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gerrymoore
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'Normally' it just starts like it should. Last few times I've driven it it was fine. Just been out to wash it and tested and it started perfectly. When it 'throws a strop 
" it cranks as though the battery is flat ..very, very slowly (uh uh uh uh)but does normally start the car. The next time, literally 10 seconds later, it can be perfect again 
. No lights showing and no faults on Carly. Just to say, the first thing I did with my last 3 BMW's was to program the start/stop to be off as I hate it!!
I've just tested the 'new' starter and it's fine. I'll see if I can get it fitted asap just to prove once and for all it's not the b***y starter.
Hotpony ...thanks for your input..I did try looking at the diagrams but they are a nightmare to follow..so many modules and all seem to be dependant on each other. The fault is so intermittent and yet I have tried almost everything ...I would think that a new battery (and well charged) and 12 volts on to the solenoid and it should just crank perfectly whether it starts or not. The symptoms of a flat battery is very odd indeed.
" it cranks as though the battery is flat ..very, very slowly (uh uh uh uh)but does normally start the car. The next time, literally 10 seconds later, it can be perfect again . No lights showing and no faults on Carly. Just to say, the first thing I did with my last 3 BMW's was to program the start/stop to be off as I hate it!!I've just tested the 'new' starter and it's fine. I'll see if I can get it fitted asap just to prove once and for all it's not the b***y starter.
Hotpony ...thanks for your input..I did try looking at the diagrams but they are a nightmare to follow..so many modules and all seem to be dependant on each other. The fault is so intermittent and yet I have tried almost everything ...I would think that a new battery (and well charged) and 12 volts on to the solenoid and it should just crank perfectly whether it starts or not. The symptoms of a flat battery is very odd indeed.
octo0072000
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could try a extra earth cable battery to engine block to see if it makes any difference
He already added a couple of extras
octo0072000
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missed that bit
octo0072000
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when it throws a wobbly does the dash lights dim ?
if so i would be looking at main battery cable issue as you have done the earths
if so i would be looking at main battery cable issue as you have done the earths
hotponyshoes
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'Normally' it just starts like it should. Last few times I've driven it it was fine. Just been out to wash it and tested and it started perfectly. When it 'throws a strop
I've just tested the 'new' starter and it's fine. I'll see if I can get it fitted asap just to prove once and for all it's not the b***y starter.
Hotpony ...thanks for your input..I did try looking at the diagrams but they are a nightmare to follow..so many modules and all seem to be dependant on each other. The fault is so intermittent and yet I have tried almost everything ...I would think that a new battery (and well charged) and 12 volts on to the solenoid and it should just crank perfectly whether it starts or not. The symptoms of a flat battery is very odd indeed.
The symptoms of a flat battery point to it either not getting the power to the starter or something else draining the power.
If I remember rightly the starter cabke is also connected to the alternator and I think you might have an electric power steering pump and the cable might run onto that as well. Either of those would be able to drain enough power under a fault condition to sap enough from the starter to give low/no cranking.
My money would be on corrosion somewhere along a connection on the main cable although I would expect this to gradually get worse until the point it failed to even try and turn over.
It would be easy enough to check if it was doing it every time but once every now and again is a bit harder to test!
I would start with a physical examination of the cables starting from the battery.
Maybe do it in a garage at night, put the heater blower on full and the headlights on main beam shining on a wall, start wiggling the cables around by hand and shake the battery around and have a pull on the terminals and battery to earth cable and see if the lights flicker or dim at any point.
gerrymoore
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Thanks again everyone for your thoughts........the battery is in the boot. I have replaced a couple of cables the one from the alternator to battery connector under the bonnet (£76.00 !!) and have checked most of the others. I haven't checked the main one from the boot as it's hidden mostly under covers...as you say though it would/should be getting worse and it isn't.
I haven't been well for months so as soon as I'm up to it I'll take another look....if I can fix it I can sell it as I've already gone and bought another car - another BMW
I haven't been well for months so as soon as I'm up to it I'll take another look....if I can fix it I can sell it as I've already gone and bought another car - another BMW
slim_boy_fat
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Lots of bits hiding there
https://www.realoem.com/bmw/enUS/showparts?id=NA72-EUR-06-2003-E60-BMW-530i&diagId=61_1760
I've read about problems caused by the BST, see post #4 here
https://www.bimmerforums.com/forum/showthread.php?2065814-battery-cable-broken-terminal
Might be worth checking out, any movement of or problems with cracking/splitting could cause your intermittent start problem. Just a thought......
gerrymoore
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After another sleepless night over this I have now come to agree that it must be a bad joint/break in the cables somewhere!! Can't see how the starter can be perfect 6 times and then not and then perfect?? I would like to know what 'latches' when I press the start button..if it's a relay then that could be the problem. The main lead from battery to engine bay is BIG see pic but may be worth changing (2nd hand about £50) .......... anyone fancy the job 
hotponyshoes
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It's not a traditional relay, the start button just goes to an ecu.
That stops anything happening if you press the start button when the start/stop is active or the engine is running.
Well, it turns it off rather than engages the starter if you are not moving.
It's a bit more than just wires and a relay as I expect you saw on the diagrams!
I would give everything a good wiggle first. I expect there is a joint or junction on that cable that is corroded rather than the cable itself.
There is probably some green fuzz in there somewhere that is building up and acting as an insulator. As the starter is trying to draw a load of amps its arcing across and welding itself back together and letting you start until the corrosion builds up again. Or, something that is just loose enough to break contact with vibration every now and again. This could happen at any time when driving but you will be getting power to the other end of the cable from the alternator so the car will run fine. You wont know notice until you try and start again.
That stops anything happening if you press the start button when the start/stop is active or the engine is running.
Well, it turns it off rather than engages the starter if you are not moving.
It's a bit more than just wires and a relay as I expect you saw on the diagrams!
I would give everything a good wiggle first. I expect there is a joint or junction on that cable that is corroded rather than the cable itself.
There is probably some green fuzz in there somewhere that is building up and acting as an insulator. As the starter is trying to draw a load of amps its arcing across and welding itself back together and letting you start until the corrosion builds up again. Or, something that is just loose enough to break contact with vibration every now and again. This could happen at any time when driving but you will be getting power to the other end of the cable from the alternator so the car will run fine. You wont know notice until you try and start again.
hotponyshoes
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What "latches" is a timer in the ecu that runs the starter for 15 seconds (or so) or until it picks up a "engine running" or "fault shutdown" code from one of the other ecu's.
Another way to test the main cable is tap a live wire directly onto the starter solonide and see if it cranks over but you need to know the car will not start otherwise for that test to be any good and yours sounds too intermittent for that.
Another way to test the main cable is tap a live wire directly onto the starter solonide and see if it cranks over but you need to know the car will not start otherwise for that test to be any good and yours sounds too intermittent for that.
gerrymoore
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Just a quick update..went out with the wife Sunday afternoon to a shopping centre about 15 miles from home. Stopped the car and waited (patiently) for her to come out of Primark - about 20 minutes. Went to start the car and nothing! Just one 'uh' and that was that. Got the other battery out the boot and put jump leads from this battery to the jump connectors under the bonnet...nothing just one more 'uh'. Called a taxi and £12 later was at Chester station and got train back home ..over an hour and half altogether.
Went back in wifes car next day and car went 'uh' but then 'just' started. Drove it back to the BMW indy gave him the 'new' starter and basically said don't want it back until it's fixed ..the wife wants me to scrap it!! Watch this space .... could be a really nice 2014 BMW Msport going very cheap.....
Went back in wifes car next day and car went 'uh' but then 'just' started. Drove it back to the BMW indy gave him the 'new' starter and basically said don't want it back until it's fixed ..the wife wants me to scrap it!! Watch this space .... could be a really nice 2014 BMW Msport going very cheap.....
dobbslc
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I'd get him to check the injectors aren't leaking into one of the cylinders. The 'uh' might just be the thing struggling to turn over with a cylinder full of fuel and it eventually gets past TDC and spins over freely. If there's any leakage into the bore it will really struggle to turn it.
Got to be worth a check after all this grief!
Got to be worth a check after all this grief!
gerrymoore
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I'll mention it to him although would a faulty injector be intermittent? As said, it doesn't do this every time..... unfortunately.
hotponyshoes
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The injector might not be intermittent but you only have a small chance of that cylinder being in the right place on a compression stroke when you are about to start.
