Engine Intermittent Starting & No Starting Tip
 

After going practically through the entire system of my 84 928s, I finally isolated the cause of the intermittent engine starting I'd been suffering through for many months. It turned out to be a temperamental electronic fuel injection relay that would sometimes work and sometimes not...and lately, consistently not which made it easier to detect. I discovered this as I touched each relay while turning on the ignition but felt no click emanating from the EFI one. Replaced with a quality German 12 volt 30 amp 5 pin relay, it started right up!

Gabriel,
Some time back, I had the exact same experience. Can't remember all the things I checked and changed, but it turned out to be the same relay. Car has run great ever since. Good luck !!

I checked all systems and sensors, it drove me nuts not finding the culprit. It deemed the car unreliable for traveling anywhere, remaining in the garage until that "aha!" moment arrived where I could say that was the issue. I suppose these relays wear out after so many years even if the car isn't driven much.

Good catch!

Update: The engine continues to start as it should without issues. I can confirm the efi relay was the culprit all this time!