Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Emissions Suck

Discussion in 'The Garage' started by RatMan, Dec 12, 2002.

  1. RatMan

    RatMan 1/2 ton status

    Joined:
    Jul 27, 2002
    Posts:
    270
    Likes Received:
    0
    Location:
    Marietta, Georgia
    well, this afternoon i went in to get my emissions inspection done. everything was fine until the guy got out and told me i failed it /forums/images/graemlins/mad.gif. i was just like WTF? he said too much nitrogen oxides. i dont get it, its a pretty much stock truck /forums/images/graemlins/confused.gif. it has an exhaust system, but ewverything is intact (or so i thought). anyway i have 30 days to get it fixed. he said it was most likely the cat or the o2 sensor. is either of these prone to failure? also, what do yall think itll cost to fix it?
     
  2. heavy4x4

    heavy4x4 1/2 ton status

    Joined:
    Aug 28, 2002
    Posts:
    3,270
    Likes Received:
    0
    Location:
    Delafield, Wisconsin
    If you've got a high NO (nitrogen oxide) count, that means your cat isn't doing a good enough job filtering them out. Replace the cat....aftermarket ones can be found for less than $50 (I think)...but original replacements are expensive.
    If it were O2 sensor...that means you're either going to be running rich or lean. Since NO count was high, I would say just replace the cat and leave the O2 sensor alone - but it wouldn't hurt to replace it for performance/mileage gains.
    Good luck on your next go-around. /forums/images/graemlins/wink.gif
     
  3. VisionxOrb

    VisionxOrb 1/2 ton status

    Joined:
    Oct 10, 2001
    Posts:
    251
    Likes Received:
    0
    Location:
    Newbury Park, Ca
    Also make sure the EGR valve is operating normaly. NOx is caused by high heat and pressure inside the combustion chamber. when the EGR is putting the exhaust gas back through it doesnt really burn and the combustion chamber temp drops lowering the NOx count.
     
  4. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

    Joined:
    Mar 5, 2001
    Posts:
    15,680
    Likes Received:
    1,391
    Location:
    642 Days to BB2018
    Maybe an obvious one, but make sure the truck is nice and HOT before you pull in for the sniffer test. The cats work most efficiently when they are at operating temperature...it may be that your cats are fine, they just weren't hot enough to filter properly.

    Just my .02 (and I do take PayPal!)
    /forums/images/graemlins/rotfl.gif
     
  5. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

    Joined:
    Feb 17, 2000
    Posts:
    7,385
    Likes Received:
    0
    Location:
    Atlanta
    Did you get it good and HOT before taking it in there? What temp Thermostat you got in the pig?
    O2 Sensors should be replaced every 60K.

    If you just fired up your truck and drove a couple miles then the cat and engine were not hot. If the engine was not hot or had to cold of thermostat in it the computer would be in "Open Loop". That means the computer is running on a preprogramed fuel curve till the O2 Sensor get up to temp as well as the engine temp. If FI's version of a choke. That truck should have a 195 degree thermostat. The truck may never go into Closed Loop with a 180 degree thermostate.
    Normal tune up stuff can also cause this. Bad plug wires, fouled plugs, etc.
    I always make a pont to run down the hwy for a few minutes like from chastain and 575 up to Hwy 92 and back. I run some super in it for a few day's before the test. NEVER shut down the truck while you wait. Let it idle to keep heat in the cat till it's your turn to be tested.
    Emissions is BS and there is a lot of DUMB things that can cause you to fail.
    If it fails after a O2 sensor and a general tune up.....PM me and I am aware of a guy at a emmisions test point /forums/images/graemlins/wink.gif
    BTW a lot of time if the station is slow you can get them to do a quick un official test to make sure it's right before doing the one that counts. Bassicly the tester CAN shut down the test if he see's it's going to fail BEFORE it fails and it won't count as far as the Clean air force is concerned. He may want a $20 because you took up his time but it will save you from having to deal with the big testing station..
     
  6. heavy4x4

    heavy4x4 1/2 ton status

    Joined:
    Aug 28, 2002
    Posts:
    3,270
    Likes Received:
    0
    Location:
    Delafield, Wisconsin
    Grim - got a question for you.
    I don't recall that the o2 sensor was ever replaced on my truck (160,--- miles). I put a wrench on it at one point to see if it was going to be easy to replace (nothing is easy to replace on my truck...wisconsin). My question is...o2 sensors are standard thread, right? Righty-tighty, lefty-loosy. Also, are they accessible from the engine compartment? There's hardly any room to get a wrench on it under my truck, let alone turning the wrench. Thanks.
     
  7. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

    Joined:
    Feb 17, 2000
    Posts:
    7,385
    Likes Received:
    0
    Location:
    Atlanta
    Yep standard thread. Most are 14mm. Usualy stuck real good if it's orignail. Be sure to use some anti Siez when you put the new one in . Don't own a GM truck with GM FI so not sure if you can get at it from the top.
     
  8. RatMan

    RatMan 1/2 ton status

    Joined:
    Jul 27, 2002
    Posts:
    270
    Likes Received:
    0
    Location:
    Marietta, Georgia
    it was definitely warmed up, she'd been runnin for a good 45 minutes. oh well. i plan on replacing the o2 sensor and probably the cat. BYW, if i get i high-flow cat a) will i still be able to pass (next time) and b) will it make my truck louder? well see what happens. /forums/images/graemlins/laugh.gif
     
  9. RatMan

    RatMan 1/2 ton status

    Joined:
    Jul 27, 2002
    Posts:
    270
    Likes Received:
    0
    Location:
    Marietta, Georgia
    i have no clue what the temp thermostat i have in it. is there anyway to tell? just bought this truck six months ago and still havent figured out whats up to be replaced/
     
  10. 89poohbear

    89poohbear Registered Member

    Joined:
    Jan 4, 2002
    Posts:
    8
    Likes Received:
    0
    Location:
    Colorado Springs, CO
    I failed emissions with a HC PPM score of 222 out of a max 220. Any thoughts as to what to do to fix this? I just bought the truck.
     
  11. creampuff90k5

    creampuff90k5 1/2 ton status

    Joined:
    Feb 15, 2002
    Posts:
    142
    Likes Received:
    0
    Location:
    New Jersey
    I have to pass emisions with my '90 K5 every year and it is a pain in the @ss, but one thing I have learned is to change the oil and install fresh spark plugs right before the test. This helps a TON. Also, when you get real close to the testing facility, pull over somewhere and remove the air filter - just the paper element inside, not the whole assembly - and run the test without it.

    These simple tweaks really do work and I would at least try them before throwing parts and $$ at your truck. I have nearly 200K miles on the original cat & O2 sensor and NJ is a very tough state to pass. As others have suggested, letting things get hot will help too.
     
  12. RatMan

    RatMan 1/2 ton status

    Joined:
    Jul 27, 2002
    Posts:
    270
    Likes Received:
    0
    Location:
    Marietta, Georgia
    okay, heres what i learned

    1. make sure the truck is up to operating temperature - by this i mean drive a good 30 - 40 miles. just get on the freeway and HAUL ASS. go straight to the testing afterwards. dont stop the car anymore than necessary and DONT turn it off.

    2. fill up and run down at least half ur gas tank - get a lot of crap outa the system

    3. run 'cheap' gas. lowest octane rating u can find

    4. most of all, make sure ur truck runs like it should. everything should be in good shape, down to the last detail. it doesnt have to be immaculate or new, just in good shape - not too old or worn at all.

    5. be nice to the guys that work at the testing spot. this wont help u pass (theres not too much they can do to help) but most of em are pretty cool. plus, next time, they might let u do a 'fake' test first to make sure u pass the real one.

    hope that helps some /forums/images/graemlins/grin.gif thats all based on personal experience. i dont have to much, but i did take my test three times /forums/images/graemlins/eek.gif before i passed and did lots of research on what helps /forums/images/graemlins/grin.gif
     
  13. georgiared84

    georgiared84 1/2 ton status

    Joined:
    Sep 5, 2002
    Posts:
    487
    Likes Received:
    0
    Location:
    Austell, Georgia
    Hello Grim,
    Got another georgia emmisions question for you. In Georgia, do they do any type of an under the hood inspection, or just sniffer, cat, etc...?
    BTW, to answer the first question, I agree with the new cat. Had the same prob a few years ago with my 83 and the new cat. fixed it. But check your egr movement first. It always sucks to buy parts you don't need.
     

Share This Page