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What’s a recommended device to measure CO to set idle speed?

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  • What’s a recommended device to measure CO to set idle speed?

    Looking for a cost effective model.
    Link or a name would be great.

  • #2
    Watching this as interested also though I do think for the average user; nothing is as cost effective as taking the car to a classic friendly mot test station who will let you use their kit for 10mins if you do the adjustments. Done that a couple of times and one occasion it was free as the figures were spot on and the other occasion was £10. Both occasions the owners were happy to have a 'proper' car in their garage and you can't argue with the accuracy of mot testing machines...



    • #3
      I didn't think you could adjust co or idle on the S2? I have an old Gunson gas analyser, which is actually pretty accurate for something which cost £40 25 years ago. Using it on my Ur at the moment.
      Nothelle S2 Avant in restoration
      Wr Ur Quattro (also in restoration)


      • #4
        It's ecu controlled so not adjustable unless you are running an aftermarket ecu


        • #5
          Mostly it is ecu controlled but if the setting is way out for some reason, the lambda and closed loop control may not be able to bring it into spec at Idle (14.7:1 air fuel ratio)

          The 7A is adjustable and the process is included in the Bentley manual but involves putting it in set up mode beforehand and returning to lambda control afterwards. Fuse in top of fuel pump relay, wait a couple of seconds, adjust maf and idle air screw accordingly and remove fuse, rev to 2000rpm and back to ecu control again. Putting the fuse in the fuel pump relay removes lambda, ISV and ecu coolant temperature inputs to the ecu.

          What is the engine the cgharibo has?


          • #6
            My engine is a 7A and I have had the car since new. The car is a '91 Coupe that has 250k miles.

            The CO screw on the MAF has never been adjusted.

            A CO gas analyzer suggestion to purchase would be greatly appreciated.


            • #7
              As mentioned, the Gunson or a Hawk would do the job. It probably doesn't need an adjustment. My 7A has never been touched and at the last mot test, the co was so low it barely registered. Miles are way higher than yours



              • #8
                My 7a always impresses the tester at emissions time. No cat fitted to my car and it always returns figures that are not that much more than a cat equipped car.

                As a piece of interesting relevant information; I had cause to test and adjust the CO on mine recently during some tuning work and in set up mode it was reading around 4.5% CO. In normal mode it was back down to around 0.5%. It just goes to show how effective the lambda trimming at idle is. I turned down the MAF screw purely in order to give the lambda less work to do.