The Pitstop

1:51 AM

Good Night Mech Head Grease Monkeys! :o)

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?

motosubatsu

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?

AsenM

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…

motosubatsu

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?

AsenM

we had 3 sensors swapped them out

but the error stays

i guess it appears once the car stalls/missfires?

motosubatsu

hmm.. either a complete red herring or possibly wiring related

crankshaft position sensor still doesn't fit the overall issues though

bad ground maybe?

AsenM

possible

motosubatsu

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)

AsenM

14.x is the charging voltage

motosubatsu

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?

AsenM

yes

motosubatsu

@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?

AsenM

hmm didn't check the voltage during cranking it usually car starts pretty easy

motosubatsu

12:10 PM

@AsenM if it drops excessively during one of the "difficult" cranks vs a normal one that would hint at bad starter

AsenM

so how does the starter make the car die once its already running?

I don't see logic there

motosubatsu

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

AsenM

sometimes it dies after 2-3-5 seconds

sometimes it last few minutes before dying

motosubatsu

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??"

AsenM

i think it's some lose wire maybe crankshaft sensor

or one of the injector wires

motosubatsu

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)

AsenM

well if it warms up it can get better connectivity

motosubatsu

the other random gremlins though...

still makes me wonder about a bad ground

AsenM

or maybe not good enough ground?

yeah same

motosubatsu

IIRC they are in the boot on these (they are on LCI cars anyway)

AsenM

what do you think testing this?

motosubatsu

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.

AsenM

sorry i didn't understand that quite well?

motosubatsu

sorry

will break it down a bit more

AsenM

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

motosubatsu

yeah you're essentially testing the continuity between chassis and battery

AsenM

12:43 PM

so why would i need to measure voltage?

or you mean measure voltage between + terminal and chassis

AsenM

1:06 PM

@motosubatsu

?

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!

AsenM

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

motosubatsu

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

AsenM

yeah same :)