Hey everyone, I’ve got a 1987 BMW 325i vert. I’ve had it for almost 8 years, I swapped it from automatic to manual about 3 years ago and this car has never given me a problem.....until...... now. So the battery is about 5 years old and it finally gave up on me a couple weeks ago, today I jump started and was going to go get a new battery but when I went to drive it it would sputter and die, when I pushed on the gas sometimes I could get it to rev up but most of the time it just stayed around 700 rpm sputtering. I thought maybe the batter just wasn’t cutting it so u pulled a good battery out of my 87 325i sedan and put it in but go the same result. Wondering if anyone had any thoughts or ideas as to what could be causing this. Any help is greatly appreciated.
Thanks
Both batteries are bad?
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I can try a 3rd battery but the second battery has given me no reason thinks it’s bad
Test both batteries at the posts with a voltmeter.
Take note of the voltage readings and post back.
I would also check your fuel pressure
No e30s again.
Once you disconnect power to the ECU, it’s very common for an I car to stumble around until the idle stabilizes. Mine (also an 87) does it every time I disconnect the battery. Once I drive the car for a while, the ECU must recalibrate it’s idle control circuits because it goes back to a normal, steady idle.
Last edited by msservices; 10-13-2018 at 11:45 PM.
First batter tested right around 10 volts and the second battery was just over 12v
Second battery might be okay, can you measure the voltage on the posts woth the car running? Should be higher than 12v. Also how long have you let it run in total since the 2nd battery was installed?
check your fuel pressure.
No e30s again.
Charge the battery overnight, compare voltage to this chart:
100% charge is 12.7v
I would also test fuel pressure.
If my memory is correct fuel pressure readings should be about 43~44psi.
Last edited by MIKYZZ4; 10-15-2018 at 04:19 PM.
There is no adaptive circuitry in any of the Motronic units found in the E30. I don't know what you're experiencing, but it isn't that.
- - - Updated - - -
Just to rule out battery/alternator issues, follow the instructions in this post https://www.bimmerforums.com/forum/s...5#post28741145
"Howdy, Folks!"
1986 Delphin 528e - Roof rack equipped lumber hauler.
1989 Zinnoberrot 325iX Sedan - I miss this car. (Deceased)
1998 Avus Blau 328iC - Someone else's project now
2008 Platinum-Beige X3 3.0si - Current project
2012 Alpine White X3 xDrive35i - My new snowmobile.
2020 Estoril Blue 440i xDrive cabrio - This car is a blast to drive.
With all due respect to what your saying about the Motronic circuitry, (which I know little of) I’m not the first person to observe, or write about, this happening when you disconnect a battery, and I myself have had it happen on more than one e30 325i year/model. When I say “must” that’s me assuming what I think must be happening based on the consistency of the occurrence. Whether it’s adaptive circuitry or not, it rectifies after driving the car for a short time. So having said that, what do you think is happening on my cars when I pull power from the memory?
Last edited by msservices; 10-15-2018 at 07:56 PM.
Here is some info included in the link that was provided:
https://www.bimmerforums.com/forum/s...1#post28759971
Last edited by MIKYZZ4; 10-15-2018 at 08:25 PM. Reason: Link
Those are excellent write-ups, but there is nothing in there explaining what changes when you disconnect power at the battery, which seems to be what happened to the OP? His battery goes dead, he puts in a new/used one of decent voltage, but the car doesn’t run right now. I’m still curious as to how long he has let the car run in total since he installed the new battery
OP,
Install battery(100% charged)
Run engine, try various rpm's
Perform stomp test
Post back with results.
Last edited by MIKYZZ4; 10-15-2018 at 11:27 PM.
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