LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Information on MAC headers 96-97

Old Jan 28, 2003 | 02:37 PM
  #16  
Chris 96 WS6's Avatar
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The answer to the question is not universal. If you live in California or another state with a strict emissions test regimine (that includes a visual component check), you are not going to be able to get away with swapping over to the 94-95 style setup.

However, here you can get away with it, and I would suspect in Little Rock AR you could as well.

Nationwide testing??? Where'd you get that. You will only ever see testing in "non attainment" areas, which is EPA codeword for areas who's air quality does not meet miminum federal standards. This is usually only bigger cities. So anybody in a small city or rural area is pretty safe. Its still technically against the law to disable emissions equipment regarless of whether you have testing or not, but the issue is if you are actually going to be caught and penalized. In areas w/o testing, there is no mechanism to catch you or monitor car owner behavior, so its just not an issue.

And it is true Florida did away with all testing. They decided the return on investment in terms of air quality improvements was getting smaller and smaller since new cars are cleaner and cleaner, so they scrapped the whole program statewide and are putting the money toward other environmental issues. I'm not entirely sure how they managed to ditch their program, since usually federal 80% share funding of interstate construction is at stake if your air quality doesn't measure up. My guess is that FL cities are close enough they figured they'd meet the air quality requirements w/o the testing and therefore not jeapardize billions in highway money.

I read so much mis-information on emissions testing. The bottom line is it varies from state to state and locale to locale, so find our what YOUR local test is like and how stringent it is and that will determine the course of action with your car.

They just started OBD2 testing here. Any car from 96+ now is plugged into a computer. They run a check for codes as well as a "hardware verification test" which is the PCM looking for stuff like rear 02 sensors, EGR solenoid, and AIR pump. If you have a code or if the PCM comes up saying any of the above are missing, you fail. Good news is no tailpipe test, bad news is its harder to get away with removing stuff. Luckily O2 simms still fool the PCM so that's not a problem. And you can leave the EGR solenoid installed while removing the EGR valve itself and turning it off in the PCM. AIR pump is a problem but there are actually 5 of these tests and you only have to pass any 3 of them.

Wisconsin and Georgia and a few other states are starting this kind of test too. And when I say states I mean where ever there is testing in that state, not that they are implementing statewide testing.

I need to do some research and write a good article on emissions stuff...
Old Jan 28, 2003 | 02:51 PM
  #17  
2L8 U LUZ's Avatar
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From: Bay Area, Ca
Nice Smog report

Hey nice smog report! So 93-95 Mac headers will bolt right up? I heard alot of people saying they wont fit? True or not? Ill probably just go with that setup and save me about 200dollars!
Old Jan 28, 2003 | 03:03 PM
  #18  
Chris 96 WS6's Avatar
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94-95 will fit, you'll need headers and Y-pipe, but 94-95 style headers almost always come with a Y-pipe so there is no problem. The only snag is that the 96-97 intermediate pipe is shorter, so you either have to have an "S" pipe fabbed to reach from the back of the single cat to the front of the catback, buy a 94-95 style catback, or find somebody who sells an S pipe. I used to hear that Thunder Racing had a pre-bent S pipe just for this conversion.
Old Jan 28, 2003 | 03:59 PM
  #19  
Red 97T/A A4's Avatar
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From: Bluff City, Tn
Thumbs up

Originally posted by Chris 96 WS6
And you can leave the EGR solenoid installed while removing the EGR valve itself and turning it off in the PCM. AIR pump is a problem but there are actually 5 of these tests and you only have to pass any 3 of them.
Thanks for the info Chris. We have no testing here...yet. I've been worried we would since I've had an EGR code that won't go away since the FLPs went in.
Old Jan 28, 2003 | 04:39 PM
  #20  
Chris 96 WS6's Avatar
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You probably have code P0400, low EGR flow. Its unavoidable since the headers flow so well there is no backpressure to force exhaust gasses into the EGR valve. Engine vacuum apparently isn't enough to do it alone. Using LT1 edit you can simply turn off the EGR function (actually you set the enable RPM really high so it will never activate) and leave the solenoid, etc.
Old Jan 28, 2003 | 05:47 PM
  #21  
drop top steve's Avatar
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Originally posted by Chris 96 WS6

I read so much mis-information on emissions testing. The bottom line is it varies from state to state and locale to locale, so find our what YOUR local test is like and how stringent it is and that will determine the course of action with your car.
The EPA has established federal guide lines, to take effect in 2006, for all obdi and obdii cars to pass minimum requirments.
Some people are seeing this new obdii testing now, I have it here in my city, but fifty miles done the road, different county, no testing. The new guide lines requires all cars be tested, non compliant states may lose federal money.
I would think any state facing the loss of federal funds well implement testing.
Chris, I well try to find some more info on this and forward it to you.
Old Jan 28, 2003 | 05:53 PM
  #22  
darkoverlift's Avatar
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Do the federal funds pay for the testing? See they have to see how much wil lthey lose and what it will cost.. Cost Benefit Ratio...
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