Jumpy rev counter..

[tejr]

My rev counter has a bit of a swing going on as I accelerate so its kinda guess work when to change gear as I approach 7krpm as it seems to read +/-1000rpm!!!

Is this common? Easy fix? New tach?

While we are talking gauges, I hear some people sacrifice the clock for a oil temp gauge - where can I source one that looks similar to the standard dials?

[Tanguero]

The classic reason for the rev counter being erratic is a problem with the big fuse. I haven't experienced it myself - but the fuse is easy enough to change. Its just behind the coil packs at the back of the engine on top.

[tejr]

Am I right in thinking its similar to an ANL fuse? I might have some spares lying around, some use more than 100A to replace them with right? will a 150-200 be too much?

Although I have to say, its not erratic/hit&miss/fails to work at times.. it just seems underdamped ?

Edited by tejr on Thursday 23 September 11:18

[Tanguero]

The fuse is of questionable use at best - it is in the direct connection between alternator and battery. I believe some people have simply eliminated it all together so I wouldn't think that a higher value would be a problem. I have never heard of one actually blowing...

If your rev counter isn't erratic then this may well be a complete red herring anyway! The usual report is of the counter spiking and being intermittent if its fuse related.

If its a fault with the instrument its self Speedy Cables can restore them - though reputedly they are "speedy" in name only.

Edited by Tanguero on Thursday 23 September 11:38

[Gazzab]

It is the big fuse. I would recommend that you order a few proper ones or go for the Steve Heath version. Plus it might be worth getting a new fuse holder at the same time as you may find it cracked etc.
Overall I would not recommend increasing the fuse ampage. What would the insurer say if your car went up in smoke.

[Tanguero]

Gazzab said:

Overall I would not recommend increasing the fuse ampage. What would the insurer say if your car went up in smoke.

Good point!

[itiejim]

Big fuse always gets raised here, quite rightly. However, as an electrical fault this tends to show as the rev counter spiking, or losing signal. It is also possible that the rev counter needle loses it's damped effect and waves all over the place as the revs change quickly. This can only be cured by getting Speedy Cables to repair it.

[Gray_101]

my rev counter bounces around ever time i change gear, but its fine under constant acceleration.

i changed my big fuse and it made no differance, but i fitted a 100 amp fuse and not the bigger steve heath one.

Does the higher amp fuse make a differance ?

i dont know, but ive just learnt to live with it and change gear on the shift light while the ajp is screaming its head off

[itiejim]

Sounds like the rev counter to me. A higher rated fuse won't make any difference.

[Gazzab]

Isnt Steve Heaths the same ampage just a physically bigger thing thats less prone to cracking etc?

[FUBAR]

Gray_101 said:

my rev counter bounces around ever time i change gear, but its fine under constant acceleration.

i changed my big fuse and it made no differance, but i fitted a 100 amp fuse and not the bigger steve heath one.

Does the higher amp fuse make a differance ?

i dont know, but ive just learnt to live with it and change gear on the shift light while the ajp is screaming its head off

Same as you. Always been the same. Removing the big fuse has made no difference what so ever. I just live with it

[tejr]

Nice to know I'm not the only one! It doesn't bother me hugely to be honest, just looks like its broken (ie. a TVR thing!)

[Gray_101]

Gazzab said:

Isnt Steve Heaths the same ampage just a physically bigger thing thats less prone to cracking etc?

I thought the Steve Heath fuse is 125 amp,( but i may be wrong ) and ive heard its a marked improvement on the 100 amp fuse

[Gazzab]

https://delta.securesslhost.net/~shenglt/catalog/i...

It's 100 amp and for a few quid more you can get a new holder.

[Jimii]

My rev counter is also a bit wobbley ,I fitted a new holder and fuse it made no difference

[RichV6]

Mine started doing the same over the summer and changing the fuse made no difference. Question is, is it just the needle going haywire or the whole tacho? Does the shift light / buzzer still go at the correct engine speed?

[mikethebike1127]

I ditched the big fuse and it was the best move I ever made......rev counter now working perfectly, battery charging better & the car seems to run smoother. As for the dangers of removing it....b*ll*cks....the fire hazard thing is scare mungering....if the alternator did by chance start to over charge the battery, the only harm would be a boiled battery....it's not going to heat up that size of cable sufficienty to cause a fire.

[knight]

My rev counter sometimes refuses to work for 10-15 mins then just springs into life! I have had the fuse removed so that's not the problem and last year, or earlier this year, I had the rev counter at speedy cables and they found no fault!

[Jimii]

I also tried it without fuse and it was still the same, shift light seems to work fine and its also fine while accelerating, mine wobbles on the gear change or if your in neutral and you give it a nice rev, seems to me it just doesn't like making very quick movements

[mikeinsheffield]

For the sake of the small cost to replace the "big fuse" - just do it at every service and treat it as a "consumable". I experienced the "erratic rec vounter" shortly before I was totally stranded at the junction of the A1 and North Circular at rush hour. Not fun. Neither was the AA journey all the way back to Sheffield.....