prelude1980
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| posted on 18/11/07 at 09:00 AM |
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Acewell Speedo Problem
I have done a search but to no avail before someone says it
i can drive along and the speedo readings correctly when i let off the accelerator the reading drops in half but when on the speedo it corrects
itself.
I have seen the answer to this somewhere but i can't remember where
Any help appreciated
Speed has never killed anyone. Suddenly becoming stationary... that's what
gets you.
https://www.topcashback.co.uk/ref/dodd1980
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Macbeast
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| posted on 18/11/07 at 09:05 AM |
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Maybe some flexing causes the sensor position to alter slightly when under power and on overrun ?
Just a guess
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prelude1980
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| posted on 18/11/07 at 09:07 AM |
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not a bad suggestion but the sensor doesn't have any movement in it.
Speed has never killed anyone. Suddenly becoming stationary... that's what
gets you.
https://www.topcashback.co.uk/ref/dodd1980
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Paul TigerB6
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| posted on 18/11/07 at 10:01 AM |
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quote:
Originally posted by prelude1980
not a bad suggestion but the sensor doesn't have any movement in it.
Your engine / transmission may be moving slightly affecting the readings though. Where abouts have you got the sensor mounted??
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prelude1980
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| posted on 18/11/07 at 12:31 PM |
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my magnets are mounted on the diff flange, the diff is solidly mounted.
I think the problem is electrical, something to to with the voltage but i'm not sure
Speed has never killed anyone. Suddenly becoming stationary... that's what
gets you.
https://www.topcashback.co.uk/ref/dodd1980
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flange nut
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| posted on 18/11/07 at 05:57 PM |
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I really can't see this being electrical. What sort of gap have you got between the sensor and magnets?
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prelude1980
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| posted on 18/11/07 at 06:47 PM |
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about 2mm gap. i can only see electrical because lifting off the accel pedal very lightly it does it. seems to be when engine under load and not this
happens
Speed has never killed anyone. Suddenly becoming stationary... that's what
gets you.
https://www.topcashback.co.uk/ref/dodd1980
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the_fbi
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| posted on 18/11/07 at 07:40 PM |
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What is the sensor mounted to?
Any photo's showing the install?
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Macbeast
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| posted on 18/11/07 at 07:57 PM |
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Straw grasping .....
Let's say your sensor cable is picking up some interference from the ignition. When under load the ignition is in time with the sensor signal.
When you take your foot off, ignition should advance (I think - the timing will change anyway ) and the interference will cancel the sensor signal or
at least confuse it.
I would make sure sensor signal is thoroughly screened.
Is this a problem that has suddenly appeared on a car that was working OK before or is it a new installation ?
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prelude1980
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| posted on 18/11/07 at 08:09 PM |
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this is a new install. didn't think of screened cable and interference, but would this still happen if the wires didn't go near the front
of the car
Speed has never killed anyone. Suddenly becoming stationary... that's what
gets you.
https://www.topcashback.co.uk/ref/dodd1980
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Macbeast
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| posted on 18/11/07 at 08:15 PM |
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I get interference from mopeds in the street and I'm on the third floor 
Maybe worth a try then - I'm sure I've seen screening recommended here in previous topics.
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flange nut
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| posted on 18/11/07 at 11:27 PM |
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Does the speedo start to read correctly as the car's speed has reduced a lot? What happens if you declutch and rev the engine? Have you got
the magnet polarity the right way round? I suspect that the sensor to magnet gap is increasing when you take your foot off the gas. I would
reduce the sensor gap a little if you feel it's safe.
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