Weird Issue - Maybe One For Brian

[Stefan on probation]

88 E30 Chromie Convertible, kept in a garage and fired up and driven every so often but last week tried to fire it up and got a "click" uh oh I know this sound drained battery.

In the past I had an issue with the battery draining within a week if the car wasn't used so last year I went through the car and removed the alarm completely tracing all the wires cutting them out and soldering any cut wires together and protecting them with heat shrink and all was well un tie this hiccup.

Tried the car a second time and it fire up fine but the stereo had lost all its settings so to me it seems that there was a break between the battery and everything else, checked battery connections all seemed fine then left the car.

Next day fired up the car went of a drive stopped to pick some stuff u then fired it up again,whilst pulling away the ABS and Engine Management light where flashing and it seemed like the car was stuttering/choking after some heavy acceleration it cleared up and has been fine since.

The one thing that is weird is that for ages I have had an issue with the Temp, Accelerator and Fuel Guestimator needles having a life of their own but now they seem back to normal, the clocks have been out cleaned, checked any dodgy soldering redone etc etc but I can't explain this one.

Damp maybe or some other Gremlin?

[Speedtouch]

If the battery has gone flat (i.e., fallen below the threshold voltage required to operate the electronics properly), any computerised stuff (ECU, etc.) will often need to relearn its settings.

So, once you have it up and running again, the battery will eventually recharge enough to power the electronics correctly - nothing to worry about, although you should really try and avoid it (mainly because of the nuisance it causes), by using a trickle/solar charger or similar if leaving the car for extended periods.

[Stefan on probation]

It was a unexplained glitch as I tried it again 5 seconds later and it fired up as normal with no issues as you normally have with a low charged battery and it has all been fine since the alarm was removed last year but there must be some reasoning to it, the car is started weekly and I have no power to the garage as its off site.

Reminds me that I need to carry my capacitance booster pack with me now just in case.

[Speedtouch]

Possible loose or corroded battery terminals or engine-to-body earth strap.

I would look at every earth connection (brown wires on BMWs) and check for corrosion or loose bolts holding them to the body.

[Brianmoooore]

It'll be a poor connection on the battery connections - either at the battery or at the other end of the thick wires.
After starting it, feel all the connections by hand. The faulty one will likely be warm or even hot.

[Stefan on probation]

Battery connections are fine as they have been checked, will check the main engine to body strap as I don't think I have checked that one but the earth connection under the glove box was all okay when I removed the alarm and tightened it all up again last year.

[Brianmoooore]

Check it anyway, but a fault here wouldn't affect the radio memory.
Check the red wires attached to the battery + terminal, and also that a hex. cap bolt, visible in the deck of the fusebox is tight. This bolt attaches the red wire from the battery to the fusebox circuit board, and also attaches the red wire that goes on to the ignition switch. It doesn't normally work loose on its own, but is vulnerable to meddlers with an allen key at some time in the car's life.

[Stefan on probation]

Will do Brian, the erasing of the radio memory took me back to the days of a dead battery syndrome.

[Brianmoooore]

Cap bolt has a loose nut on the bottom end of it, so only check that it's tight, not back off and re tighten. If it is loose, you'll have to split the fusebox and get a spanner on the nut.

[HartgeH27]

SexyLady (Diable) play fair and you can stay.

[Nobby_N]

Lotus lover