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1:51 AM
Good Night Mech Head Grease Monkeys! :o)
 
 
9 hours later…
11:02 AM
Hello, the car is bmw 535d can faulty alternator's regulator to turn off the car randomly? If the alternator is overcharging or something?
 
11:45 AM
@AsenM I'm not 100% on this one.. but I have to say it's rather unlikely, and I'd expect all manner of weird electrical symptoms before it just turned the car off
guessing the injectors didn't pan out as a cause?
 
yeah we took out injectors and specialist checked them they are a bit dirty but ... nothing serious
theres the post of my friend
```Hello, i own BMW E60 535D Pre-face 2005 for 8 months till now the car has around 470k kilometers on the dash. So the problem, three weeks ago the car stalled twice, the first time on traffic light - restarted and everything was time after 2 minutes on the highway it stalled again with 70km/h. I took it to a guy with diagnostics and he told me to change the crankshaft position sensor. So far so good the next day after the change i started up the car in the morning everything was fine ... After 4 minutes on the exact same place the car stalled again but this time i had to crank a bit longe
 
hmm.. there's a few electrical gremlins there but the voltage regulator just doesn't fit with the behavior going away once the car is up to temp
has the crankshaft position sensor been checked/replaced?
 
we had 3 sensors swapped them out
but the error stays
i guess it appears once the car stalls/missfires?
 
hmm.. either a complete red herring or possibly wiring related
crankshaft position sensor still doesn't fit the overall issues though
bad ground maybe?
 
possible
 
11:52 AM
that would explain the scattershot of warning lights and electrical gremlins
and at a stretch it could be a connection that improves with the increase in temp - explaining it going away once the car is up to temp
random cut outs are often fuel starvation but it sounds like that's been throughly examined and debunked here
in fact the vast majority of the "usual suspects" have been gone through here
have you looked at the charging voltages?
if you're seeing erratic charging voltage then I'd say voltage regulator
if that's steady then as something a bit out of the leftfield I'd say bad starter motor (sometimes when they go they erratically draw too much power during cranking leading to all kinds of weird symptoms)
 
14.x is the charging voltage
 
and of course when the car is warm it's much, much easier to start so this sort of thing can go away once warm
@AsenM is it holding steady?
 
yes
 
@AsenM that would seem to rule out the voltage regulator IMO
otherwise that figure would be all over the place
wouldn't hurt to check the contacts out on the VRM (you'll be able to see if they are corroded) but I'd be shocked if it was the issue
what does the voltage show during cranking?
 
hmm didn't check the voltage during cranking it usually car starts pretty easy
 
12:10 PM
@AsenM if it drops excessively during one of the "difficult" cranks vs a normal one that would hint at bad starter
 
so how does the starter make the car die once its already running?
I don't see logic there
 
it's not exactly common but if it draws too excessively the resultant drop can send various electronics into a brownout situation.. but I have to admit I'm kinda clutching at straws here
there kinda feels like there's too much of a timelag between the starting and the cutting out for that to be the caase
 
sometimes it dies after 2-3-5 seconds
sometimes it last few minutes before dying
 
others it seems like it's several minutes later - which would have given the system time to recover
something tells me that when this finally gets solved it's going to leave people scratching their heads going "how the f##k did that cause that??"
 
i think it's some lose wire maybe crankshaft sensor
or one of the injector wires
 
12:19 PM
crankshaft sensor wiring is a possibility - doesn't quite fit with the warm up behaviour but not impossible it could behave that way.
injector wiring is another one - the cut out symptoms did scream failing injector (before those were ruled out)
 
well if it warms up it can get better connectivity
 
the other random gremlins though...
still makes me wonder about a bad ground
 
or maybe not good enough ground?
yeah same
 
IIRC they are in the boot on these (they are on LCI cars anyway)
 
what do you think testing this?
 
12:24 PM
@AsenM worth doing a continuity test to check
Disconnect the -ve battery cable and hook a multimeter (DC mode) to the battery terminals - you should get ~ 12.6V. Next, remove the multimeter probe from the +ive battery terminal and touch it to the terminal on the disconnected -ve battery cable. You should get a figure within +- 0.5V of the battery figure. If you get anything below 11.5V then it's got a bad ground somewhere.
 
sorry i didn't understand that quite well?
 
sorry
will break it down a bit more
 
why testing the voltage?
if i hook one probe on the - terminal and other somewhere on the engine or car chassis and check continuity?
or continuity
 
yeah you're essentially testing the continuity between chassis and battery
 
12:43 PM
so why would i need to measure voltage?
or you mean measure voltage between + terminal and chassis
 
1:06 PM
@motosubatsu
?
 
sorry.. was elsewhere and didn't see you last message
yeah you're comparing a known "good" ground - ie the negative terminal of the battery with the ground to the chassis
I appreciate I'm perhaps not explaining that particularly well
you can do the same thing by checking resistance
(if your multimeter supports that)
in which case you just leave everything connected - have one probe on the negative terminal and putting the other one on a decent grounding point, you should get a really low resistance figure if the ground wire is good
there's a really good series of vids on youtube that walk through how to test various bits like main ground, checking grounds for individual wires and so on
annoyingly I'm at work and YT is blocked here so I can't link
I think the username is dialfast or something like that
sorry it's been a while since I saw them!
 
1:23 PM
no problem thanks
I have some idea how to test them just wanted to make sure this is the best/fastest/easiest way
 
I'm not sure its the best tbh... it might be, it's just the only way I know
apologies.. I tend to run away from electrical problems as it's like trying to catch smoke in a sieve on cars :D
 
yeah same :)
what about 3pin connectors on injectors?
I know how to test the 2pin ones but 3? whats the deal there?
 
not sure on the pins for those tbh
 
1:39 PM
like one is constant 12v other is ground
and middle one is signal wire
but not sure how to check the signals
 
you could use a puncture probe on a multimeter to check the voltages? depends on how easy it is to get to the wires
 
signal will go pretty fast won't be able to trace it that way i think
i can check the 12v and ground but the signal .. hmm not sure i'm not electrician
 
@AsenM yeah it'll depend on your multimeter but I suspect it will be oscillating to quickly to properly check
not sure if ODB will provide the signal volts?
 
hmm it will but can it be trusted?
maybe i will need oscilloscope
 
2:03 PM
@AsenM possibly..scoping stuff will give you a very accurate picture
 
Yeah I might look for some DSO to measure the wires :)
 

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