Long tube header dilemma
04-05-2012, 02:41 PM
#1
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Long tube header dilemma So I recently bought a 94 lt1 trans am already fitted with pace setter "race" long tubes without emissions hookups and a cat-less Y-pipe... Unfortunately I live in a county where the sniffer emissions test is required. So after some cutting, welding, and fancy custom fab I have a functional egr system and cats. Now in my attempt at the emissions place I was sent home with a failure notice for "high hydrocarbons" which I understand is unburned fuel passing through the exhaust.. Am I going to have to figure out a way to attach my air injection system to these pain in the rear headers? In my understanding the air injection's soul purpouse is to burn raw fuel in the exhaust, correct?
I'd rather not cut and weld anymore on the headers if possible so any alternatives would be apreciated
I'd rather not cut and weld anymore on the headers if possible so any alternatives would be apreciated
04-05-2012, 04:55 PM
#3
Maybe to late now but I would have just got a set of stock manifolds and y with cat('S) and passed then swapped back to LT's or just sold the LT's and gone with emissions legal shorties. This is always a problem to get the cats hot enough to burn everything off. How close are they to the collector? and what size are they?
04-05-2012, 07:57 PM
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Yeah, if I had everything I needed to throw the stock exhaust back together I probably would, but I'm kind of stuck in the situation I'm in. Now as far as the cats go, I'm running three inch diameter in/out mounted about two inches off of the collector on the right bank and about 8 inches back on the left bank.. My numbers weren't terribly far off on my test results. Could this be as simple as running it hard down the freeway for a few miles and getting everything warmed up? I had the temp at about 210 when I had it tested but I'm sure I could get the cats hotter
04-06-2012, 06:50 AM
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I think you guys would be proud of my fancy egr feed tube though. Welded a plumbing fitting into the collector and another on the plate mounted to the back of the intake and ran a natural gas feed line for a dryer "corrugated steel" between them
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04-16-2012, 12:29 PM
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Well i made another attempt at the emissions test, made sure I had the cats were nice and toasty this time. My numbers were better though i still Failed again for hydrocarbons.
This time the manager there used her little handheld fuel vapor reader and told me I have a leaky seal on the filler neck of my gas tank causing vapor to be sucked into the sniffer hose.. According to her this is a common trans am and firebird problem, anyone ever heard of it? Could this really be my problem?
This time the manager there used her little handheld fuel vapor reader and told me I have a leaky seal on the filler neck of my gas tank causing vapor to be sucked into the sniffer hose.. According to her this is a common trans am and firebird problem, anyone ever heard of it? Could this really be my problem?
04-16-2012, 12:47 PM
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What are your numbers when failing? I'm in portage so we're not to far from each other. I failed with my car a few weeks ago as well. Everything passed but Hydrocarbons. Passing is .80 and I had a 1.25. The lady that worked at the clean air check ran the sniffer on my camaro and it set off the sniffer at my gas tank as well. I don't think your filler neck is messed up because I thought mine was leaking but I did research and its looking like there is something wrong with the EVAP system not venting properly. I ordered a new charcoal canister and EVAP purge solenoid for my car, I plan to install it this weekend. When you open your gas cap does your tank hiss out a bunch of air?
04-16-2012, 04:34 PM
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My numbers are actually the same, and I don't usually get pressure in the tank unless the car is running, and in that case I get a small hiss, but it's hard to say whether it's outward pressure or inward vacuum.
04-16-2012, 05:18 PM
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We shouldn't be hearing a hiss at all. The tank is vented so there won't be any pressure in the tank or anything suction going in. At least not supposed to. Mine hiss's bad especially when its around 1/8th of a tank.
04-17-2012, 01:25 PM
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Well I may have fixed my problem, put her up on the lift yesterday to check out the evap can and everything associated, found the hose running from the charcoal can to the fuel tank had been cut. A few minutes spent contortioning my arms up there with a screw driver and a hose clamp and I may have fixed the source of my leaking fuel vapors
04-17-2012, 01:50 PM
#20
You need to find out if factory tune program has been modified, that may be why you are failing emissions, especially since this car what outfitted with no egr and long tube headers.. just my thoughts.. my 95 z28 is programmed for performance tune, but when time for tailpipe test, i reprogram to different tune for emissions testing