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Engine Cranks But Wont Start

I’d agree with Dave’s comment re the battery Nick, especially if you’re getting other warning signals which is typical of what happens when the battery condition is marginal even though it’s cranking the engine.

If you can, check the quiescent voltage which should be around 12.5V or more. The Green Flag tech ought to be able to check the battery condition for you or maybe can remove it and take it to a local battery supplier who should do this for you FOC.

Jeff

 
I have an 85Ah battery on the car, Bosch is this the right battery?? for a Cayman S Sport 3.4 Litre??

BR

Nick

 
Nick,

From memory I think on my 987.2 CS it’s an 80Ah Moll battery, so your Bosch should be fine and depending on type they’re guaranteed for quite a few years if you can establish when it was fitted.

Jeff

 
I would think so, my 981 CS PDK had an 80Ah / 800A EN `cold cranking rating` item

What EN or CCA rating is your Bosch ?

 
IMG_6337.HEIC
The Battery is a Bosch S5 010 - 85Ah - 800A (EN) _ purchased it on 30.03.20

Interestingly though I had the charger on it over night and was fully charged, its now only showing 3 lights on conditioner??

 
That’s a high quality battery with a 5-year warranty Nick and I wouldn’t have thought that it’s the source of your problem given that it’s only a year old, but you never know since your car’s probably had very little use this past year and it would be a good idea to get it checked for peace of mind.

Anecdotally, if you’re using a CTEK MSX 5.0 battery conditioner there’s been quite a bit of forum chatter saying that it takes quite a long time to indicate “fully charged”.

Jeff

 
Morning Jeff

Sorry for the late reply, I have found the concern, the 15amp fuse keeps blowing for the injectors so there is a short somewhere?

Nick

 
Hi Nick,

Yes, sounds as though that could be the source of your problem but the difficulty is finding out where the short is if the fuse keeps blowing. If it’s just a single injector I think you’d expect the engine to run but since it’s not then I reckon the problem must be upstream … a dodgy cable or maybe a control module?

Sorry, can’t help beyond that, and if there’s nothing obvious on inspection I think that it’s going to be a recovery job either to your Porsche specialist or an auto electrician.

Jeff

 
Nick7602 said:
Morning Jeff

Sorry for the late reply, I have found the concern, the 15amp fuse keeps blowing for the injectors so there is a short somewhere?

Nick
Click to expand...

Sounds to me like classic DME relay failure .. crank but no fire is exactly that. You can try reseating it, give it a good shake / bang, but download PET and get yourself a relay quick ! Good luck over Easter ..

 
MoC2S said:
Nick7602 said:
Morning Jeff

Sorry for the late reply, I have found the concern, the 15amp fuse keeps blowing for the injectors so there is a short somewhere?

Nick
Click to expand...

Sounds to me like classic DME relay failure .. crank but no fire is exactly that. You can try reseating it, give it a good shake / bang, but download PET and get yourself a relay quick ! Good luck over Easter ..
Click to expand...
That may be a bit “old-school Porsche” Maurice. [;)]

Not sure if it’s applicable to the later water cooled F-6 cars like the 987.1 Cayman, but you never know with all the interconnected and complex electronics on cars these days and the most efficient way forward is to get some diagnostics on the job for guidance and to avoid swapping components willy-nilly.

Jeff

 
Good afternoon lads and what a gorgeous day to, out of interest how do I get to the Relays?.....if it is a relay and I can replace it...... maybe I can get the old girl out and have some fun

 
Nick,

My somewhat tongue-in-cheek response to Maurice’s reference to DME relay failure relates to the air-cooled 911s and I’m not sure that it’s applicable for our water-cooled cars.

If it’s of any use here’s a fuse listing which should be applicable for your car:

https://www.porscheclubgb.com/forum/tm.aspx?m=721338

There could be other relays on the engine bulkhead which service the engine itself.

Jeff

 
Hi Jeff

Thank you your most kind, however I have checked all the fuses and all are ok, so still no joy at the moment sadly

Nick

 
Nick Row D Fuse 7 would also appear to power the ignition coils. A short in one of those may be an issue. they are not known for robustness, although they do lead a hard life. Usually the car will run, albeit roughly, if one coil is out, but if that same coil is shorting then the result would parallel your experience.

 
Hi John

Yes Fuse 7, 15amp is the one that keeps blowing......I have noticed a couple of fuses the wrong ampage in places, but all fuses now are correct......have changed coil packs 4 & 6 because of a slight misfire

Nick

 
Motorhead said:
Nick,

My somewhat tongue-in-cheek response to Maurice’s reference to DME relay failure relates to the air-cooled 911s and I’m not sure that it’s applicable for our water-cooled cars.

If it’s of any use here’s a fuse listing which should be applicable for your car:

https://www.porscheclubgb.com/forum/tm.aspx?m=721338

There could be other relays on the engine bulkhead which service the engine itself.

Jeff
Click to expand...

I am / was confident that my suggestion was in the correct systems area of the car, air and water cooled engines do not differ in the ignition department, other than perhaps coil packs being utilised. This diagnosis seems to have been correct.

cheers, Maurice

 
Nick,

Since fuse F7 appears to be dual-purpose - ignition coils and injection valves - clearly the fault could be with either and as John says the coil packs are known to be troublesome, particularly on higher mileage cars. If you’ve only replaced two of them the chances are that the others could be marginal and it’s possible that one has failed and is shorting-out.

If you’re really keen I suppose you could disconnect and check individual continuity on each coil pack and injector or until the fuse stops blowing to find the offending pack/injector circuit.

Jeff

 
Hi Maurice and Jeff, Can I just say Maurice your input was and is very much appreciated, you along with jeff, John, and others who have had an input to my concern shows to me what a truly great club we are, where else would you find such friendly help and advice, its very much appreciated

I will recover the old girl to a specialist on Tuesday, thank you lads have a super Easter Holiday all of you.

Kind Regards

Nick

 
Good afternoon Lads

Can anyone tell me where the DME relay is? is there more than one relay for the DME? how do I replace and what is the process for replacement

Thanks Lads

 
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