Discussion
No, I'm not having trouble with my budgie smugglers... 
At Snetterton today, first time out in earnest on track I noticed that, as soon as I lifted off the throttle, the indicated speed dropped by 40 mph. This then progressed to no speed indicated for over half of each lap.
Changed the 100 amp fuse (which was a joy with a red hot sump....not!).
No different.
Any thoughts? What can I try next? If I have a loose wire that is making intermittent contact, where would it be?
At Snetterton today, first time out in earnest on track I noticed that, as soon as I lifted off the throttle, the indicated speed dropped by 40 mph. This then progressed to no speed indicated for over half of each lap.
Changed the 100 amp fuse (which was a joy with a red hot sump....not!).
No different.
Any thoughts? What can I try next? If I have a loose wire that is making intermittent contact, where would it be?
The speedo transducer is fitted on the diff. Yours is a later car so it has the one in the link. As you can see it is adjustable. Maybe disconnect, clean the connector and check the gap as specified in the link, noting the warning! If you can make the gap smaller without possibly damaging it, this may help to give a better signal.
https://tvr-parts.com/tvr-parts/part-details/tvr-m...
https://tvr-parts.com/tvr-parts/part-details/tvr-m...
And it's the same one as fitted to mine.
It's surprisingly easy to remove Anthony, trace the wire back to connector and disconnect it first, then losses the locking nut and spin the sensor out.
It's on the right hand side of the diff at the back
Try adjusting it first though maybe.
It looks like it works the same way with a toothed trigger wheel and sensor as our Ecu with thrigger wheel on crank.
It's surprisingly easy to remove Anthony, trace the wire back to connector and disconnect it first, then losses the locking nut and spin the sensor out.
It's on the right hand side of the diff at the back
Try adjusting it first though maybe.
It looks like it works the same way with a toothed trigger wheel and sensor as our Ecu with thrigger wheel on crank.
Took the car for a test drive to a Sainsbury's and back.....we had run out of tomato ketchup, like you do with kids in da house.
Speedo worked perfectly, from following a Fiesta at 18 mph for a mile, to getting past it at more mph. I also tested that the turbo was working.
So I am now officially baffled.
Though I did get under the car while it was on the trailer this afternoon (makes a good inspection ramp, my trailer, as there is a 3 foot gap between the car treads) and pressed the plug firmly in and fiddled with the wiring near the diff. Maybe I fixed it. No idea, as usual.
Speedo worked perfectly, from following a Fiesta at 18 mph for a mile, to getting past it at more mph. I also tested that the turbo was working.
So I am now officially baffled.
Though I did get under the car while it was on the trailer this afternoon (makes a good inspection ramp, my trailer, as there is a 3 foot gap between the car treads) and pressed the plug firmly in and fiddled with the wiring near the diff. Maybe I fixed it. No idea, as usual.
Bit of a long-shot but could it be possible that the diff is moving slightly thus increasing the gap and thus the affecting readings?
Of course, it could move and reduce the gap, or even connect with the sensor, which wouldn't help
Hard driving on track might just generate a fraction more movement than slightly less spirited road driving.
Another thought, depending on which fuse box you have, reversing light and something else, which I forget, is supplied via same fuse (10A from memory).
I suppose it's also possible that it's the speedo playing up. It's difficult if it's intermittent, but speedometer and odometer stopping tends to point to speedo fault, speedo on it's own tends to point to sensor/transducer. (Actually other way around, see post below)
Just some food for thought.
Of course, it could move and reduce the gap, or even connect with the sensor, which wouldn't help
Hard driving on track might just generate a fraction more movement than slightly less spirited road driving.
Another thought, depending on which fuse box you have, reversing light and something else, which I forget, is supplied via same fuse (10A from memory).
I suppose it's also possible that it's the speedo playing up. It's difficult if it's intermittent, but speedometer and odometer stopping tends to point to speedo fault, speedo on it's own tends to point to sensor/transducer. (Actually other way around, see post below)
Just some food for thought.
Edited by tonys on Friday 25th August 10:24
Thanks Tony
I am thinking and feeding.
I will pass the thoughts on to my TVR guy. He replaced the top diff bush recently, and there are no other symptoms of the diff moving, but it is entirely possible. Snetterton involves 5 hard braking efforts, and of course a similar number of hard accelerations.
I cannot say that I ever glanced at the odometer while out on track. So cannot comment on that one. Five years ago I lost both the speedo and odometer when my speed sensor failed, and again when mice chewed the wires off, so clearly that controls both. I will watch next time it happens, as that will help diagnosis.
No fuses blown. I have the glow when they blow type, so just a glance at the fuse box tells me that.
My only other thought is a loose wire on a terminal in the dash. The dash top has been off in the last six months and things were moved around. As the fault happened on lifting off the throttle, it is a distinct possibility.
I am thinking and feeding.
I will pass the thoughts on to my TVR guy. He replaced the top diff bush recently, and there are no other symptoms of the diff moving, but it is entirely possible. Snetterton involves 5 hard braking efforts, and of course a similar number of hard accelerations.
I cannot say that I ever glanced at the odometer while out on track. So cannot comment on that one. Five years ago I lost both the speedo and odometer when my speed sensor failed, and again when mice chewed the wires off, so clearly that controls both. I will watch next time it happens, as that will help diagnosis.
No fuses blown. I have the glow when they blow type, so just a glance at the fuse box tells me that.
My only other thought is a loose wire on a terminal in the dash. The dash top has been off in the last six months and things were moved around. As the fault happened on lifting off the throttle, it is a distinct possibility.
tonys said:
Bit of a long-shot but could it be possible that the diff is moving slightly thus increasing the gap and thus the affecting readings?
Of course, it could move and reduce the gap, or even connect with the sensor, which wouldn't help
Hard driving on track might just generate a fraction more movement than slightly less spirited road driving.
Another thought, depending on which fuse box you have, reversing light and something else, which I forget, is supplied via same fuse (10A from memory).
I suppose it's also possible that it's the speedo playing up. It's difficult if it's intermittent, but speedometer and odometer stopping tends to point to speedo fault, speedo on it's own tends to point to sensor/transducer.
Just some food for thought.
Of course, it could move and reduce the gap, or even connect with the sensor, which wouldn't help
Hard driving on track might just generate a fraction more movement than slightly less spirited road driving.
Another thought, depending on which fuse box you have, reversing light and something else, which I forget, is supplied via same fuse (10A from memory).
I suppose it's also possible that it's the speedo playing up. It's difficult if it's intermittent, but speedometer and odometer stopping tends to point to speedo fault, speedo on it's own tends to point to sensor/transducer.
Just some food for thought.
I've just re-read what I wrote.
What I meant to say was of course, speedo and odometer stopping point to transducer fault, either speedo or odometer on their own point to the actual speedo
Basically, the opposite to my original ramblings. Must be an age thing
. Good luck sorting it.
tonys said:
tonys said:
Bit of a long-shot but could it be possible that the diff is moving slightly thus increasing the gap and thus the affecting readings?
Of course, it could move and reduce the gap, or even connect with the sensor, which wouldn't help
Hard driving on track might just generate a fraction more movement than slightly less spirited road driving.
Another thought, depending on which fuse box you have, reversing light and something else, which I forget, is supplied via same fuse (10A from memory).
I suppose it's also possible that it's the speedo playing up. It's difficult if it's intermittent, but speedometer and odometer stopping tends to point to speedo fault, speedo on it's own tends to point to sensor/transducer.
Just some food for thought.
Of course, it could move and reduce the gap, or even connect with the sensor, which wouldn't help
Hard driving on track might just generate a fraction more movement than slightly less spirited road driving.
Another thought, depending on which fuse box you have, reversing light and something else, which I forget, is supplied via same fuse (10A from memory).
I suppose it's also possible that it's the speedo playing up. It's difficult if it's intermittent, but speedometer and odometer stopping tends to point to speedo fault, speedo on it's own tends to point to sensor/transducer.
Just some food for thought.
I've just re-read what I wrote.
What I meant to say was of course, speedo and odometer stopping point to transducer fault, either speedo or odometer on their own point to the actual speedo
Basically, the opposite to my original ramblings. Must be an age thing
. Good luck sorting it.
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