My 2003 4wd Ranger 4.0 automatic 225K miles is doing something very odd. Shortly after startup and drive away, perhaps a quarter mile, I lose power momentarily and get a flashing "check engine" light. In ten or fifteen seconds, the power is back, flashing check engine light goes away in less than a minute and no problems for the rest of the day even if the truck sits for many hours. Next day, same thing however. Never seen anything like it. No code is pulled when checked with code reader.

Any ideas?

 

Welcome to the forum

The flashing CEL means engine is misfiring, and to back off the gas pedal, just FYI
If often won't set a code

Could be a few things
ECT(engine coolant temp) sensor, this is a 5volt sensor only used by the computer, it is used for a few things, one is to set Choke Mode, cold gasoline engines still need to be choked, which means Rich fuel mix and high idle until they warm up
Could be there's a temp that the ECT sensor gets to and its voltage jumps or drops, and then goes back to where it should be, not common but possible

If you were to get a Bluetooth OBD2 reader, $15-$25 then you could watch Live Data on your phone or tablet, and "see" what the computer sees from sensors
These Bluetooth readers work on ANY vehicle made from 1996 and up, its the Law
So not a Ford thing, if you plan on driving for a few years its worth the investment

Could be IAC Valve closing and then opening back up
Could be fuel pump shutting off then restarting

 

thanks! ordered the bluetooth gadget and it comes tomorrow. I'll advise what happens next. Rich

 

The little gadget came, I downloaded the app, but can't seem to make it work yet.

Further info: I started the Ranger first time yesterday morning and let it warm up in the driveway. It warmed perfectly and never displayed any symptom at all. I drove away after it reached normal operating temp, and it performed flawlessly all day. This morning, I started it up and only waited until the temp guage moved ever so slightly indicating the thermostat was opening. Drove away with no problem of any kind.

I will keep trying to get the Bluetooth gadget working.

 

What model bluetooth unit did you get?


As for the vehicle, could you have gotten some "bad" gas
All gasoline has some water in it, its from condensation in the storage tanks and transport trucks
"Bad" gas has more water in it, and, of course, water doesn't make you GO, lol, so stumbling and rough running can be a sign of "bad" gas

And water is heavier than gasoline, so if a vehicle sits all the water will settle to the bottom of the gas tank...............which is where the Fuel pump SUCKS the gasoline in, so you can get a big gulp of water at startup

Ethanol can be used to get rid of the water in a gas tank, ethanol will bond with water so it can be passed thru the engine without the stumbling, slightly less power but no stumbling
Octane boost or gas line antifreeze is just small bottle of ethanol that can be added to get rid of the water

Regular gasoline usually has 5-10% ethanol so good to use if you think there is water in the tank