Jake924S

Hi Everybody! My First Post!


Firstly, I cannot explain how much the posts on this forum have already helped me diagnosing a no start problem on my 86 924S!! Your all bloody legends, especially Peanut! Thank you all.

Car is very clean, well loved UK Import. RHD. No rust or water damage from battery tray effecting the relay/fuse harness.. This car had $8000 spent on it by previous owner at AutoHaus Sydney (Australia's best Porsche garage) a year before I purchased and my Porsche mechanical did a check/service when I first purchased the vehicle and was blown away by how original and loved it had been.

I've owned the car for 6 months and she was running mint.

I parked her in my garage, three days later tried to start and just cranked, no fire.

Started searching online and discovered the forums and Clarke's Garage.

Went through Clarke's garage DME relay troubleshooting, tested relay with multimeter/power and seemed fine.
Had zero tach bounce, zero spark at plugs or dizzy (contacts seemed dirty so cleaned, cap/rotor looked good. All HVL are like new.
Power at coil.
Couldn't hear the fuel pump on hot ignition or whilst cranking (impossible to hear on my own) but undid hose clamp at fuel rail and ran hose to container, fuel spurted out when cranking.

Tested relay socket, Power at pin 30 constant & 86 when ignition hot.

Confusion and lots of forum reading at this point!

Charged battery overnight to 100%

Jumped the gun here .. focused on speed/ref troubleshooting. Crank sensor came out with some persuasion but Speed sensor was stuck hard in bracket, undid bracket with the breaky method (This was fun! NOT!)
They looked bad and I never did get the Speed sensor out of original bracket.

Ordered two new speed/ref sensors and new bracket. Installed with no issue,
Set appropriate clearance with .8mm washer. Cranked but No fire. (Still No Tach bounce)
Frustration! but No love lost with new sensors as the clips on my ref/speed sensor leads where hard and had completely cracked with half the plastic bit stuck inside the female side of the plug.
I haven't checked continuity from the pins to the DME/ECU plug as I don't really trust my multi-meter skills/electrical testing confuses me so at this point I'm assuming the DME/ECU wiring loom is okay (I would love to install the Lindsey Racing harness though).

Jumped Relay according to Clarke's Garage and bang, she started and ran perfectly!
(I should have done this first!)
Ordered new DME relay. Plug it in, cranking but no fire.

So I do some more electrical testing, clean earth point in engine bay as well as the two earth points next to the relay/fuse harness beneath dash. No Start.
Charge battery to 100%.
I read a post regarding no earth/ground to pin sockets 85 & 85b.. wrapped a wire around Pin 85 and ran it straight to negative terminal on my battery and BANG I see tach bounce on cranking and she fires/runs perfectly..

So after all of this it appears I'm not getting ground/earth? signal to the pin from The DME/ECU ? or should this be hard wired to a ground point on the chassis?

I don't know the sequence or technicals of how /when/if the DME decides to send this signal to the relay in order to complete the second relay circuit or what?

Can anyone please explain how this works and maybe give me some more troubleshooting tips to isolate whether its a ground /wiring issue or a DME/ECU issue.

Thanks!