Engines dies after 2.0 minutes

[imbvl]

I recently bought an '01 X5, 4.4, auto tranny, 80K miles. When started from cold, the engine dies after 2.0 minutes (stopwatch). It restarts readily, and again dies after 2 minutes. On a 70-degree morning (south FL) it will die twice, on a 50-degree morning it will do it 3 - 4 times. Or if it sits during the day and cools down, it will do it again. Otherwise it runs fine.

I took it to the dealer. They replaced the Mass Air Flow sensor, and the Throttle Motor, and something else, but took them out when nothing changed. There had been a prior engine-compartment fire, and the engine wiring harness was suspect, so they changed that. No help. After a month, and $3100, the next step was to replace the ECU, without the opportunity to swap it back. $3100 and no improvement was over-the-top, so I took the truck back, and started looking at it myself. (I've lots of prior mechanical experience, on BMWs and others.) The Right Front wiring harness also looked suspect, lots of splices and wiring colors that didn't match the Bentley manual, so I replaced it. ($350 and LOTS of time.) No improvement. Does anyone know enough about the ECU programming, to suggest what signal it expects, otherwise it turns off the engine after 2 minutes, with a "Eng Fail Safe Prog" message in the LCD?

Also, I saw in Bentley that the electric fan in front of the radiator is powered up at 20% during start-up, and the voltage generated during spool-down is compared to some standard. Mine spins, but I don't know how long it should take to wind down. Does anyone out there? Replacing the fan assembly is rather expensive, if it's hit-or-miss.

Another (maybe relevant) observation: In the DME box, I noticed that two wires (0.50 black/yellow and 0.35 blue) had been stripped and wrapped/twisted together, by someone, some time. At one time that I started the engine during the weeks I've been working on it, I think that it ran longer than 2 minutes when those wires weren't connected, but I don't remember exactly. Another time it wouldn't start at all, when the wires weren't connected. Right now they're connected - it starts, but still has the stopping problem.

Any help on this would be GREATLY appreciated!

Bruce, in FL.

[lo_jack]

I suggest putting a scanner on the car, getting as much realtime data as you can for those 2 minutes, and comparing with someone else's stock running 4.4 to see if you can find where your fault is. If the wiring is suspect, you may not get a check engine light even if it is out of parameters, though you would think that if it refused to run, the ECU would throw a code as to why it believed it was not running.

Good luck, that does not sound like an easy diagnosis to make but it looks like the dealer is at least helping by not sticking you with the costs of the things that don't fix it. I don't know anyone that isn't a dealer that has tuning software for these cars.