In a DEEP hole : ( 1992 Suburban failed emissions

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by notpilbrisk, May 10, 2010.

  1. notpilbrisk

    notpilbrisk Member

    Okay so to begin, just recently had my 1992 Chevy Suburban K2500 5.7l TBI 4x4 in the shop to get inspected. The burban failed emissions bcus of too high count of hydro carbons. The limit for HC's is 537 and the trucks value was 604. I just barely passed the nox test with the limit being 7380 and my trucks value 6931. Not quite sure where to begin to get my HC's to go down. While it was in the shop they tried connecting to my obd computer and got NO communication. Ive tried searching with the search option for how to read blink codes by jumping pins where the connector is plugged in but had no luck. was told by a buddy that it was the bottom row far left two pins that would need to be jumped to get a code. tried doing this with the KOEO but got no blinks. Any suggestions or advice in helping me figure out these problems is greatly appreciated. Im a college student and need my truck to get to school and work to survive. Once again ALL advice is GREATLY appreciated. Love having a community i can go to for advice when working/running into problems with my truck. Thanks guys. annnd girls..
  2. Chris Miller

    Chris Miller Rockstar 100 Posts

    In order to get your blink code, take a paper clip, bend it, and short the top two upper-right-hand connectors on the plug. Put your key in Run. Very simple. :)
    Sounds like you're in need of a major tune-up, especially in the ignition. How old is your coil, module, wires, etc? And how many miles do you have on the truck?
  3. Dr_Zero

    Dr_Zero Epic Member 5+ Years 500 Posts

    Some aviation gas would probably help with the emissions :happy:
  4. notpilbrisk

    notpilbrisk Member

    okay soo my truck has 111,000 on it at about 105000 i did the plugs wires cap rotor. as for the coil it is still the original as far as i know. and the module ? if u could explain wat u mean not quite sure sry. i have put a New fuel filter, air filter, alternator, battery, power steering pump onto the truck along with alot of other suspension stuff. not sure how a tune up with ignition components would help me lower those numbers. . . thanks again for the help.
  5. notpilbrisk

    notpilbrisk Member

    also i was able to get codes 12 and 43 from jumping those pinis is there any where online that interprets these codes. also im confused with how the shop i brought my truck too said they could not communicate with my computer, yet i was able to get those codes. sorta think their pulling my leg here . thanks again Gerry
  6. Dr_Zero

    Dr_Zero Epic Member 5+ Years 500 Posts
    Last edited: May 12, 2010
  7. Looey

    Looey Rockstar

    I googled high HC and copied it here....some interesting reading....

    Just a reminder of what causes different emissions readings and what to do about them--

    A high HC reading is the result of poor combustion. The most typical cause is a poor ignition system. HC is nothing more than fuel that makes it out the tailpipe without being burned.

    So, your first step on the way to compliance will be a complete ignition tuneup: plugs, wires, caps and rotors. These parts are quite reasonable at any of the Big Three suppliers. The only exception to that might be the wires-- still "reasonable" but maybe just a little price shock. Resist the urge to spend on exotic multi-electrode plugs too; their only purpose is to provide extended life on new cars. The Bosch platinums will work just fine. Don't succumb to the temptation to get "bargain" wires either. The care and time required for wire replacement make installing good wires the best investment. Some folks have replaced aging ignition coils as part of the process too, while everything is out and accessible.

    The CO reading tells you about the fuel mixture. For the most part, HC and CO are unrelated, unless the mixture on a cylinder is lean enough to cause a misfire. Lean conditions result from vacuum leaks at hard/cracked/broken hoses, leaking gaskets and boots around MAF/MAS sensors, and partially clogged fuel injectors. Old vacuum and emissions hoses undoubtedly need replacing just due to age on many cars, so getting all new ones and installing them in one session is not a bad way to go.

    A poor oxygen sensor might cause a lean condition severe enough to create a misfire, but an engine with reasonable ignition will easily fire with that slightly lean mixture.

    So, your marching orders would read ignition tuneup as described above, a visual inspection of hoses for vacuum leaks, followed by a listen and spray, and finally a test with a good high-impedance DVM for output from the oxygen sensor.

    You should also be aware that excessive HC passing to the exhaust is death on a catalyst. They are only rated to react a certain mass of fuel, so extra fuel translates to extra heat, which leads to (hopefully just) a failed substrate, but too often also results in a fire. (!!) No matter-- if you have the high HC readings at the tailpipe, new catalysts are in your future if you want to have the car clean. Often, a carefully tuned 928 will pass without catalysts working, so start off with the basics and see how you do in pre-test mode at the smog check station. Then do the cats as your budget allows. You'll breathe easier.
  8. backcountry horsewoman

    backcountry horsewoman Rockstar 100 Posts

    I took my truck to two different shops who told me they couldn't read codes before I learned how to use a paperclip and find out myself. The 12 code is your system telling you it is running the code check. 43 is your knock sensor, and probably not related to your emissions issue.
  9. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    Actually a knock sensor can cause problems, because a bad knock sensor will tell the computer to "richen" up the mix since it is thinking there is spark knock (detonation) which can cause damage to the motor. So i would repair that problem and go from there.
  10. ChevyFan

    ChevyFan The Sheriff Staff Member 5+ Years 1000 Posts

    We need someone to write up all of the codes and post them up here.

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