Weirdest electrical issue yet

[michel3171]

Well, after reading trough alot of the forum posts, nearly reaching the stage of driving my E53 X5 into a wall, I've decided as a last resort to create an account and ask for help. Im Michel, 23yo and live in the Netherlands.

Background on the car:

E53 X5 2003 (pre facelift) with the M57D30 engine. Bought the car with a broken engine (crankshaft/rodbearings gone), and replaced the engine with a very low mileage one, together with the gearbox. Replaced some gaskets and fluids, and the car drives without any mechanical issues.

ELECTRICAL ISSUES:

Since I've had the car, even with the old broken engine, the battery light would always randomly flicker. It still does, even with a new alternator. Battery reads 12.5 volts, so should be good aswell.

Depending on how much load the engine has/amount of throttle applied, the light and issues change. At a standstill, with engine off, all electrics work fine without any battery lights. At idle, 95% of the time the electrics work fine, and almost no battery light.

When applying full throttle, the following symptoms occure:

Battery light flicker/constant on
Power windows dont work, if they were in the process of rolling down they will stop doing so
Sunroof doesnt work, same as power windows
Speedometer stops climbing, just stays in the same spot untill throttle is released, then slowly climbs and suddenly jumps to the right speed
Wipers dont work, when mid-wipe they will also stop.

When applying slight throttle, the symptoms are the same just more intermittent.

I've been driving around with my laptop hooked up (INPA), and with the secret menu displaying voltage. Both devices show approx. 13.8 volts when driving, with no changes in voltage.


I like to call myself a pretty good mechanic, but I've got no clue what to do with this issue. The juttery electrics have already messed up 1 wiper motor, the PDC, aswell as my mental stability. Im going to start unplugging modules and accessoires such as an aftermarket headunit, to see if that solves it. If anyone has any clues, please let me know!

Thanks!