This is my pet project, a Porsche 928 S4, 1998 around 60,000 miles on the clock
Needless to say, she goes like stink with a 5.0 litre V8 engine knocking out 320bhp. When I was working on the cruise control to get it operational again, I had to remove the ECU from the passenger foot well and was pleasantly surprised to find that it had a superchips sticker attached which means it probably has had an upgrade in the past and that should improve mid range drivability and torque with an additional 10 bhp.
As with any car 22 years old, there are plenty of things to do to get her in tip top condition and make sure everything is functional. Below is my high level plan for what needs doing, as time goes on many of these headings will be broken down to more detailed tasks.
Making a start
First up was getting some basic electrics sorted out. When I got the car the sunroof did not work, but with a replacement switch from ebay this was soon sorted and the sunroof was back in action. Getting it open I greased up the runners after cleaning it all out and giving the rubber seal a good clean and dose of lubricant to moisturise it.
Next up I traced and cleaned all the earth points I could find. There are lots of different earth positions on the 928 typically with brown wire terminating in a brass ring spade connector. These can corrode and tarnish and there is no substitute for a dose of baking soda and a pink pencil eraser to get rid of the grime and restore the shine. Many illogical electrical problems can be caused by poor earthing. The 928 has a bad reputation for having problem electrics but certainly as a start you should make sure all the earths are clean and properly terminated.