View Full Version : E39 540IA - Dead on the highway - Major Boum

05-01-2006, 07:46 AM

Our 1997 540Ia is playing a hard game with us, especially on highway. When we cruise at highway speed, 60mph and up, the car can randomly die for about 3-4 seconds and instanly come back to life righ after. When I say "dead", it feels like if you were turning the ignition to off, rpm shows "zero". Once the car goes back to life, it make a big boum, sort of backfire and everything is back to normal... This can happen as much as 2 time during a 30 minutes trip ....

What can that be ?

05-01-2006, 08:50 AM
It's an electrical problem. With it going completley dead it might me the ignition or the computer. I had the same problem with my 84 e30.
Driving along and she shuts of, after a few seconds comes back to life.
Replaced the computer and the problem never came back. Having said that I'm not saying thats the prolem with your car. However I'm sure it's electrical not mechanical.
You would need to take it in.

05-01-2006, 03:49 PM
Hey mz3bo,

any codes???

CPS (cam position sensor) comes to mind as an intermitant electrical problem and relatively easy to fix...

MAF (mass air flow sensor) or oxygen sensor,

or even loose battery terminals.

Have the codes read...