Nob behaving oddly - electrical fault?
Discussion
Can anyone help me diagnose what might be wrong here...
A couple of days after a track day last autumn my battery unexpectedly went flat (alarm triggered, etc.) so I left it charging with a battery conditioner... work and an injury got in the way and the Nob's been sat for a couple of months.
Now, the battery has taken some charge; the conditioner (a CTEK) is indicating that it's not a full charge but I can see there's a status indicator on the battery itself that is saying it's healthy.
On starting, there seems to be full power to the starter motor and the engine fires up straight away - but the revs immediately fall away and the engine stalls if I don't blip the throttle. If I keep it running a few minutes then it will (just) idle but much lower revs than usual. The cockpit lights dim as the revs fall, even though the battery seems to still have plenty of juice to restart.
I have some suspicions but car electrics are not something I know a huge amount about. So, any easy tests I can do and - failing that - any recommendations for a mobile Nob-friendly tech within reach of Sussex?
Annoyingly I can't actually drive the car right now due to a shoulder injury but obviously want to have her 100% as soon as...
...one rather optimistic (ok, clutching at straws) idea I had is that the battery discharging may have reset the ECU and all she needs is a long drive to re-learn it... any chance?
Thanks in advance, Dave
A couple of days after a track day last autumn my battery unexpectedly went flat (alarm triggered, etc.) so I left it charging with a battery conditioner... work and an injury got in the way and the Nob's been sat for a couple of months.
Now, the battery has taken some charge; the conditioner (a CTEK) is indicating that it's not a full charge but I can see there's a status indicator on the battery itself that is saying it's healthy.
On starting, there seems to be full power to the starter motor and the engine fires up straight away - but the revs immediately fall away and the engine stalls if I don't blip the throttle. If I keep it running a few minutes then it will (just) idle but much lower revs than usual. The cockpit lights dim as the revs fall, even though the battery seems to still have plenty of juice to restart.
I have some suspicions but car electrics are not something I know a huge amount about. So, any easy tests I can do and - failing that - any recommendations for a mobile Nob-friendly tech within reach of Sussex?
Annoyingly I can't actually drive the car right now due to a shoulder injury but obviously want to have her 100% as soon as...
...one rather optimistic (ok, clutching at straws) idea I had is that the battery discharging may have reset the ECU and all she needs is a long drive to re-learn it... any chance?
Thanks in advance, Dave
Sounds like a shagged battery that isn't providing enough voltage for the coils when on idle. If the CTEK isn't able to get it to full after a day or so, it's royally shagged.
I'd start with getting a new battery to ensure you aren't chasing your tail. These are the best out there.
http://tinyurl.com/49fmlzr
Of course, Halfords are very expensive - cheaper but same here
http://www.caraccessoriesandparts.co.uk/1202-bosch...
http://www.boschbatteries.co.uk/Products/BOSCH-SIL...
etc.
J
I'd start with getting a new battery to ensure you aren't chasing your tail. These are the best out there.
http://tinyurl.com/49fmlzr
Of course, Halfords are very expensive - cheaper but same here
http://www.caraccessoriesandparts.co.uk/1202-bosch...
http://www.boschbatteries.co.uk/Products/BOSCH-SIL...
etc.
J
joust said:
Sounds like a shagged battery that isn't providing enough voltage for the coils when on idle. If the CTEK isn't able to get it to full after a day or so, it's royally shagged.
I'd got to thinking that but am confused by the battery's own indicator showing that it's healthy!Ok, I'm learning stuff here though - do the coils really draw that much current? I'll go and have a read - cheers.
Indicators on the battery are not worth the indicator they are made from....
The whole electrics to run the car do take quite a load, and if it's just after you've started it then you have drained a large amount from the battery turning it over. That could explain why if you rev it for a while it gets a bit better as you'll be sticking some more charge back in. Pump, fans, ECU are all a decent load, and at idle the alternator won't be contributing much to the effect.
If the battery is shagged you also get voltage drag down due to sulphation of the plates. It can cause all sorts of funny things. The way you describe it you've probably either lost most of a cell, or you've got crud at the bottom of the cells now creating problems (leaving things uncharged for even a short time is fatal, and it's suspicious that it just "failed" and lost charge suddenly).
Given you've let the battery discharge fully, it won't last long. For the sake of £70-80 it gives you peace of mind that it isn't the battery, and if there is still a problem, it'll be much easier to find.
J
The whole electrics to run the car do take quite a load, and if it's just after you've started it then you have drained a large amount from the battery turning it over. That could explain why if you rev it for a while it gets a bit better as you'll be sticking some more charge back in. Pump, fans, ECU are all a decent load, and at idle the alternator won't be contributing much to the effect.
If the battery is shagged you also get voltage drag down due to sulphation of the plates. It can cause all sorts of funny things. The way you describe it you've probably either lost most of a cell, or you've got crud at the bottom of the cells now creating problems (leaving things uncharged for even a short time is fatal, and it's suspicious that it just "failed" and lost charge suddenly).
Given you've let the battery discharge fully, it won't last long. For the sake of £70-80 it gives you peace of mind that it isn't the battery, and if there is still a problem, it'll be much easier to find.
J
Edited by joust on Tuesday 1st March 21:49
joust said:
Sounds like a shagged battery that isn't providing enough voltage for the coils when on idle. If the CTEK isn't able to get it to full after a day or so, it's royally shagged.
I'd start with getting a new battery to ensure you aren't chasing your tail. These are the best out there.
http://tinyurl.com/49fmlzr
Of course, Halfords are very expensive - cheaper but same here
http://www.caraccessoriesandparts.co.uk/1202-bosch...
http://www.boschbatteries.co.uk/Products/BOSCH-SIL...
etc.
J
You need to get a Halfrauds trade card, batteries are then half price and most service items are reduced a fair bit.I'd start with getting a new battery to ensure you aren't chasing your tail. These are the best out there.
http://tinyurl.com/49fmlzr
Of course, Halfords are very expensive - cheaper but same here
http://www.caraccessoriesandparts.co.uk/1202-bosch...
http://www.boschbatteries.co.uk/Products/BOSCH-SIL...
etc.
J
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