REV counter gremlin

[johns3c]

Following a cleanout of carbon deposits inside the throttle assembly on my S3C I'd rather expected a sensationally smooth 1000 RPM idle afterwards... What I got was a 1700 RPM idle and a REV counter which just sits below 1500 rpm with the ignition switched off ! By adjusting the screw on the plenum chamber it was possible to reset the idle to 1000 RPM - but how to cure the new REV counter problem ? From previous discussions it seems 'they all do that sir' is one approach. But surely there must be a logical reason to this. Anybody got ideas/experience here ?
Cheers, John

[GreenV8S]

quote:Following a cleanout of carbon deposits inside the throttle assembly on my S3C I'd rather expected a sensationally smooth 1000 RPM idle afterwards... What I got was a 1700 RPM idle and a REV counter which just sits below 1500 rpm with the ignition switched off ! By adjusting the screw on the plenum chamber it was possible to reset the idle to 1000 RPM - but how to cure the new REV counter problem ? From previous discussions it seems 'they all do that sir' is one approach. But surely there must be a logical reason to this. Anybody got ideas/experience here ?
Cheers, John

If your rev counter is like mine, the rev counter is driven by a stepper motor, and simply freezes when you turn the ignition off. If you blip the throttle before you switch off, you can get it to show any revs you like. If the idle speed is right (1000 ish) it should show this when you switch off from idle.

Cheers,
Peter Humphries (and a green V8S)

[CarZee]

hmm.. no stepper motor in the wiring diagram for my 1.5.. or is it internal to the Tacho housing?

either way, my rev counter doesn't work at all..

the wire from the coil disappears toward the bulkhead where I expect it goes thru to the cold start resistor (mounted on the bulkhead or under the dash?) then branches off to the tacho.

Is there a common cause of the rev-counter failing? eg failed connection on back of dashboard or on the back of the resistor.

Ignition itself is all okay so I guess the resistor and wiring thereto is all intact.

Any tips...

(sorry - I hijacked another thread.. so many questions... I should just compile a list and post it out with a fiver attached.. )

[John Mac]

If the S1.5 is the same as my S2 then the Tach.is electro/mechanical.Mine has packed up and is stuck on 2000rpm. Iv'e had it checked and I'm told that I have all three pulses going to the instrument therefore its the instrument thats knackered.Have you checked yours? I've tried to contact Speedy Cables for a replacement but they are according to others pretty slow to respond to anything. I've tried Penninsular Motors and they don't even respond to requests. If you get better luck please let me know. Out of interest is your trip recorder still working on the speedo, both the Tach and the trip failed at the same time which seems coincidental.

[CarZee]

quote:Out of interest is your trip recorder still working on the speedo, both the Tach and the trip failed at the same time which seems coincidental.

hmm.. well I have a seperate problem with the speedo being moody, so I ascrived the the dicky odometer to that.

I'll have another look, because it should have moved some as the speedo has been working 75%, 75% of the time..

I have to say, my feeling is that it must be coincidence or a bad earth, because the odometer count is derived from the number of pulses received by the speedometer.

Is there someone who could recondition the tacho if that is the failing part?

[HarryW]

CZ, are you sure Matt didn't sell you a pup as all I've seen from your post's so far has been for the gremlins

I would like to be able to help you on this one but I think Alicia Silverstone(sp?) made a film detailing my knowledge of the S2's electrics

I have a speedo that works 99% of the time if thats any comfort, you have to learn the gear/rpm/speed 'graph' off by heart,.. whoops your rev counters playing up as well, so thats a non-starter.

You'll just have to learn the gear/engine note/speed 'graph' then

Welcome to S's

Harry

[CarZee]

I hope I'm not giving the impression that the car is full of problems.. it's not.. just a few quirks which are to be expected of a car this age that isn't run every day..

I am pleased with the car.. it's great fun to drive and own.. I just want to 'make it my own' so to speak, and fixing these niggles is part of that..

After all, I'll need the speedo for the MOT (not 'til April) and I'd quite like the Rev counter for my next track day..

[tonystiny]

F.Y.I.
Your speedo does not necessarily have to work for the MOT test.
Unless they take it for a test drive the MOT tester has no way of knowing whether it works or not.
The only reason for them to take it for a test drive is if electronic brake tester is not working. They would then have to resort to using a tappling meter, a device which is normally used for testing certain 4x4 vehicles.
I am not suggesting you should use the car with a faulty speedo, that would be illegal.

Tony