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Thread: I'm getting values between 8.0:1 and 9.0:1 at idle and part throttle on my wideband a

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    Bodger mario r h santos's Avatar

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    I'm getting values between 8.0:1 and 9.0:1 at idle and part throttle on my wideband a

    I'm getting values between 8.0:1 and 9.0:1 at idle and part throttle on my wideband afr gauge...

    To give a little context, it's an almost full race engine, running 45's dhla, ht1e, forged pistons, bigs valves, and compression ration of about 12.0:1.

    I mean, the car runs perfect, no smoke, picks up very quickly and sounds healthy, holds idle at around 6/700 rpm (seems low to me but it picks up so well... that I don't judge it a lot). Revs quite well. It's still bedding in. Haven't put much miles on it yet and haven't yet passed the 6000 rpm limit.

    At full throttle the afr is on low 14's.0:1 which sounds good to me but at idle I can't help but be a bit nervous. Don't want to blow the piston rings too soon.

    I can state the carb settings if needed later on.

    Any sugestions? Can I live with this? Should I change something?

    This week I'm going to take the plugs and post some pictures. Maybe that'll help.

    Cheers and thanks,

    Mário Santos.

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    Re: I'm getting values between 8.0:1 and 9.0:1 at idle and part throttle on my wideba

    14:1 at full throttle is too lean, between 8:1 and 9:1 at part throttle is too rich.
    Where have you mounted the lambdasensor?
    Have you connected the internal heater?

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    Re: I'm getting values between 8.0:1 and 9.0:1 at idle and part throttle on my wideba

    Its idling so low probably because its drowning and its revvy because its lean - old 2 stroke race bikes were tuned by feel - get the sharpest pick-up you could then richen it a couple of numbers - race like it was and it'd seize guaranteed! Ideal WOT AFR number range 13.2 - 12.5. And a 'full race' engine won't idle steady unless the flywheel is huge.............then its not 'full race'
    Last edited by katana; 28-05-2017 at 18:36.

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    Re: I'm getting values between 8.0:1 and 9.0:1 at idle and part throttle on my wideba

    I have a very similar spec of Pinto with an Innovate AFR meter fitted, off cam and at idle it will always run very rich, its more than likely the lambda sensor is being flooded with the very rich mixture, even with a probe heater on the same will happen, i re-mounted my lambda probe to a more vertical position and the readings went from 9:1 to around 11. With that same cam, compression and 48's with 40mm chokes i found best power / torque at 12.5 - 13.5 : 1, 13.5 being the leanest reading at the top part of the rev range. My idle speed is approx 1100rpm but even that requires constant tuning to run smooth. Running under 3000rpm will never be smooth with an HT1e. I have however managed to get mine to pul very smoothly on a light throttle from 2000rpm by properly tuning the idle to main circuits. what are your carb jet sizes?
    Last edited by Erikmex; 29-05-2017 at 08:59.

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    Re: I'm getting values between 8.0:1 and 9.0:1 at idle and part throttle on my wideba

    Erikmex, I was about to put the link from a previous post of yours. Here (so the other participants can get in context): http://www.turbosport.co.uk/showthread.php?t=771201

    You got me there! I was figuring out exactly the same thing you told me! My sensor is horizontally located at the end of my exhaust manifold at 90 degrees. At which angle is yours? What do you suggest? I've got to start troubleshooting this and try everything before starting to change carb parts as it runs so perfect.

    Miniliteman, in terms of wires the lambda kit was quite simple. Sensor has a cable that connects to the ecu which connects to the gauge and power. I don't know how it could be connected without the heater being on.

    Katana, according to my Mec., it's idling so low because he figured the engine could handle it well. It has a lightened flywheel but only by 0,6 or 0,7Kgs. Not much as you can see. But I got an alloy one sitting in the shelf, waiting for his chance to jump in. Just a matter of time. As I told you before ''it's an almost full race engine''. I didn't want to lose completly the driveability at low speeds as it's intended do hill climbs and not just circuit racing.

    Any more thoughts?

    Cheers and thanks guys,

    Mário Santos.

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    Re: I'm getting values between 8.0:1 and 9.0:1 at idle and part throttle on my wideba

    Mine used to be fitted at 90deg when i had very rich readings, the mounting boss in which it sits can still collect liquids in that position, it now sits around 80-85 degrees, mounting slightly off the horizontal cured the problem, i actually just rotated the exhaust pipe slightly, they are very accurate the readings of mine were very close to the calibrated AFR meter when my car was on the rolling road. I also use mine for hillclimbs and sprints with a light (4.5kg) flywheel, with this spec of engine you really need it to rev quickly to bring it into the strong powerband often a heavy flywheel can reduce drive-ability at low speeds holding the revs in the boggy band!

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    Re: I'm getting values between 8.0:1 and 9.0:1 at idle and part throttle on my wideba

    Quote Originally Posted by mario r h santos View Post
    Erikmex, I was about to put the link from a previous post of yours. Here (so the other participants can get in context): http://www.turbosport.co.uk/showthread.php?t=771201

    You got me there! I was figuring out exactly the same thing you told me! My sensor is horizontally located at the end of my exhaust manifold at 90 degrees. At which angle is yours? What do you suggest? I've got to start troubleshooting this and try everything before starting to change carb parts as it runs so perfect.

    Miniliteman, in terms of wires the lambda kit was quite simple. Sensor has a cable that connects to the ecu which connects to the gauge and power. I don't know how it could be connected without the heater being on.

    Katana, according to my Mec., it's idling so low because he figured the engine could handle it well. It has a lightened flywheel but only by 0,6 or 0,7Kgs. Not much as you can see. But I got an alloy one sitting in the shelf, waiting for his chance to jump in. Just a matter of time. As I told you before ''it's an almost full race engine''. I didn't want to lose completly the driveability at low speeds as it's intended do hill climbs and not just circuit racing.

    Any more thoughts?

    Cheers and thanks guys,

    Mário Santos.
    When the heater isnt working they come up with an error code.

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