charge trek VI - 'I'm losing my mind'

[tim eh?]

Tim... gotta stop this problem!

1. Belt tensioner fault. Not tight enough would cause problem.

2. Bad ground cable at the battery and starter.

3. Bad alternator... Eliminated

4. Bad battery... ELIMINATED

5. Bad starter...

6. Bad fusible link?...

7. Instrument cluster board prone to farting.

8. Previously installed alarm system... 'fixed' but I still haven't ruled this out.
*- i think there are still some wires for this behind the stereo.

9. Engine electrical system?... brought this up once but nobody commented.
whacked ignition coil or something? I have no idea myself.

10. A/C system? ... can I defuse it?
This would be a good one... you know... i only just thought of this but there is a belt (that does work) on the a/c system (that doesn't work). i guess i might want to take that off. could that matter? also... isn't the aux fan supposed to turn on at a certain temperature? I can get it to run with direct current, I think the 2-temp switch is just fried.



Today - New Battery In. No change in symptoms whatsoever.

Tomorrow I will replace the battery to chassis and engine to chassis grounds, also the fusible link. Will check continuity from alternator casing to engine block. And I will throw in my spare white-backed cluster. Then I will check to see if it loses charge overnight, but I won't be confident of the readings for a couple of days. Guess I should redo wiring to starter... I haven't examined those really any tips? Are there kits or anything like that?

If bat is losing charge, I will suspect starter shorting out somewhere, and will install an inline fuse to see if it blows overnight.

starter is ugly, hmmmm i've replaced everything else...

Could somebody check my m20 alternator belt routing please? pic1 pic2 pic3 If I routed that wrong I will be embarrassed but so very happy. It's tight, really... it's really tight... I have tried it at different tensions and it doesn't change anything.

The main clues are whether the battery still loses charge overnight and..
***When cold the system charges fine... great ... 14.0V+ with absolutely every button pressed that can be pressed.... for the first 2-3 minutes...
then it drops off a cliff to below 12.0V and stays there. (temp guage has moved +/- 1/10th of it's range) I really have to turn everything off then to get the voltage back up but then I can run a medium load (lights, no defrost, heat on 2, radio) ok.

Your ten minute trip with all your electrical loads would tax any charging system..its that simple .Get the best battery you can get that is the proper size.See if you get the 150 amp alternator too next time

+1

Your battery was on it's way out because it isn't getting a good enough charge. The voltage dropping like it is when you've got that many things electrical running is telling you that the alternator isn't putting out enough juice to run everything and charge the battery.

Wonder how complicated it is to retrofit the battery location to the trunk?

Guys I have considered this a lot and I really am not qualified to argue this point with anyone, but it doesn't make sense to me. My old (probably 20 years old) 115A alternator charged everything fine, I would have noticed - I didn't have a problem like this all winter and I was using all the power quite a bit. Anyone have an idea how many amps a fully loaded system would use? I'm guessing 20-30 amps? but I haven't a clue really. But I don't believe that the stock charging system would be designed to operate that close to capacity even with all the buttons pushed... but maybe I'm totally wrong about this. I'm thinking about wiring an ammeter into the circuit but you have to do that in series and I wonder if I'd have to reroute a whole pile of thick wires into the dash. (not interested...) But I think with 3 different alternators and 2 batteries, if the problem was there then there would have been some variation in the symptoms, and really it does the exact same thing every time.

There is a cd changer under the seat and often an entire string quartet in the trunk so it's a no-go as far as battery relocation, as much of a joy as that would be. And still, I think putting a giant battery would just alleviate the symptom not the problem. A stock car really ought to run ok on a brand new stock battery/alternator combo, seriously, it ought to power the rear window defroster, no?

Thanks tho, please argue the other way I really appreciate your opinions!




One cool thing about all this is that even though I have some experience with musical instruments, amps, computers- that kind of thing, I'm still pretty much all newbo and I have suspected all the wiring work I have done myself since getting the car, but so far all of it has turned out to be ok. (haven't gone behind the stereo yet) Still... right now the possessed car is winning...

[Claude]

[QUOTE=tim eh?
The main clues are whether the battery still loses charge overnight and..
***When cold the system charges fine... great ... 14.0V+ with absolutely every button pressed that can be pressed.... for the first 2-3 minutes...
then it drops off a cliff to below 12.0V and stays there. (temp guage has moved +/- 1/10th of it's range) I really have to turn everything off then to get the voltage back up but then I can run a medium load (lights, no defrost, heat on 2, radio) ok.
QUOTE]

Tim you summerized the essential here. I think that we may now trust both your new battery and alternator and you're right they should easily do the job properly.

Normaly such voltage drop could be signs of either bad cell within the battery (excluded now) or bad intermittent alternator voltage regulator (exclude too now). I would say that this major voltage drop (from 14 to 12 volts) is due to a heavy / abnormal load that suddenly appears from where ?? that's the question ! Or bad grounding (intermittent) in between negative battery pole and the alternator.

The starter connections does not look good at all, but your starter does it's job OK and is out of the circuit (received no current) when the car is running, i would forget about it.

Your A/C compressor has a electrical clutch that does'nt seems to engage, chances are that's because your A/C has loose it's gas in such a case a protection system / switch enable the compressor to operate (compressor protection), so the problem is not there.

Good idea to read the total load the battery have to drain when the car is running, so equiped you'll be able to see if it's really and extra load that the battery has to take after 2-3 min of normal operation (if not, it's only a volatge drop so the grounding system could be the culprit). But to do so easily that's a clamp on current meter that you would need.

Don't give up !

[bad_manners_god]

I may be way off here tim, but clean your ICV, Idle control valve.

Reason: The ICV compensates for accesories, power steering, ac and anything else electrical by increasing the idle thus charging the alternator.

Also, 2 weeks ago I was working on my friends turbo neon and we've installed Megaquirt ECU into it and took away the spark and fuel control from the stock pcm and we left the IAC (Idle Air Control) to control the idle except because the stock pcm lost alot of it's inputs the IAC was going nuts, opening from 1200 to 2100 to compensate for nothing.

Solution: Unplugged the IAC, turned on all accesories in the car and adjusted the idle with the stop screw on the Throttle Body. Idles at 1100 perfectly now.

I'll keep thinking.

EDIT: Maybe test 9 on the OBC gives false readings after 2-3 min of operation, have you confirmed with a Multimeter when the Voltage drops?

EDIT 2: Maybe this will help:

[bmwrp8]

unhook connector from alarm module, check wiring that goes to alternator. see what happens or if your car has wiper pressure adjuster ( sorry don't really know whats it called) if its grounded or busted it draws power from the batt.even when off.. just disconnect the system but i guess not all e34's has it i guess only e32's but if you have, it might be the culprit. http://bmwe32.masscom.net/dutch740/wipertensioner.htm

[sal_park]

ok, been thinking about this.

As suggested above *something* happens at 2-3 minutes in which causes low voltage. What about this for a possibility:

1) The car has been sitting overnight, and is stone cold.
2) Obi-Wan ( ) starts the car.
3)The car does lots of stuff to keep the engine running smoothly during the warm up phase - raises the idle, uses extra fuel etc etc. End result is the idle is smooth and throttle response predicable because the idle has been raised by say +300 rpm above normal idle.
4) At somepoint later in the warm up phase (say 2-3 mins), the senors say, ok the engine is now warm, we can drop the idle back to normal, and so it goes back to the normal of say (guess) 800 rpm.

Could it be this is the point the system voltage goes from 14v -> 12v ? What I'm thinking is the alternator is turning off because the the engine is idling too low.

AFAIK, with all cars the alternator will only start to work above a given engine speed. If the engine ever drops below that speed (say for example 500 rpm) the alternator will cut out and only turn on again once the engine speed increases past the minimum. Obviously the alternator light *should* come on if this happens, but given the instrunment display is a little doddgy, what's to say the sensor light for the alternator light is operating correctly ?


I would suggest that:
< 12.5v is not charging
> 12.5v is charging

Tim, can you try the following:

1) get the car in a state so it will be showing a system voltage of ~12v when running (i.e. bad).
2) play with the throttle to try and see if there is a particular rpm that the system voltage jumps to ~14v, bearing in mind that the engine speed on the way up may be quite different from the engine speed on the way down, so it could be: not charging 800rpm, (increase revs) starts to charge 1200rpm (decrease revs) stops charging 1000 rpm.

What speed does it idle at when warm?

Is it an auto ? If so , what speed does idle at when warm in N and in D ?

Perhaps bad_manners_god has hit the nail on the head suggesting looking at the ISV ?

sal

[Ferret]

There's something very wrong here... what speed does your car tick over at?

Sal I think has a good idea, if you rev the car the voltage should jump up at some point. If it doesnt, the only thing I can think of any more is that all three alternators you've had have had the same batch of replacement regulators in them... meaning all three alts were bad.

The only other thing that would cause it to stop charging like that is a dip in RPM combined with a bad supply voltage on the field coil terminal.

Do the following tests:
Set your meter to volts, and clip one lead to the battery positive terminal, and the other to the B+ post on the alternator, run the car and see if anything shows up. In all states, IE first start while it's charging, when the charge drops off and while you're revving the nuts off the car.
Do the same test again, but measure the voltage between the alternator casing and the battery negative terminal.

If you get a voltage doing either of these tests, there's a high resistance somewhere...

[Tiger]

No... not plausible. What is plausible is the belt is not tight enough that the alternator slips... and thus reduce the voltage.

[sal_park]

No... not plausible.

Which bit ?

[sal_park]

as regards the tension in the alternator belt, I would expect that you should be able to push/pull the belt about 5/8 inch up/down when holding it in the centre of the longest span between 2 pulleys.

[Ferret]

No... not plausible. What is plausible is the belt is not tight enough that the alternator slips... and thus reduce the voltage.

My V8 does it... at idle with full load it'll only produce 12.something, give it a few beans and it'll perk right back up to the 14 ish mark. Belt's not slipping either.