Need help car losing power

[zaxxe30]

Hi I recently bought a 1987 325i cabrio. I am having some issues. first off the tach doesn't work and the speedo doesn't either unless I'm over 20 mph and I don't think its accurate. The other problem Is sometimes my car would lose power while its started then get it right back in less than 1 second the car stays started but you just hear the engine kind of stop then wake right back up and the light would turn off then come right back on. I've checked all fuses nothing seems to be wrong, also my antenna doesn't go up I have to pull it out by hand. Please help ASAP. thank you

[dewme5]

Just bought it? There's a chance the computer has been reset. If that's the case, it just needs driving to bring it back to good form. 75 miles or so, of spirited driving, and it'll run as good as it's going to.

You can try lubing up the antenna a little bit. Just some corrosion in there is my assumption.

Tach. Probably comes alive after bumping around a little. There is a battery replacement tutorial somewhere for that.

[zaxxe30]

After driving it's a little better probably just from sitting a long time. The tach doesn't work still and the lights don't turn on for just the tach. Also my obc doesn't turn on at all and I think my Speedo is off sometimes

[Bullhead]

After driving it's a little better probably just from sitting a long time. The tach doesn't work still and the lights don't turn on for just the tach. Also my obc doesn't turn on at all and I think my Speedo is off sometimes

From my research (I have the same issue) your SI board batteries are dead. If the car sits with a dead battery or no battery for longer than a couple weeks the little aa NiCad batteries die and they are what powers the tach, mpg meter and temp gauge. You have to get some new batteries then take the dash pod out, get to the actual board then some soldering goodness is needed. I am no expert at this but there is a good post here somewhere showing how to do it.

[Bullhead]

P.S. look for it in the electronics section.

[zaxxe30]

Ooooo ok the car was sitting with a full dead battery for a long time before I bought it (auction) and when I got a new battery the temp gas and Speedo all work you said the si batteries but the service indicator led's work

[Andy.B]

It sounds like you might have some loose ground wires. Check the battery cables and the engine grounds. I'd also check the relays. A bad si board battery wouldn't make the engine cut in and out.