'93 ZX twitchy speedo and wavy revs?

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Jason Arthurs - 06 Mar 2006 09:47 GMT

The speedo dial on my ZX has an annoying twitch, which makes telling
the speed below about 50mph a very hit and miss affair. Upto 50mph the
needle constantly wobbles buy around 10% of the current speed. So at
40mph it wavers between 40 and 44mph, and at around 50mph it finally
stabilises and reads a constant speed (albeit about 10% faster than
the speed reported by my GPS unit).

Also at higher speeds the rev counter periodically does a full wave
from redline, to zero and back to the correct reading.

From memory it's done this for around 30,000 miles, and I'm just
curious rather than concerned...

Regards,
Jason.

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Adrian - 06 Mar 2006 10:11 GMT

> The speedo dial on my ZX has an annoying twitch, which makes telling
> the speed below about 50mph a very hit and miss affair. Upto 50mph the
> needle constantly wobbles buy around 10% of the current speed. So at
> 40mph it wavers between 40 and 44mph, and at around 50mph it finally
> stabilises and reads a constant speed (albeit about 10% faster than
> the speed reported by my GPS unit).

Speedo cable.

> Also at higher speeds the rev counter periodically does a full wave
> from redline, to zero and back to the correct reading.

What engine? Petrol or diesel? Sounds like an iffy connection somewhere.

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Seany - 06 Mar 2006 12:34 GMT

My '93 ZX est. 1.9D did exactly the same thing.
It turned out to be a faulty connection on the sender unit, which I believe
is connected to the gearbox somewhere, IIRC....

Never did have mine fixed as I traded in for a bigger car and it never
really bothered me tbh.

> The speedo dial on my ZX has an annoying twitch, which makes telling
> the speed below about 50mph a very hit and miss affair. Upto 50mph the
[quoted text clipped - 15 lines]
> Replace nntp with my name to reply.
> N0 5pAm H3r3: Include this tagline to pass my spam filter.

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Malc - 06 Mar 2006 21:11 GMT

>> The speedo dial on my ZX has an annoying twitch, which makes telling
>> the speed below about 50mph a very hit and miss affair. Upto 50mph the
[quoted text clipped - 8 lines]
>> From memory it's done this for around 30,000 miles, and I'm just
>> curious rather than concerned...

> My '93 ZX est. 1.9D did exactly the same thing.
> It turned out to be a faulty connection on the sender unit, which I
> believe is connected to the gearbox somewhere, IIRC....
>
> Never did have mine fixed as I traded in for a bigger car and it never
> really bothered me tbh.

My 1.9TD Xantia did exactly the same and yes, it was the sensor. My local
specialist fitted a s/h sensor for about £2 and £10 labour or something
equally miniscule and did it while my wife waited. Presumably the rev
counter may be similar or does it get its info from somewhere else.

FWIW my speedo eventually failed and the original specialist I took it to
diagnosed a duff speedo although the immobiliser had also failed. It turns
out (as the specialist I now use told me) the fuse for the imobiliser also
fed the speedo sensor. Anyway in between finding the second chap I drove the
car for a year without a speedo because I had the foresight to remember the
rev counter readings for various speeds.

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Malc

"It is inconceivable that anything should be existing. It is not
inconceivable that a lot of people should also be existing who
are not interested in the fact that they exist. But it is
certainly very odd."

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