Odd problem....

[sam gamgee]

....to me, that is!
Been having slightly erratic tickover problems along with speedo dancing around merrily, especially when fans cut in.
Weather crap up here of late (when I`ve been here!) so not ran Griff (500) for couple of weeks, thought I`d better at least run up to operating temp in garage and move wheels etc.
Left car to warm up, goes back to switch off, fans were running at half (got 2 speed thingy from mr Beer! Tis excellent, btw.) Anyway, speedo dancing as ever and tickover slightly too high at around 1200 rpm. as soon as I open door, revs drop to normal and speedo stops dancing at least for a while!!!
So, I think it`s something to do with earthing, can anyone confirm this or offer any advice? Been meaning to look at this for some time now, just want to drive the thing, really, when the time allows...sorry to prattle on everyone.

Dave.

Oh, tis a pre-serp/T5 box, 1994...

Edited by sam gamgee on Sunday 10th December 00:47

Edited by sam gamgee on Sunday 10th December 09:22

[steve-v8s]

Sounds like a high impendence earth connection to me. I would suggest you track down the various grounding points and check that they are tight and clean.

[sam gamgee]

Hi, steve, have cleaned the accessable ones at front (near radiator) and chassis to engine (behind o/s fr wheel). Havent yet properly checked out those under console, looks right p.i.a. of job.....anywhere else that may be responsible directly anyone? Part of problem also is that p**ing down here and my garage has very little space to work in...kinda puts one off some jobs! But do wanna sort it . Thanks.

Dave.

[steve-v8s]

More knowledgeable people will be along soon, but have you checked all the –ve leads going to the battery ? my car has one thick one and several thinner ones. Had odd problems once when the fixing for the thinner ones became loose.

How about attaching one end of a length of cable to a good ground and going round bits that should be earthed and seeing in the fault goes away. That may give a clue where the problem is.

[davetherave1970]

I read somewhere on here that having the speedo "bounce" when at a stand still could be the rev counter wire running close to the speedo wire behind the dash and interfering.
Mine done this "bounce" and when I blip the throttle the speedo settles for a second or so!
I'm gonna try taking the dash out and re-routing the cables!

[sam gamgee]

davetherave1970 said:

I read somewhere on here that having the speedo "bounce" when at a stand still could be the rev counter wire running close to the speedo wire behind the dash and interfering.
Mine done this "bounce" and when I blip the throttle the speedo settles for a second or so!
I'm gonna try taking the dash out and re-routing the cables!

Hi, might take this route sometime next year as thinking of changing dash when time allows....let us know how you get on if you remember. In the meantime I think I need to concentrate on the above ie. earthing/batt wires etc. Thanks Dave the rave! Do believe problem is earthing due also to the fact that the other instrument readings are, shall we say, not stable. Was told by a dealer and well respected indy that this is normal/can/has been sorted by replacing leads with standard etc. All bo**ocks, I now think!

Dave.

Edited by sam gamgee on Sunday 10th December 14:12

[Cider Andy]

It does sound like a faulty (or 'high impedance', as someone correctly posted) ground connection that's being made properly via the switch in the sill when the door's open. Does the car turn over properly on the starter? I'd suggest the grounding point on to the top of the engine at the nearside, somewhere behind the plenum chamber. If it cranks slowly it is more likely the grounding cable between the engine and chassis, but I think you've checked that already.

[sam gamgee]

Cider Andy said:

It does sound like a faulty (or 'high impedance', as someone correctly posted) ground connection that's being made properly via the switch in the sill when the door's open. Does the car turn over properly on the starter? I'd suggest the grounding point on to the top of the engine at the nearside, somewhere behind the plenum chamber. If it cranks slowly it is more likely the grounding cable between the engine and chassis, but I think you've checked that already.

Hi Andy, thanks for the reply.
No, not checked that one out, yet! and, yes, it seems to crank fine....will check this out tomorrow eve if I get time, hope its this.
Thanks as usual for the replies etc.

Dave.

[sam gamgee]

Blimey, Andy, that there earth at back of plenum is a bu**er to get at! Will have another go at weekend when not so rushed/tired.

Dave.