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Discussion Starter · #1 ·
Took my 91 in for its emissions test last Friday and wasn't sure it would pass it. It didn't....:mad:
Did just fine on the high speed test but failed the idle test. HC was 325ppm. max was 140. Since I have long tube headers, high flow cats and a dual 3" exhaust I suspected that there just wasn't enough flow at idle to keep the cats lit. Over the weekend I made a exhaust cap to seal off the right side of my exhaust and made a 1/2 cap to fit in the other side so that everything would flow out just one side. Stopped by the station last night on the way home and got it retested. Passed it no problem, idle HC was 115ppm so my assumption was correct. Now I'm good to go for another 2 years. Waited till the exhaust had cooled off then unbolted my caps and now will stash them for next time.
 

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Good point about the Cat temps, they have to be hot to work. My emmissions spiked when I went to headers, 3" single and a hi flow cat, I figured it was probably because there was just less mesh on the hi flow cat. it puts me right on the edge, and I will always fail at idle if I don't change the oil before a test. Although, I haven't been emmision tested since going to EBL Flash, good tuning will probably help in my case.
 

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If Indiana starts testing again one of these years I have about no idea what I'll do. Not a bit of emissions crap left on anything here. Literally cheaper and easier to get my dealers license again and run it part time than try and put all the garbage back on I believe.
 

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If Indiana starts testing again one of these years I have about no idea what I'll do. Not a bit of emissions crap left on anything here. Literally cheaper and easier to get my dealers license again and run it part time than try and put all the garbage back on I believe.
In Washington State we have tail pipe only. I bet I could run a big block and pass...
 

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Discussion Starter · #5 ·
Some states are a tailpipe test only so all you may need to do is toss on a set of cats and be done with it.

Here they check for air pump if factory equipped, look under the car for the presence of cats, check the fuel cap then run an idle test and a high rpm test (2200-2800).


Been told that some of the Impala's will actually pass smog tests without cats.
 

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Some states are a tailpipe test only so all you may need to do is toss on a set of cats and be done with it.

Here they check for air pump if factory equipped, look under the car for the presence of cats, check the fuel cap then run an idle test and a high rpm test (2200-2800).


Been told that some of the Impala's will actually pass smog tests without cats.
Did they check for the air pump? I asked an employee at an Albuquerque emissions booth a couple of months ago, and he said that they don't do that.
 

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Discussion Starter · #7 ·
Part of the inspection. I have the TSB and the sticker for my 95 that says that I don't have to have one cause they do ask why its not there.
 

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Took my 91 in for its emissions test last Friday and wasn't sure it would pass it. It didn't....:mad:
Did just fine on the high speed test but failed the idle test. HC was 325ppm. max was 140. Since I have long tube headers, high flow cats and a dual 3" exhaust I suspected that there just wasn't enough flow at idle to keep the cats lit. Over the weekend I made a exhaust cap to seal off the right side of my exhaust and made a 1/2 cap to fit in the other side so that everything would flow out just one side. Stopped by the station last night on the way home and got it retested. Passed it no problem, idle HC was 115ppm so my assumption was correct. Now I'm good to go for another 2 years. Waited till the exhaust had cooled off then unbolted my caps and now will stash them for next time.
Any pics, I think I might have to do this on my 92 TBI LO5, I think it might be because of the LT1 manifolds and catalytic converter setup I did I cant pass emissions.I will assume that the O2 sensor is opening prematurely because the cats are not hot enough and not enough back pressure.The wagon is running to rich and pushing black smoke on takeoff.The RMW is at the shop now.any help would be great.
stock setup whats on the wagon now
 

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Discussion Starter · #9 ·
Looks like stock manifolds, cats and pipes. No mufflers?
 

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Some states are a tailpipe test only so all you may need to do is toss on a set of cats and be done with it.

Here they check for air pump if factory equipped, look under the car for the presence of cats, check the fuel cap then run an idle test and a high rpm test (2200-2800).


Been told that some of the Impala's will actually pass smog tests without cats.
My car failed Utah tail pipe emissions without cats. My buddys 9c1 failed also
 
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