Tom M'Guinn

Next time it doesn't start, look to see if the factory boost gauge goes to 1 when you turn on the key. If not, then chances are your DME/KLR are not getting power for some reason (bad ignition switch, bad alarm, harness issues, etc.). If the boost gauge goes to 1, then you are probably getting power to the DME and the issue is more likely an engine management thing like cracked solder joints in the DME/KLR (which don't always respond to the kick test)...

mdj577

Good golly, this must be one of (or the) most persistent and frustrating problems for us “new” owners. I am going into nearly 2 yrs of ownership and still having this intermittent problem. DME relay is now new. Last no-start there was no-tach bounce. Going to try wiggling the ref sensor wires next. After that I guess it’s time to look at the DME itself and maybe try the re-soldering advice you guys have offered.

At this point I have to give all a thanks. You guy have been extremely helpful.

--This car is so damn good when running but, I want to throw it in the trash when not. Definition of addiction?

numbskull

Ha, boost addict? I totally know this frustration since my 86 went through the same issue. Before hitting it with a hammer here is my list of stuff I had to go through.

- Clean ref sensor connectors, used a tiny screwdriver to bend the contacts out, scratched the male connector pins to remove corrosion.
- removed all ground connections from the battery and wire brushed them all. Replace them if you can
- it took about an hour and a half to remove the dme and solder all the suspect joints with nicely fluxed new solder. Keep an eye on transistors, resistors and anything that is not very shiny or suspect cold joint.
- Check the pins on the dme harness to make sure nothing is bent. Carefully bend any pins back to proper place with very small screwdriver. I use a product called cramolin on all low voltage electrical connectors.
- dme relay replacement
- At one point I used an extra ground strap from battery to engine and chassis to rule out ground.
- Replaced cap rotor and coil, plugs
- Check and cleaned all connections to maf
- Adjusted tps properly and cleaned connections
- sprayed the ignition key hole on steering column
- Checked all grounds on column, and rear grounds near fuel pump, scraped connectors
- Checked all visible wiring on engine harness and wrapped up areas exposed where sheath was torn
- Check fuse box for and partially disconnected wires underneath
- Charged battery every time it would not start to full
- kept an eye on fuel pressure during condition

In my case the issue went away after scraping ref sensors pins and all grounds in no real particular order though I think this entire list overall helped a lot. Every other year it came back and same ref pin scrape with electrical lube fixed it long term. It seems cursed but it's just old and in need of fresh wiring in as many critical areas one is able to spend on. My old 77 280z had gremlins far worse than the 951. The Japanese design for electric components were over complicated compared to 86 Porsche.