PORSCHE TECHNICAL TOPICS

Technical problems solved

A few months ago I described within these pages how 997 Carrera owner Michael Frith benefited from an inspection of his car during an open day at the Dove House Motor Company, during which it was found that a replacement battery had previously been installed in such a way that it could have been venting potentially dangerous fumes into the cabin air intake. (The breather tube had not only been left off the new accumulator, but also trapped and thus decisively squashed beneath the casing.)

I was reminded of that while chatting more recently to Steve Mchale at JZM (jzmporsche.com) about modern DFI fuel injectors, and the resulting carbon deposits that can build up on the backs of the inlet valves in cars thus equipped. (See pages 72–76 of the June 2017 edition.) Inevitably we started talking about the astonishing complexity of all modern Porsches – although Steve, to be fair, sees that more as a sophistication that aids their maintenance and repair as much as I would view it as a possible hindrance – and then he proudly showed me the latest Porsche PIWIS III system testers that he and his technicians are now using. (Although they still have the older machines, of course, for those cars that still need them.)

‘It was another significant investment for us to make,’ he told me, ‘but if you are as serious as we are about working on any of the cars built after about 2008/2009 then you just have to have at least one of them. The machines – and we have two – are linked in real time via the internet directly to the factory in Germany, and give us access not just to all of the car’s systems and software, but also to every conceivable piece of technical information that you might need. Even to wiring diagrams that make faulttracing as easy as following an Ordnance Survey map!’

The new machines – each one about the size of a conventional laptop PC, and able to connect wirelessly to the car via Bluetooth – make JZM one of the few specialists able to ‘code’ new keys for the later vehicles, added Steve, and unsurprisingly that led us on to the coding of their electrical components in general. Fit something as seemingly straightforward as a new headlamp, for instance, and it will have to be enabled to communicate with the vehicle’s central system before it will actually work. And if you think that is Porsche taking the mickey, then consider this: you have to go through precisely the same rigmarole with even an item as basic as the battery.

‘To be fair, there is nothing physically to stop you buying an equivalent battery from whatever source you like,’ said Steve. ‘And it will start and run the car without any problem. But only the genuine Porsche item comes with the multi-digit number that, when entered in the car’s memory, allows the battery to “talk” to the main ECU, via the special connection on the negative lead, and without that there is no way of putting out the check light on the instrument panel. Features like the engine stop-start system will be disabled, too.’ Seriously? How long before – effectively as in the 991 already, and to a similar extent in the Boxster and Cayman – even the front-engined cars’ bonnets are sealed shut at the factory? You can see it coming, can’t you?

Unsurprisingly in light of their sophisticated electronic systems, the latest Porsches require even greater care than usual when working on any aspect of their electrical systems – and especially when charging a flat battery or using a trickle charger. In this 991, for instance, the device should be connected to the battery positive lead/terminal and an M8 screw threaded into this hole in the adjacent left-hand strut tower (arrowed). You might need a suitable tap gently to clean out the threads first, suggests JZM’S Steve Mchale. To jump-start this car, however (and that is recommended only in cases of dire emergency), connect your positive lead to the battery positive terminal, but then – and in this order – your negative lead to the point provided next to the right-hand strut mount (right)

JZM’S two new PIWIS III machines, one of which is shown here in the safe hands of proprietor Steve Mchale (above), naturally require a full understanding of their methodology and many features, but in a way make the staggering complexity of the later cars (almost!) as easy to deal with as updating your iphone. Operation is via keyboard and/or touchscreen and stylus, and the machine connects to the car via either a cable or this wireless device plugged in to the dedicated port under the fascia (right)

Modern Porsches – that is to say those built after about 2008/2009 – have this additional connection (above) to their battery earth leads. Essentially it allows the car’s charging system very precisely to monitor the condition and output of the accumulator, and even to disable individual systems that are not deemed safety-critical if it detects the voltage falling below a certain level – the engine stop-start feature, for instance. It can also allow rapid charging by the vehicle’s own alternator, briefly pushing up to 17 volts into the battery. Crucially, however, it will function only with a genuine Porsche battery, whose unique code number has been programmed into the car’s memory via a so-called system tester

JZM’S technicians always connect a ‘buffer’ to the battery terminals when carrying out any electrical work – essentially a highly sophisticated charger, in this case made by Bosch – and this is essential when the car is hooked up to the system tester. The ignition will be switched on, and many of the car’s consumer units in operation – and you certainly don’t want any electrical shortfall when tackling something as critical as coding new sub-assemblies