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High HCs at Idle

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  • #580216
    Sam VarnerSam Varner
    Participant

      My 02 Kia spectra failed California smog with High HCs at Idle – HC’s measured 157 (Max: 100; Average: 17); CO measured 0.77 (Max: 1.0; Ave: 0.0). Tomorrow, I plan on changing the oil, filters, plugs, plug wires and look for vacuum leaks. Suggestions/alternatives will be appreciated. Besides paying for another smog, is there a way to check the hydrocarbon measurements?

    Viewing 15 replies - 1 through 15 (of 25 total)
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    • #580228
      WayneWayne
      Participant

        Are you noting any issues performance wise? Don’t suppose they gave you a readout?
        http://www.crypton.co.za/Tto%20know/Emissions/exhaust%20emissions.html

        High HC, low CO, and high O2 at same time indicates a misfire due to lean or EGR diluted mixture

        High HC, high CO, and high O2 at same time indicates a misfire due to excessively rich mixture.

        High HC, Normal to marginally low CO, high O2, indicates a misfire due to a mechanical engine problem or ignition misfire

        Normal to marginally high HC, Normal to marginally low CO, and high O2 indicates a misfire due to false air or marginally lean mixture

        As to measuring HCs without a sniffer, not that I’m aware of. A canary, coal miner style might do it, but you’d need a baseline to start, so you’d need 2 canaries, and not let PETA know. 😉

        #580260
        Sam VarnerSam Varner
        Participant

          I did have a mis-fire code and some hesitation but found the found the #1 plug wire corroded. After cleaning, it’s running great now. Other than the Vehicle Inspection Report, don’t have a readout. Thanks so much for your help and email.

          #580268
          WayneWayne
          Participant

            I really don’t have that much emission insight, just basic knowledge, but seems that’s on the higher end of CO emissions coinciding. So were it me, I’d assume a rich condition at least initially if you have no live data scanner access. You’re on the right track, but if you don’t find an intake or exhaust leak (I’d check for both) I’d probably throw a new primary OEM 02 sensor at it, clean the MAF sensor, and reset the stored fuel trim mappings before the next run just to give myself the best odds (just yank negative battery terminal long enough for ECU/PCM to lose it’s volatile memory, a few minutes will make it a near certainty). The idea being it may be storing long-term fuel trim data that’s either incorrect, or just averaged at a certain load a bit rich over time, this will reset the long-term fuel trims to 0 to force the short-term to deal with the rich and lean conditions it senses for a time.

            If you have a decent scanner that can do live data, or have a friend with one, viewing the short and long term trims will give you a better idea. With CA emissions, it doesn’t take much to fail.

            #580305
            Lorrin BarthLorrin Barth
            Participant

              Maybe the cat is shot.

              #580312
              WayneWayne
              Participant

                Should be NOx emission failure were this the case I believe. Although they may not have tested for it, if the substrates are near shot I believe the normal rich to lean cycling could cause the HC emissions failure.

                #580322
                Sam VarnerSam Varner
                Participant

                  Thanks for all the input. This is great stuff for a fly-by-internet mechanic. I have an Innova 3100e Scanner. It may display live data — I’ll read up on viewing the short and long term trims.

                  Here are the complete Idle Emission Test Results: Low Idle: @ 799 RPM %CO2 MEAS 10.9; %O2 meas 4.8; HC (PPM) Max-100, Ave-17, MEAS 157; CO (%) Max-1.00, Ave-0.0, MEAS 0.77 – FAILED. High Idle: @ 2584 RPM %CO2 MEAS 13.8; %O2 MEAS 0.7; HC (PPM) Max-130, Ave-12, MEAS 33; CO (%) Max-1.00, Ave-0.1, MEAS 0.51 PASSED.

                  I’ll read up on my scanner capabilities. Again, thanks to all…

                  #580457
                  EricTheCarGuy 1EricTheCarGuy
                  Keymaster

                    High CO and HC indicate a rich mixture. The most common cause is a misfire or incomplete combustion. You might consider replacing that plug wire along with the rest of them and also replace the plugs at the same time and then recheck the results. More information here.

                    http://www.ericthecarguy.com/faq/solving-automotive-performance-issues

                    Keep us posted on your progress.

                    #580678
                    Sam VarnerSam Varner
                    Participant

                      My plugs and wires all appear relatively new. It appears the one wire corroded due to pressure washing the engine compartment. In either case, I’ll likely replace the wires. But before doing so, I’d like comment on the issue as well.

                      Before entering the fuel rail, fuel passes through the Fuel Pulsation Damper (FPD) on the Kia. My FPD is leaking at cold start-up or when the key is turned to accessory (starting the fuel pump). After the vehicle has started and ran for a few minutes or when started during the heat of the afternoon (>70o), the FPD does not leak. I’ve replaced the FPD with a used one and it leaks too. I have a new FPD but am reluctant to install for fear it will leak too making it non-refundable. Any thoughts on what could be causing my FPD to leak? Also, could this be contributing to my failed smog?

                      Appreciate all the great feedback. Keep it coming…

                      #580683
                      Lorrin BarthLorrin Barth
                      Participant

                        I wouldn’t want gasoline leaking any place but particularly under the hood. For that reason alone I would replace the part.

                        #581026
                        Sam VarnerSam Varner
                        Participant

                          Well, I replaced the Fuel Pulsation Damper with a new one yesterday. No leaks this morning. Yea! I’ve tuned it up replacing the fuel filter, plugs, wires, oil filter, air filter, oil and have cleaned the MAF sensor. I also installed the missing heat shield of the upper catalytic converter. I pulled both O2 sensors off my parts car and installed them. My scanner’s flashing C indicating the vehicle hadn’t completed the “run test” has not cleared. Yet, I’m now getting a flashing EV indicating the run test is not complete for the Evaporative System. I’d like to take it in for a smog today but am concerned the EV has not completed it run test. All other run test have completed. I sure appreciate all comments. You’ve been most helpful.

                          #581160
                          Lorrin BarthLorrin Barth
                          Participant

                            Go for a drive on the highway for say 30 miles. Try to maintain a steady speed. Then check again.

                            #581208
                            Sam VarnerSam Varner
                            Participant

                              My re-test for smog is scheduled in an hour or so. I’ll let you know the outcome. In my last post, I meant to say, My scanner’s flashing C indicating the vehicle hadn’t completed the “run test” has cleared. I’ve driven nearly 200 mile since the tune up and that annoying flashing “EV” is still present. My smog guy says he’s seen them taking weeks to clear the run test.

                              #581305
                              EricTheCarGuy 1EricTheCarGuy
                              Keymaster

                                I’m glad you fixed the fuel leak. You do realize that leaking fuel can give high HC readings. Not to mention it’s a fire hazard. When you have known problems like that, address them first. This way you can eliminate known issues from the equation.

                                Keep us posted on how your test goes and good luck.

                                #581678
                                Sam VarnerSam Varner
                                Participant

                                  Well, it failed again. The tune up and fixing the fuel leak by replacing the Fuel Pulsation Damper with a new one made absolutely no improvement to the HC’s (went from 157 ppm to 156 ppm). As it turns out, the Cat was completely shot. The honeycomb substrate in the Cat was completely gone. I replaced the Cat. My smog guy sniffed it for me yesterday and said it’s, “clean as a whistle.” I have an appointment to retest in an hour. Wish me luck. I’ll let you know the outcome.

                                  #581823
                                  EricTheCarGuy 1EricTheCarGuy
                                  Keymaster

                                    Thanks for the update and good luck. The cat itself won’t cause high HC and CO. Catalytic converters are designed to reduce NOx emissions. What was likely happening is that it was causing a restriction in the exhaust causing the engine to work harder and not be efficient.

                                    Keep us posted.

                                  Viewing 15 replies - 1 through 15 (of 25 total)
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