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High Hydrocarbon TailPipe test B21 Injector Test? 200 1980

posted by  someone claiming to be sydney on  Sat Apr 12 11:39 CST 2003 [RELATED]

I am getting a high hydrocarbon at idle so failed tail pipe test. The other
tests are ok (co and driving Hydrocarbon under load). It was suggested I check
injector spray. Pulled them out and when cranking over get an occasional good
spray out of them but not steady as would be expected. Maybe because its not
running. Is there a way to fake out the system? Any other ideas of where the
problem might be? The oil flame trap white plastic is not plugged and I do
not seem to have excessive oil consumption.
First time thru with timing about 6 BTDC and adjusted for lean running, I
got driving HC = 57 (max allowed =212) and idle HC= 1092 (max allowed=411)
and CO driving .51 (max allowed 1.46) and idle CO=.25 (max allowed= 4.59)
nox=1008 )max allowed=2125)
I then tried changing timing to factory 10 degrees and richened up mixture
and driving HC=76 and idle HC=1205 ; driving CO=.58 idle co=.25 nox=1188.

As the injectors seem to spray ok when they spray( i assume it must be irregular
when cranking with them all out as it is not running) I am not sure what
to do now. maybe there is a way to fake out the system for a spray test.
Any comments appreciated....sydney








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    Injector spray pattern testing - kjet 200 1980

    uid 27's pic
    posted by  Art Benstein on  Sat Apr 12 11:57 CST 2003
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    last visit: Fri Oct 17 20:10 CST 2014
    [RELATED]

    Haven't tried this myself, but I understand you just need to jump around the fuel pump relay to run the pumps with the engine off. Then, to test the spray, with the throttle body to air-fuel unit hose removed, lift the airflow plate.
    --
    Art Benstein near Baltimore








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      Injector spray pattern testing - kjet 200 1980

      posted by  someone claiming to be sydney on  Sat Apr 12 14:57 CST 2003 [RELATED]

      Thanks for the tip, Art. I have subsequently had all the injectors out and
      seem to get the occasional good spray out of all of them when the engine is
      first cranked over as if starting. Also checked the starting injector or cold
      start injector or whatever the proper term is, and it is not dripping or leaking
      when the engine is running. I am sort of perplexed as
      to where the extra fuel fuel or oil is coming from. Incidentally the injectors
      are new about 3 years ago and maybe 30K km since then.
      Not sure if it is worth geting into the wiring of the relays when I see decent
      spray. I am kind of suspicous of the fuel distributor either letting too much
      through at idle or maybe leaking into the throttle body and carrying the fuel
      in that way....hopefully someone who has experienced this may comment. syd








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        Injector spray pattern testing - kjet 200 1980

        uid 27's pic
        posted by  Art Benstein on  Sat Apr 12 15:41 CST 2003
        Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
        last visit: Fri Oct 17 20:10 CST 2014
        [RELATED]

        I figured you were looking for an injector opening at too low pressure. Getting the injectors out and into jars is more than half the task. The relay is just pulled from its socket and a wire or paper clip used to connect terminal 30 and 87 to bring the pumps on. My 79 does not have lambda so I can't tell from experience how to troubleshoot mixture as adjusted by the frequency valve-- all I have is the 3mm hex adjustment on the airflow meter, without any good means of measuring the effect. I wonder if the state emissions testers passed it out of pity.

        Other than the way you are pursuing it the only test I could suggest is measuring the line and control pressures.
        --
        Art Benstein near Baltimore








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          Injector spray pattern testing - kjet 200 1980

          posted by  someone claiming to be sydney on  Mon Apr 14 10:06 CST 2003 [RELATED]

          Thanks for the procedure for the injector testing, Art! I will file that away
          for future use. I did check the CIS sensor plate for height adjustment and it
          was ok. What I did find was a cracked vacuum hose that goes between the
          Auxiliary Air Valve and the manifold. It seems that replacing the hose and
          slightly retarding the timing resolved the high HC readings. Thanks again for
          the assistance !! Syd.








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            Injector spray pattern testing - kjet 200 1980

            uid 27's pic
            posted by  Art Benstein on  Mon Apr 14 12:37 CST 2003
            Author: [PROFILE] [EVERY POST] [THREADS] [BEST POSTS] RSS Feed     [IGNORE ALL POSTS]
            last visit: Fri Oct 17 20:10 CST 2014
            [RELATED]

            "...slightly retarding the timing resolved the high HC readings." This is a trick that seems to guarantee passing the tests. I'll bet the vacuum leak had the opposite effect if it was high in HC.

            As to the injector testing, one of the books has a picture of four clear graduated cylinders with injectors stuck in them to test pattern and volume. I think for most of us this it is peanut butter jars.

            Congratulations on passing the test!
            --
            Art Benstein near Baltimore







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