Flickering,wavering speedo needle and strange events!

[leslloyd]

I've just returned to Mackay from a trip down to Noosa in the VL,now on the way down over a period of 100km's i noticed the speedo doing the above,the strange thing is while doing this the motor started running real rough and was generally missing and surging.Foot flat to the floor seemed to clear it temporarily.
I suspected the cable was ready to break but the rough running motor?at the same time??.
Anyway the problem,or both righted themselves, thereafter the trip was then uneventful.
Anybody heard of this before in a VL?Did a search but could find nothing.
colin

 

[detox_nath83]

Hey man well a flickering needle jumpy, etc is basically a worn nylon gear in the rear of the cluster for speedo drive cable. which is common on a 22 year old dash cluster..
As for the rough,surging,missing could be a number of things. i would think both things happening together would be coincidence.

a Miss could simply be a bad lead or plug, running rough could be Vacuum leaks, Blocked Filters, AFM starting to fail, or air leaks in intake piping after AFM B4 Throttle Body.
Dissy contacts are worn/pitted, Dirty Throttle body, AAC (Auxilery Air Control) valve blocked(Mainly Idle)

Bad connections on electrical plugs and so on. I would suggest go over all electrical plugs with some sort of penetrine Ie: (INOX, WD40, RP7) then start with the least expensive parts first. (Plugs, Leads, Fuel Filter, Air Filter.
Quite an easy engine to work over and fault find man goodluck.

 

[leslloyd]

Don't you think it strange that if the speedo is worn then why did it immediately come good,at the same time as the engine
started running fine again.
As to these other issues,plug leads etc they have all been replaced over the years,the engine is running top notch now.
Still i'll go over it with some WD40,it never hurts.
So nobody can think of anything?
What is it that registers the car is moving?
cheers
colin

 

[Tree cutter]

Try a new speedo cable. I had the same problem with my VL years ago. It would surge really bad when the speedo needle flickered. The needle only flickered when travelling below 80Kph. I replaced the speedo cable and never had a problem again. When the cable wears and starts to jam it upsets the speed sensor in the back of the instrument cluster because it thinks you are travelling at 10 Kph then instantly jump to 80Kph then back to 10Kph over and over again.

 

[electro cruiser]

but how does the speedo affect the engine? the cable from the gearbox to the speedo shouldnt affect the engine like that. thats my thoughts anyways, i could be wrong

 

[TMM]

but how does the speedo affect the engine? the cable from the gearbox to the speedo shouldnt affect the engine like that. thats my thoughts anyways, i could be wrong

It doesn't, probably just a coincidence.

 

[leslloyd]

It doesn't, probably just a coincidence

Probably,i as thinking there could be some connection between the speed sensor and the computer,and the flickering as upsetting or sending incorrect impulses to it,hence the missing.

 

[de_overfiend]

your speed sensor is dying. the speed sensor talks to the gearbox comp and ecu, and is an intragal part of the system. Only happens with VL s as they are technically a nissan engine. If it fails you get no speedo and the gearbox (in a auto) goes into limp mode. the ecu also goes into limp mode. you can get another one from a wrecker for 20-60 bucks depending on the wrecker. new one is around $120.