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Performance upgrades and better emissions, oxymoron?

Discussion in 'The Garage' started by chris672, May 26, 2002.

  1. chris672

    chris672 1/2 ton status

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    Location:
    LODI, CA
    I want to get some parts for the engine in my 89 Jimmy (350 TBI) but I live in CA and my truck barely passed smog the last time it was tested. Are there any parts that I could put on it and not make the emissions worse? I already have a K&N filter.
     
  2. lizard

    lizard 1/2 ton status

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    Location:
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    If it barely passed the test you should probably start with an engine tuneup, check the compression, etc. You can't make a worn out engine perform much better if it needs a rebuild. That said there are lots of emissions legal stuff - headers, cams, intakes just like pre emission days (remember?)

    If you dont mind spending 300-400 on tools you can reprogram your computer for better performance without touching the engine. If you do modify the engine you'll want to burn/buy a new chip anyway.

    http://www.mindspring.com/~amattei/akmelect.htm

    Before I found these sites you couldn't have given me a computer. Now I love EFI :-)
     
  3. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Location:
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    Tune up like was pointed out and a new O2 sensor. O2'sensors are supose to be replaced every 60K and if you don't know how long it's been then replace it. Most people fail emmisions tests on efi vehicle out of lack of knowledge of one simple thing. The truck is not up to operating temp. NEVER pull into a emmsions test till the vehicle has been run for at least 15 minutes preferably at hwy speed to get the cat good and hot and DO NOT SHUT THE ENGINE OFF while your waiting. let it idle to keep the cat and engine warm. Why this is so important is the computer will run on a cold start pre set fuel map when cold and not be using the mixture information provided by the O2 sensor. This is known as open loop operation. It's EFI's version of the choke. A temperature sensor will tell the engine when the coolant is up to operating temp. The computer will then make it's mixture settings using the O2 sensor. This is what's known as Closed loop.
    Many people make the mistake of putting in the wrong thermostats into a efi vehicle and while idiling they will cool down enough that the computer kick out of closed loop. EFI trucks should be running a 190-195 deg thermostat. That's what the EFI was designed to use. If you have a 180 or god forbid a 160 degree thermostat you need to remove it and go back to 190.
     
  4. squirelmurphy

    squirelmurphy Registered Member

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    Location:
    Lakewood, Ca.
    The '78 I just bought passed with flying colors (also in Ca.). Normal tune up stuff, but I also went with a 3" exhaust with a good performing 3" cat and flowmaster muffler. Helped out quite a bit, plus it sounds good.

    I had the muff, but the rest ran me around $300 installed with the cat.
     

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