fuel.

dR
 

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dark_rex said:
i'd up the boost a bit jim, watch the A/F, but lean it out, and you'll get rid of the unburnt fuel.

dR
I'd actually try to get the boost as low as possible to try to keep the car in closed loop. At stoichiometric mixtures, you are less likely to get unburned hydrocarbons in your exhaust.
 

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Discussion Starter · #13 ·
dark_rex said:
what i don't understand is, if the TXS cat doesn't pass emissions, why the hell buy one?! :confused:

i'd up the boost a bit jim, watch the A/F, but lean it out, and you'll get rid of the unburnt fuel.

dR
Exactly. What's the point of having a cat if your car won't pass emissions?

Boost isn't really a factor considering it was only at 2500rpm. VF30 isn't making any boost that low.

-Jim
 

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throw the stock dowpipe on and right before you go back to re-smog run your car on a freeway for about 10-15 minutes off and on boost so the cats are really hot. your car will pass with flying colors.
 

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Rich10 said:
I'd actually try to get the boost as low as possible to try to keep the car in closed loop. At stoichiometric mixtures, you are less likely to get unburned hydrocarbons in your exhaust.
:confused:

open/closed loop is based entirely on throttle position. whatever your boost is doesn't matter.

jim are you using a bleeder or ball and spring MBC? w/ a bleeder, you might be allowing the w/g to open up a hair, and lose some boost. just a thought.

any other ways to easily increase MAF? what's your intake setup. airbox hacks tend to make more MAF at lower RPMs. ...

otherwise, yeah, just make sure that car is god and hot. i'm figuring some spirited 3rd and 4th gear highway driving will do the trick.

dR
 

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I'd just put the stock turboback one everytime you get inspected. I wouldn't even risk it.

My $.02
 

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TypeC said:
I'd just put the stock turboback one everytime you get inspected. I wouldn't even risk it.

My $.02
too bad not all of us can turn a wrench. :( or have a lift. :( :(

that's why i unfortunately need to keep that last pesky cat. although i suppose i can pull some strings at the customer shops of my dad's stores. they've done it before.

dR
 
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