Have had this issue for a year now, but stopped trying to figure it out until recently since my daily driver got totaled and I'm forced to drive my S2k as a daily for now.

Context:
I do have the clutch pedal sensor bypassed, but it's the same with/without the bypass.
Car started having this problem a year ago after not being driven for a couple months and letting the battery completely drain.
There is an aftermarket grounding kit installed and I've ensured that all grounds are firmly connected.

The symptoms are as follows:
Won't start immediately, I need to hold down the start button for a good 10-20 seconds before it'll start. When it does start, it starts fine. Once in awhile, it'll start normally without the 10-20 second delay.

Anyone have any issue like this? I'm thinking it's related to the battery/grounding kit because there was a period of time where it started completely normally and stopped starting normally immediately after I disconnected the battery (was unlearning the ECU).

 

This sounds to me like the fuel is draining out of the lines back to tank when it sits for a while, so when you try to start it, it has to pump fuel from tank all the way to front of car. Its like you ran out of gas, and now you've filled the tank, but car won't start at first.

Sometimes it doesn't sit long enough, or maybe its somehow temp related if fuel lines clear or not. So sometimes it starts normal.

I had this problem in my Audi. Twice. First time it was sticky injector, that would leak fuel into that cylinder, so fuel line pressure was gone. Replaced injectors, problem resolved for a few years. Next time it was fuel pressure regulator. But result was same for both. Fuel line pressure gone from sitting, so it took forever cranking to start. But then it ran fine.

Rent fuel pressure tester from AutoZone, etc. Let cae sit overnight, check fuel pressure at rail. An even easier test is next time it happens, before it cranks long enough to start, remove Schrader valve cap from fuel rail, and press the valve to see if fuel spurts out (eye protection!)

 

I'll look into that, but I don't think that it's fuel related because even after I get the car running, if I shut it off immediately and try to start again (fuel should still be at the rail), it takes 20 seconds. It's not isolated to cold starts only.

 

You didn't really say, but I assume you mean the engine cranks and turns over for 10-20 seconds, correct?

 

No, nothing for 10-20 seconds, then it'll fire right up in the normal 2-3cranks

 

Sounds like starter button maybe bad. Or there are still some grounding or high-tension wire issues.

 

forgot to follow up with this thread after i found the solution nearly a year later. the problem was that the battery terminals had built up crud on them. after using some sandpaper to the terminals and even the battery's posts to cut fresh mating surfaces, the car started trouble free for awhile. it looks as though after 4 years, the issue has returned but this time i think i'll just replace the 20+ year old battery cables.

 

Good result. I'd also check the connections of the ground strap to chassis and the positive leads to starter and alternator --- for similar contact issues.