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Thread: Vauxhal C20xe

  1. #1
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    Default Vauxhal C20xe

    I donít think there are too many Caterhams here in the US who have the Vauxhal C20xe motor but I just bought mine and want hook up with other owners, especially those who enjoy working and upgrading them.
    My first question regards the sensor mounter on the block which is looking at - I think - a missing tooth wheel mounted on the crank. Does anyone know what type sensor this is and what the output is?
    Iím guessing Hall type but ...

  2. #2
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    That is the Crank Position Sensor, aka CPS!
    1987 Caterham 1700 Supersprint
    2002 Porsche Boxster
    2004 Porsche Boxster S
    1941 Dodge Luxury Liner
    2009 Mercedes CLK 350 Cabriolet
    2017 Chevrolet Volt

  3. #3
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    Thanks Anker, any idea what the output is? I am going to eliminate the distributor and didn't really want to install another sensor externally if I didn't have to. Or, is there an information source for this device? Thanks, hr2guy

  4. #4
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    The output is a series of electrical pulses with one missing (where the tooth is missing), It allows the ECU to detect whether the crank is turning and also determine it's position at any point in time because it knows where the missing tooth is. I suspect that is at TDC for cylinder 1. The sensor feeds directly into the ECU.

    An ECU needs a CPS in order to time the ignition and on a fuel injected car also the fuel injectors.

    For the toothed wheel to work with an ECU it must have the number of teeth the ECU is designed for and also have the missing tooth in the correct position. As mentioned above, I suspect they all have the missed tooth in the same position. The number of teeth may be an issue.
    1987 Caterham 1700 Supersprint
    2002 Porsche Boxster
    2004 Porsche Boxster S
    1941 Dodge Luxury Liner
    2009 Mercedes CLK 350 Cabriolet
    2017 Chevrolet Volt

  5. #5
    Join Date
    Dec 2017
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    I believe it is triggering off of a 60 -2 tooth wheel, but I was not able to find or figure out what the position of the sensor is at TDC to use the output to trigger a different ecu (in my case an electromotive wasted spark system). If you find out more in this regard I would be very interested.

  6. #6
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    According to Dave Walker's book, the Bosch 60-2 trigger wheels place the missing teeth at 120 deg BTDC vs. 90 deg BTDC for the Ford 36-1 pattern. I can confirm the latter is correct.

    HR2guy, it's probably an induction sensor, not Hall Effect, which reads a magnet passing over it whereas the induction just needs ferrous metal like the teeth of that trigger wheel. What are you trying to achieve by replacing the distributor? Are you looking for a true 3D system, or do you just want something with reliable electronics that allows you to adjust the shape of the 2D curve? If the latter, you might want to investigate the 123Ignition system. I'm not certain if they have a replacement for the Vauxhall, but if they do, it's plug and play and easy to use. I'm happy with the one I installed in the Elan.

    -John
    '95 Westfield SEiW w/2.0L Duratec
    '68 Lotus Elan FHC
    '91 Miata w/Flyin Miata suspension & brakes
    '95 Porsche 993 C2
    '86 Porsche 944 turbo (neglected project car)
    Throttle Steer

  7. #7
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    Thanks John. You mentioned a book by Walker. Is it available?
    The distributor on the C20xe is non adjustable and for me is immediately suspect. Nothing mechanical lasts forever and I have looked but haven't found much in the books I have for the Vauxhal. I like to have control over ignition for tuning purposes and would settle for a simple 2D curve to begin with. I am going to incorporate a tach and speedo, low oil pressure warning light and generally bring the dash up to current technology. It won't take much to improve what I've got.

  8. #8
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    p.s. I intend to share everything I learn and do with the Vauxhal because a lot of it will be applicable no mater what engine you have.

  9. #9
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    Yes, the book is still available, but not sure how much it will help. Dave is a well known engine tuner in the UK whose company makes the Emerald ECU. It's pretty popular in se7en circles over there and I use one myself, hence the reason I have that book in my library. You can find it here on Amazon.

    Definitely investigate the 123 Ignition. I have the Tune+ version which connects to an iOS or Android mobile device via bluetooth, and features real-time programming, rev limiter, anti-theft, and vacuum advance that can create a pseudo 3D map. That last feature is tough to implement with twin DCOEs though.

    -John
    '95 Westfield SEiW w/2.0L Duratec
    '68 Lotus Elan FHC
    '91 Miata w/Flyin Miata suspension & brakes
    '95 Porsche 993 C2
    '86 Porsche 944 turbo (neglected project car)
    Throttle Steer

  10. #10
    Join Date
    Sep 2020
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    Thanks John, I’ll take a look.

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