Stevo Posted October 29, 2007 Share Posted October 29, 2007 Ok - I don't know enough detail about the ins and outs of the actual fault to post it all here but the gist of it is as follows.... Bought myself what I thought was a tidy NA but soon noticed that the speed indicated on the dial didn't seem to match the actual speed I thought I was doing. (The speedo dial reads in MPH). So, in it went to Envy expecting to have to replace the speed convertor and that would be it. Well, coming up to 4 weeks now and the car is still with Envy. It took several different convertors before the Envy lads were able to get it to read in mph but even when they did, there appears to be something amiss and the speedo is still over-reading/isn't accurate. Only Gaz could adequately go through what they have or haven't tried but my last communications with Gaz today are basically that they are running out of options and are a bit stumped. Obviously, all I want is to be able to know what speed I'm doing in mph (don't want to go down the route of a separate sat nav or anything like that) without having to drive along doing mental arithmetic all the time. Can anyone recommend an auto-electrician that might be able to take a closer look at the car please? (ideally in North East) Cheers Link to comment Share on other sites More sharing options...
JustGav Posted October 29, 2007 Share Posted October 29, 2007 How far out is it... Bear in mind most speedos are out to some degree. The circuit for the speed system should be as follows.. speed sensor -> speedo -> odo -> ecu (I believe, will dig out the diagram in a mo to confirm). Link to comment Share on other sites More sharing options...
Stevo Posted October 29, 2007 Author Share Posted October 29, 2007 Gaz tells me when they tested it, they were doing a confirmed 50mph (GPS) but the speedo reckoned only 20mph. From the investigation they have done so far, it would appear that some other electrical device that no longer on the car has buggered up the wiring circuits Link to comment Share on other sites More sharing options...
JustGav Posted October 29, 2007 Share Posted October 29, 2007 If you remove the speed convertor does the dash read correctly in kmh, ie 120kmh for 70mph (roughly)? Link to comment Share on other sites More sharing options...
Stevo Posted October 29, 2007 Author Share Posted October 29, 2007 That is exactly what Envy are going to check tomorrow mate. Stupid question time (I think!) - If the dash is accurately reading in Kmh, would fitting one of the dials in the attached pics give me what I'm after? I.e. the sensor would still be in kmh but I'd be able to see the mph equivalent? Link to comment Share on other sites More sharing options...
Stevo Posted October 29, 2007 Author Share Posted October 29, 2007 Any more thoughts? Link to comment Share on other sites More sharing options...
JustGav Posted October 29, 2007 Share Posted October 29, 2007 Not 100% on the gauges, I would however see how it goes with the KPH bit.. I had a dodgy convertor on the NA shed, and to be fair I just ripped it out because it kept causing issues. I've now gotten used to the kph bit.. Link to comment Share on other sites More sharing options...
Stevo Posted October 29, 2007 Author Share Posted October 29, 2007 So you just use the car reading in kph? Not sure I could get used to that given that its my daily driver and the mrs will be using it as well (I think 3 points would be a certainty there!) After 3 and a bit weeks without the car (have only owned it for 5) this is driving me to despair! Link to comment Share on other sites More sharing options...
JustGav Posted October 29, 2007 Share Posted October 29, 2007 To be fair, if I go out for a drive I usually have the road angel in the car anyway, and it does double up as my checking system. Mind you I grew up on Metric system anyway, so it is an easy transition for me. Link to comment Share on other sites More sharing options...
Stevo Posted October 29, 2007 Author Share Posted October 29, 2007 Somebody suggested to me that Peter Betts at Thor Racing might be able to sort me out - anyone know the fella? Link to comment Share on other sites More sharing options...
JustGav Posted October 29, 2007 Share Posted October 29, 2007 Somebody suggested to me that Peter Betts at Thor Racing might be able to sort me out - anyone know the fella? The Thor speed convertor is one of the best ones going to be honest by all accounts. Link to comment Share on other sites More sharing options...
mattysupra Posted October 30, 2007 Share Posted October 30, 2007 4 weeks? i think i would of done something that would get me locked up for another night. I have never had any dealings with envy before but for them to take that long sorting a speedo i must guess that you have something major wrong? Anyway the speedo face's look simular to mine apart from they look like they will leave your speedo reading a little fast ( stop you getting a speeding ticket) the 200mph bit looks like it is in the place where the 180 should go. All we did on mine was fit a speedo face with 200mph on it and then stick on rolling road with correct reading of speed and then fit the correct resistor to make it read correct. But i am going back about 8 years when there was no one about offering the correct face and stuff. Link to comment Share on other sites More sharing options...
Digsy Posted October 30, 2007 Share Posted October 30, 2007 Gaz tells me when they tested it, they were doing a confirmed 50mph (GPS) but the speedo reckoned only 20mph. A speedo converter multiplies the input speed by 5/8 to convert it from kph to mph. 50mph x 5/8 x 5/8 = 19.53mph Sounds like you have two speed converters. Link to comment Share on other sites More sharing options...
Stevo Posted October 30, 2007 Author Share Posted October 30, 2007 It has been difficult to stay patient but I guess with this kind of problem, they're difficult to trace and its just down to trial and error. So you fitted the new speedo face onto yours etc with using a speed convertor too? Link to comment Share on other sites More sharing options...
Stevo Posted October 30, 2007 Author Share Posted October 30, 2007 Digsy, cheers - that explains why Envy thought that then. No 2nd device was visible so they have been trying to have a look around in case there was one hard-wired direct to the gear box or something. Haven't found anything though... Link to comment Share on other sites More sharing options...
mattysupra Posted October 30, 2007 Share Posted October 30, 2007 It has been difficult to stay patient but I guess with this kind of problem, they're difficult to trace and its just down to trial and error. So you fitted the new speedo face onto yours etc with using a speed convertor too? I didn't fit a so called speed converter that you buy now a days, They convert the kmh to read in mph but you only end up using half the dial. When we changed the face on mine the speedo was not accurate so i had it calibrated. The dial i fitted was about 20% out to the old face. (200mph where 180mph should be etc) so to make it read write a resister was fitted. Link to comment Share on other sites More sharing options...
JustGav Posted October 30, 2007 Share Posted October 30, 2007 I didn't fit a so called speed converter that you buy now a days, They convert the kmh to read in mph but you only end up using half the dial. When we changed the face on mine the speedo was not accurate so i had it calibrated. The dial i fitted was about 20% out to the old face. (200mph where 180mph should be etc) so to make it read write a resister was fitted. The supra system isn't voltage based as far as I know, it is pulse derived, so not 100% sure how a resistor would help with regards that. Link to comment Share on other sites More sharing options...
mattysupra Posted October 30, 2007 Share Posted October 30, 2007 The supra system isn't voltage based as far as I know, it is pulse derived, so not 100% sure how a resistor would help with regards that. I may be wrong about the resistor but that is how i understood they had done it. How do the speedo converters work that go in the loom between the gearbox and speedo? I thought they was a resistor to that made the signal 5/8 less or something like that? Link to comment Share on other sites More sharing options...
JustGav Posted October 30, 2007 Share Posted October 30, 2007 There are various forms of speed sensors.. 1. Direct drive... These are cable driven units, which consist of a set of gears within the unit which do the conversion 2. Electronic Voltage... These provide a voltage dependant on the speed of the sensor, in this case a resistor although crude would do it 3. Pulse driven... These provide pulses in order to deliver the speed info, in order to convert between them, some electronics is required to buffer/recalc and deliver the signal. I'm almost 100% sure that the supra is the third type. Link to comment Share on other sites More sharing options...
Stevo Posted October 30, 2007 Author Share Posted October 30, 2007 Just to update you all. Now have the car back (picked her up tonight) but the problem isn't sorted. Basically on a test run today, with the convertor out, Envy discovered a strange lack of consistency.... Using a GPS to verify actual speed, at 25mph the car indicated 30 (so over-read) but at 75mph the car indicated 60 (so under-read). Totally stumped for solutions now so thought may as well get the car back and fit a Road Angel or something to give me my speed details. Not really the outcome I wanted but guess it'll suffice for the time being. Oh, and by the way, a big thanks to Gaz Walker for the significant reduction in cost compared to the real amount of labour hours. Link to comment Share on other sites More sharing options...
Chris Wilson Posted October 30, 2007 Share Posted October 30, 2007 Have you tried another speedo head? Link to comment Share on other sites More sharing options...
JustGav Posted October 30, 2007 Share Posted October 30, 2007 Have you tried another speedo head? Seems a damn good idea actually... That would then eliminate a lot of questions actually... Link to comment Share on other sites More sharing options...
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