Rev counter on blink?

[Munter]

Driving down the M54 in the torrential rain yesterday I noticed the rev counter was seemingly unconnected to the engine speed. It was happily jumping up and down 500RPM. Now I'd have said the clutch was slipping possibly, but it would drop to lower revs than related to my speed.... Plus it was moving around in jerks and not smoothly or in any relation to the throttle. Plus the clutch only has ~6000 miles on it.

Hows the Rev counter driven? If it's sticking is there a known fix? If it's tricky I might just let it die...unless I need it for the MOT?

[GreenV8S]

The tacho may be controlled by the ECU but is more likely to be connected to the coil low tension circuit. The signal here can be affected by changes on the HT side, and water spray around the HT leads could well affect it. Does the problem still occur after it's all dried out?

[Munter]

GreenV8S said:

Does the problem still occur after it's all dried out?

I'll let you know when the rain stops!
I thought I'd mention the wetness incase it was electrical driven. But with some features on the MX being older tech I thought it might be mechanically driven by a cable or the like from the gearbox.

Fingers crossed it gets better when the car dries out.

[MX-5 Lazza]

It is electronic. I believe it's driven from the ecu. I'm no help with regards a solution though...

[snotrag]

On odd occasions, mine has done this, only when the car is sat idling though. Needle sometimes jsut jumping about a bit.

Solution thus far has been - ignore it. Sorry!

[OnlyMX5ives]

On 1.8's cleaning the earth point by the front crossover pipe can solve it.

Of course now my car has started doing this the above hasn't worked !

Unfortunately mine does it so rarely its hard to track down.

[OllieWinchester]

Mine did this once, went up to about 85 on the motorway and the rev counter got stuck at 4k until i slowed to 60ish. Hasn't done it since though, and i cant remember if it was yet that day or not.