Kevin groves

Hi all.

firstly hello to you all, I am a newbie here,
I recently acquired my dads 928 s4 (1987) due to his Unfortunate passing.
the car is in good condition and up to now everything works perfect.
i want to keep the car as it has been in our family a fair few years and has much sentimental value.
Its an awesome car, I fully appreciate why you guys like and enjoy these cars.

i have a problem that has just arisen....
when I turn the ignition on the dash warning lights do not come on, the car will turn over but will not fire up.
ive also noticed then rev counter flicks up then back off again.
this happens frequently, but on occasions it works as normal, turn key, all lights illuminate and it starts fine.
when it is running it runs fine, another strange thing is sometimes when it’s running the battery voltage gauge drops to zero then after a few seconds the engine cuts out, almost like the fuel pump has stopped.
the car has been fine up until now.
The only things I’ve been working on is weekend is replacing all 4 brake discs and pads, I also jet washed the wheel arches and re-wrapped the abs sensor wiring due to broken down insulation. Changed oil and coolant and Air filter. But I can’t think this would cause an issue.

dies anyone have any ideas or could point me in the direction of what to check out?
thank you all.

SteveG

Just curious, Southampton, UK or Long Island ?

You don't mention a battery maintainer, so I'm guessing the batt is down. Most of us keep a maintainer on it. Even it it shows 12.5v, that may not be enough is the batt is old. The electr sys is very demanding and usu this shows first as what you are experiencing.

Kevin groves

Hi there.

im in Southampton U.K.
i have a battery maintainer, battery is only 2 months old
when I turn the ignition key and the lights come on as normal on the dash it then turns over and starts fine.
its very odd, as most of the time the dash lights do not illuminate and it won’t start, but occasionally it works fine.
thanks

Shark2626

If you have a set of battery jumper cables (I have no idea what they are called in the UK), connect one of the jumper cables to the black (-) battery connector and connect its other end to a bolt on your shock tower in the rear hatch to the left of the battery box, and see what happens. What you would be doing is bypassing your car's ground strap and grounding the battery instead using that jumper cable. If that solves the issue you need to look at your ground strap.

Kevin groves

Hi there.
thank you for your replies guys.
ive just tried that now. No difference,
one thing that is interesting is.....
I turn the ignition key to the ignition on position.
But I have no dash lights, then sometimes after a good 20 to 15 seconds the lights appear and it will start.
very odd this one

ddire333

ignition switch or connector is next place i would go. It easy to reach up under the dash and move it / press the connector on while turning the key, and see if that changes the dash behavior.

j.kenzie@sbcglobal.net

Agree. Ignition switches can go out fairly commonly.
Good luck,
Dave

Kevin groves

Thank you for your advice.
I will get a switch ordered now. Go for that 1st.
does anyone have a guide on replacing the ignition switch please.
thank you all

Shark2626

Sure, you are actually removing the pod, that's the bulk of the process anyway. The ignition switch is held in by a single philips head bolt (IIRC), you'll see after the pod is off. You can follow Dwayne's Garage Pod removal writeup. A word of advice, read it through to the reinstall process before you start, he inadvertently removed one extra bolt that wasn't necessary and it complicated the reinstall. So try not to remove that 5th (IIRC) bolt that secures a bracket that accepts one of the four bolts that you will remove. Here is the link:

http://dwaynesgarage.norcal928.org/P...Repair%20I.htm

Just curious, is the car consistently starting now when you wait the 20-30 seconds for the dash to light up before trying to start it?

ddire333

I would suggest you do some testing before replacing, there are plenty of other possibilities for your issue, its just the ignition is first to rule out.

Kevin groves

Thank you for that. It will be a massive help.
ill have a good read through before starting to remove the pod.

yes as long as the dash lights are illuminated the car starts just fine.
very intermittent, sometimes when I turn the key the dash lights perform as expected, the car starts fine.
other times I turn the key, the Rev counter flicks up then down but no dash lights, then car won’t start,
it’s almost like the ignition switch isn’t switching the ignition system on but it will still crank over,
what’s odd is if I leave the ignition switch on, usually after a 15 second or so delay the dash lights come on, (I also hear the relay in the fuse box click), then it will start. This is also intermittent though,
also sometimes when it works correctly (dash lights on and I start the car), suddenly after a few seconds or sometimes a minute the dash lights go off and after a few seconds then engine cuts out, it’s all very odd.
I’m hoping the new ignition switch will sort this,
Im very new to the 928 so unsure where else to look from the switch onwards.
so fingers crossed,
I doubt myself too as it happened directly after I did a oil and coolant service and swapped the brakes out.
but I can’t think of anything i would have done to cause it. More just bad luck I think.
Thank you all.

Kevin groves

Guys what other tats would you advice from your knowledge
thank you

Majestic Moose

Replace the relays stamped "53" in the CE (central electric) panel in the passenger footwell. They can cause all kinds of issues and are inexpensive to replace. Start with the X-bus, starter, fuel pump, and LH relays. Even if they are not the cause of this specific problem, chances are that they will become one soon.

If you do not have a fuse chart, see this one here. https://rennlist.com/forums/928-foru...l#post11114820

The part number is 141.951.253.B. Purchase them from a reputable shop, genuine Porsche, Bosch, VW, Audi, as there are Chinese counterfeit parts out there.

rgs944

Probablely helpful to this thread if anyone would have a link to the annual ground cleaning and maintenance?

Kevin groves

Thank you all for your help,
I have an ignition switch and some number53 relays on the way,
if anyone has a ground maintainance link they could share that would be great

again thank you all for your help