tacho's no joke
Discussion
OK the cerbie has just come back from the workshop, a few niggles after 1st week of ownership...main problem a tacho which has a mind of its own. Bounces between 2K and 4.5K on gearchange. Don't trust tach at all, driving by ear now because on acceleration it seems to give a max reading of 5 - 5.5K but I'm sure it's more (engine revs still climbing...ear!!). Also havn't seen the idiot light yet!!!! Told by the dealer that the bouncing is normal. Is this true or classic fob off???
Car has a TVR sprint warranty so theoretically could get the tach replaced.
Over to you guys with much more experience than me.
Car has a TVR sprint warranty so theoretically could get the tach replaced.
Over to you guys with much more experience than me.
I have a similar problem - completely looses the plot when it gets to 6,000 rpm and just waves between 6 & 7, change up light has never come on either although I think I've hit the rev limiter a few times.
Shouldn't do it but my dealer has failed to track it down, mainly because 6,000 rpm in any gear other than first is a bit quick on the road
and you don't want to be doing it on an unloaded engine 
I've not bothered with this too much as it's right at the top of the rev range, imagine it'll be f
g annoying where it's occurring on yours 
Shouldn't do it but my dealer has failed to track it down, mainly because 6,000 rpm in any gear other than first is a bit quick on the road
and you don't want to be doing it on an unloaded engine I've not bothered with this too much as it's right at the top of the rev range, imagine it'll be f
g annoying where it's occurring on yours tacho's do this when the jobie on the alternator is going they get to hot and slowley break down ive had two go on mine both started with same problem when your belt snapps they go hay wire as well or the little plug on alternator can work loose giving bad reading take it off crimp it wd4o usally sorts it out
pain on 4.5 air pipes off need little hand
pain on 4.5 air pipes off need little hand
Only time I have seen this was when the charging fuse went. OK to 5000rpm then all over the place. I thought Rev Counter was duff but a change of fuse sorted it out.
Thing is with rev counters, all they do is count pulses and convert them to signals so that the gizmo behind the needle knows where to point. If the dial moves then the mechanism is working and the fault most likely resides elsewhere.
Leaping about during gear changes and at high revs is a symptom of an electrical problem, the energy required to run the engine (fuel injectors, coils pack etc) changes under these conditions. This can effect the signal pulses to the tacho and hence it goes beserk.
Hope this helps.
Mike
Thing is with rev counters, all they do is count pulses and convert them to signals so that the gizmo behind the needle knows where to point. If the dial moves then the mechanism is working and the fault most likely resides elsewhere.
Leaping about during gear changes and at high revs is a symptom of an electrical problem, the energy required to run the engine (fuel injectors, coils pack etc) changes under these conditions. This can effect the signal pulses to the tacho and hence it goes beserk.
Hope this helps.
Mike
Thanks to all for replies,
I've looked at the threads on the charging fuse and the symptoms do appear similar, however I've had the car for about 10 days, done approx 500 miles, some at night and the battery still seems charged OK. I would have thought that there would be other problems by now. When the car went back to have various little problems sorted it also had a slight mis-fire which was diagnosed as a faulty HT lead and a new set of plugs fitted as well. All of the niggles were cured except the tach which is as bad as when the car left for the workshop. Let me try to explain exactly what it does... blip the throttle tach hits 6 to 6.5K fall s back then bounces for probably three seconds between 4.5K and 1.5K ,gradually falling to idle r.p.m. Hold engine revs and the tach doesn't want to climb much above 5.5K, again as revs fall tach bounces as previously. Main concern now is the rev limiter. Does anybody know how the rev limiter system works on Cerbies?
I've looked at the threads on the charging fuse and the symptoms do appear similar, however I've had the car for about 10 days, done approx 500 miles, some at night and the battery still seems charged OK. I would have thought that there would be other problems by now. When the car went back to have various little problems sorted it also had a slight mis-fire which was diagnosed as a faulty HT lead and a new set of plugs fitted as well. All of the niggles were cured except the tach which is as bad as when the car left for the workshop. Let me try to explain exactly what it does... blip the throttle tach hits 6 to 6.5K fall s back then bounces for probably three seconds between 4.5K and 1.5K ,gradually falling to idle r.p.m. Hold engine revs and the tach doesn't want to climb much above 5.5K, again as revs fall tach bounces as previously. Main concern now is the rev limiter. Does anybody know how the rev limiter system works on Cerbies?
Joolz says there will be nothing wrong with the charging system if you've done that many miles with no discharge problems. It will be an internal lack of damping on the needle as previously explained... you will need to either get the tacho repaired at somewhere like Speedy Cables or fit a new one from the factory. There is no rev limiter on the Cerbera as far as I'm aware since every ECU I've downloaded data from (lots!) has the rev limit set at something like 46,000rpm, and I've never felt a rev limiter come on on the road. The tacho will not be affecting the performance of your car so it is an inconvenience rather than a serious fault.
Don't worry, enjoy your car.
Don't worry, enjoy your car.
Had identical symptoms with my tacho twice. In both cases tacho was changed as being faulty (under warranty fortunately). Apparently not unusual for these tach's to act up in this way - but dont take the dealer b******s about it's normal. Thats a bit like "the sleeves will ride up with wear" ..... ohhhhhhh, suit you SIR!!!!!
Regards
John
Regards
John
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