Revotec Speedometer Calibration And Temp Gauge Problem

[kevin the chicken]

Two problems with which I need help

 

1) As soon as I start the engine of my S7 redtop the temperature gauge starts to creep up and before I have even moved it out of the garage the needle is on the stop. It has a full set of revotec instruments which are newly installed as the speedo only has 900 odd miles on it. If you pull the wire off the sender it goes back down to zero in about 5 seconds. The sender is a brand new one and is the correct one for the gauge. I would have thought if it was an earth fault it would have shot up as quick as it goes down when you pull the wire off. Also I don't remeber it doing this the first time I got it running a couple of months ago. Could it be something we did when we were trying to sort the wiring out?

 

2) I took the car out just for a quick run of a couple of miles to show my daughter and took a look at the speedo when I was doing around 3500-4000 in 5th gear and was surprised to see that it was showing less than 40mph. I know your backside is on the ground and this can give a greater sense of speed but I would have said that I was doing at least 50mph and more likely 60mph judging from the wind buffeting me! If anyone has a set of calibration instructions for this speedo that they could pass my way in some form or other then I would be extremely grateful. I know that I could run down the road with my wife following in her tin top but would like to check it out in my garage this week while she is at work.

 

Regards

Kevin

[Bob Tucker]

Got a satnav?

Mine has a very accurate speedo which I used to check my Rally design speedo.

Most likely cause is a lost magnet or the sensor is not close enough to the magnets or bolts, whichever you have triggering the sensor.

 

I have a 3.92 diff, 185/60/14 tyres & in 5th 1000 revs = exactly 20 mph.

So ata guess you are only getting 3 pulses per propshaft rev instead of 4, ie actual 52 mph at indicated 40mph

40/3*4

 

 

BTW my OMD (Revotec lookalikes) water temp & oil temp are also wrong, they both read very low. Rally design couldnt help, so Ive just got used to where "normal" is & look for any difference.

 

Calibration instructions for my OMD guages are here..

http://www.caigauge.com/page21.html

 

HTH Bob

[kevin the chicken]

_{My wife has just downloaded a speedometer app to her smart phone as that has GPS so I will give that a go when I get chance. I am running the same size tyres as you but the diff is an unknown. I'll have a look underneath and see how it is triggered first though. Thanks for that, I should be able to work something out one way or another. No doubt I shall uncover a couple more bodges.}

 

_Regards

_Kevin

[Bob Tucker]

BTW my sensor has an LED light which flashes whenever it is triggered.

Jack up the car, turn on ignition, & spin the propshaft to check it.