This is a long shot here.

I have an S5 with an S4 HPB motor, 120amp alternator, battery relocated, haltech E6X, apexi avcr, apexi turbo timer, 7 gauges (boost, temps, pressure, etc.)

Here's my problem. The electrical power in my car shuts down randomly. While parked or driving, the power just randomly shuts down. What I noticed is that when I'm parked, I close my door and the turbo timer blinks. So right now to start the car, I have to hold the key in the crank position and close the door at the same time and magicly everything works. But then again I leave it parked for an hour and the problem comes back.

I know it's not the door switch in the B pillar that's the problem because the car needs to be shaken or needs a good shot from closing the door to even get the turbo timer to blink.

Battery and alternator are new from 4 months ago.

Has anyone ever had to deal with this sort of problem of heard of it ?

 

Sounds like a loose connection. check your main fusebox connectors etc.

Are you blowing a specific fuse now and then?

 

When the car dies or can't be started w/o slamming the car door do things such as the wipers, turn signals, horn, radio still work? If so you "might" have a faulty ground at the Main Relay. Do test this possibilty you would disconnect the 4 wire plug at the relay and jumper the White/Red wire to Black/Yellow and White/Blue to the Black/White wire. Doing this will bypass the relay but don't leave the jumper wires in place for a long time as it will eventually drain the battery.

And perhaps you can in detail illustrate how you have your turbo timer wired up.

The ignition switch might also have a rather loose connection and the alarm system, if equipped, located in the CPU might be problematic.

 

check that big "main" fuse... the one thats bolted in.

I blew it one time and it would sometimes make contact, and sometimes not... I coulden't even see that it was blown.

 

Problem found... Bad ground wire

 

where Roman?..just curious as to where the bad connection was coming from.

 

Ground wire from the battery

 

I was going to say check the main ground cable since the battery was relocated. Most likely cause of that kind of issue.