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jjdunning

525e cold start valve help & battery mystery

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Hi!

 

So... I've an E registration 525e that was built in December 1986. 

 

It doesn't always start (for reasons I cannot make sense of – further details below), which I am thinking is to do with the Cold Start Valve.

 

I've found differing reports/diagnoses around the internet (including from realoem.com) about where the CSV is situated. I was wondering if anyone on here can tell me definitively...

 

a. if this car *has* a Cold Start Valve

b. if it does, where it is located (I thought it was by the fuel tank – as my Haynes suggests – but my local mechanic says it's on top of the engine block?)

c. the right part number and where I can get one (emailed a few places and eBayers, but nobody has one so far)

 

Non-start nonsense – all ideas welcome!

There seems to be plenty of power in the battery (which is new) – the engine turns over but doesn't fire. Mechanic says there's spark.

Once I jump the car, it starts first time and runs fine. Can't understand how this happens if it's a fuel injection issue, but this is what happens!

I tried using a battery charger to boost the battery, but over a six-hour charge the battery level actually fell. Maybe all this sounds more like an electrics issue than a CSV issue – could be there's a power leak?

 

Just keen to know if any of these problems sound familiar and if anyone has any suggestions, really.

 

Thanks

JJ

 

Edited by jjdunning

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I'm 99% sure you doint have a cold start valve, motronic has temp sensors and richens he mixture.

 

I'd be checking all earth points and battery connections.

 

Failing that work through the no start guide i wrote.

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22 minutes ago, duncan-uk said:

I'm 99% sure you doint have a cold start valve, motronic has temp sensors and richens he mixture.

 

I'm not as familiar with the M20 as the M88, but isn't #9 the cold start injector?

 

http://www.realoem.com/bmw/enUS/showparts?id=4242-EUR-12-1985-E28-BMW-525e&diagId=13_1076

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No, I'm not convinced either. But that's the injector that fires when the coolant temp sensor says it needs to enrich the mixture.

 

To understand better, is the case that the car will never start unless it is jump started, in which case it then always starts first time? If so, as Duncan says a bad connection somewhere or the battery you have isn't rated to a high enough CCA level.

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I have owned the car for nearly three weeks. At first, it would start without needing to be jumped, but since then it has been 50/50 – on occasions where I have jumped it and then taken it for a long run, the non-start problem has been remedied for a day or so. I'd say I'm now at a place where it won't start without being jumped.

 

The previous owner replaced some relays and installed a new battery in December – since which time, it had started on the button for him without issue.

Edited by jjdunning

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This sounds familiar - I think someone else had a similar issue, although I'm buggered if I can remember who yet.


Duncan's "Motronic No-Start Guide" is pretty comprehensive, and would be useful for you to work through 1) to try to isolate the cause and 2) to get much more familiar with your car - it's pinned to the top of the E28 section.

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Have you done a basic battery check? Ie voltage off and then voltage running to check the battery is being charged?

 

Second is the battery being discharged? Boot light staying on or similar?

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