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    Thread: Adjusting mixture

    1. 05-22-2020 09:59 AM #1

      I'm working on a 1986 cabriolet with CIS engine. I recently replaced the injectors with new Bosch, injector holders, fuel filter, air filter and plugs and was hoping to adjust the fuel mixture since the adjustments was setup for the previous injectors (were shooting fuel like a water gun).

      When I plugged in my Dwell/Duty cycle meter, I measured a very high and constant 86.5%... When I unplugged the single wire O2 sensor, the meter reported a nice 50.1%.

      Would you say that it is an indication of a bad o2 sensor or is it because the mixture is set extremely lean and switches to an enriched mixture when I unplug the O2 sensor?

      Currently, the engine has a solid idle but hesitations under load while driving..

      Fairly new with this very interesting CIS system - learning as I go. I appreciate your help!

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    3. 05-22-2020 12:02 PM #2
      Sounds like the Lambda system is working well. Adjust the Lambda till it reads around 50%. The engine should be plenty hot.

    4. 05-22-2020 01:46 PM #3
      I turned the mixture adjustment about an 8th of a turn clockwise last night, heard a small change in idle but the meter remained solid at 86.5 - I'll try turning it a bit more tonight. The fact that it is a constant 86.5 but becomes variable at 50.1 - 49.8 with the O2 sensor unplugged makes me believe that something is not working right..

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    6. 05-23-2020 09:54 AM #4
      Something is not adjusted right, but it appears to be working properly.

      There are many people in the world that should not be under the hood of their car. Americans believe they should be able to fix their car and sadly, most have no clue. This is probably what happened. Someone was under the hood making adjustments without the knowledge or tools to make them correctly.

      Your lambda seems to be working. That is a good thing. If the lambda is adjusting the idle and it's at 80%, then try getting it to adjust to 50%. You'll need more turns than and 1/8th. If it makes you happy, count then number of turns. Make certain you do not leave the tool engaged. Make an adjustment and take it back out again.

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