My 04 Expedition has recently been hard to start and when driving I get a loss of power for about two seconds. RPMs go down to almost nothing, then the engine kicks in again and it goes up to 3,000. The battery light turns on for a few seconds then off.

i have no codes. I have a new battery and I have tested the alternator, but I haven't been able to test it when the car loses power.

i have changed the fuel pump, fuel filter, spark plugs, air filter, and boots. I have cleaned the throttle body.

Any ideas as to what this could be? I've done a visual inspection of the fuse box by disassembling and then reassembling. I've inspected my battery cables but they see fine. Could this be the ECM? Perhaps a sensor is going?

 

Is your foot still pressing on the pedal when this happens or does it race on its own?

My first guess would be to start at the ignition switch. But the other guys will be more help to you than me.

 

It will still do this even if my foot isn't on the ignition.

 

But you're traveling at the same time?
From what you describe it sounds like the same thing would happen if you were turn off your key and then turn it back on again while you're driving -- that's why I suspect the ignition.

Also, double check those wires under the hood from the battery. You might've missed something rubbing/chaffing on the harness.

 

I've had 2 alternators fail in my '01 Expedition, and it's very similar to what you describe... I'm trying to remember, however, if the engine kept running either time.

In my case, I know that the instrument cluster went goofy the first time, as if it had lost the serp belt... I know I was able to get it restarted, and drive it home - and it didn't act up again for a while. I don't remember if I tested the alternator at that time.

Have you tried testing your alternator with a multimeter, to see what kind of voltage it's putting out? I think that's how I confirmed my first failed alternator, but I can't honestly remember.

 

The battery light coming on is simply because the engine RPMs drop. The problem to solve is the engine cut out issue and then the battery light issue will take care of itself. That being said, I'd replace the crankshaft position sensor.