@schnips you need to have it scanned. If you can get it running, drive to Advance or Autozone and have them do it for free. Start a new Post.
Whenever the engine won’t start you should first determine if the ignition system is getting spark to the plugs. As a simple and fast test I like to use a small amount of some starter fluid sprayed into the intake to see if that lets the engine fire up. If it does you have determined that there is a fuel delivery problem if the engine won’t keep running. If you don’t get any reaction from the engine after determining that the ignition and fuel delivery systems are okay then it is time to check the compression. There could be a broken timing belt possibly and a compression test will show that.
It sounds like EricD’s problem has to do with an intermittent power problem in the ignition area. Possibly to the ECU since the data port isn’t working. I suspect it is external to the ECU and proper testing for power to the ECU would tell the story. Hopefully the car will keep running until they can be rid of it but I sure would be leery of being stranded somewhere when the problem comes back again.
“The fuel pump sounds like it’s working”
Unfortunately, that’s not good enough
You shouldn’t guess about these things
Hook up a fuel pressure gauge and tell us what you have
To rule out a base engine problem, it would be a good idea to perform a compression test also
I agree with @knfenimore . . . have any codes pulled and report back
I second the idea about starting a new thread
My Father-in-law insisted on installing a crank sensor and, oddly enough, it remained problem free until Sunday night (11/10/13) when it refused to start after having some fuel put in the tank. The only thing that seems to work, and this very well may be voo-doo/magical thinking, is that if it doesn’t catch on the first or second attempt I have her wait 5-10 minutes and try again. That seems to been working…
With the new computer there is a code for an EDR valve issue, though I haven’t investigated the possible ramifications. I’m pretty much crossing my fingers and waiting for January.
Crossing fingers doesn’t work very well for these kind of issues. By following my previous instructions you should be able to figure out where the trouble is at. It sounds like you have an intermittent problem within the ignition system.
Maybe a used computer won’t work but where is the choice? If there is no communication with the computer and no wiring harness problem then the car needs a new computer or you could, at 240,000 miles, just replace the Corolla unit.
At that mileage if a car quits I recommend a one way tow. The computer and cat are shot and the rest of it is wearing a blindfold.
It is most likely going to be a waste of time and money replacing a suspected bad ECU before checking all the power inputs to it and making sure they are good first. Especially one that has a communications link problem.
The ECU’s edge connector contacts can get oxidized over the years. Some of those signals on the connector carry considerable current as they control relays and selenoids, so any increase in resistance could cause a problem. Not all can be cleaned. The connectors come in different pin styles. If the contact pins sort of look like a row of little copper colored fingers flush with the surface of the circuit board, these are fairly simple to clean. With this type, lightly rubbing a pencil eraser on them to clean them can sometimes prove to be a simple remedy.
Looseness, fraying, or corrosion where the ECU is grounded to the chassis is another source of ECU problems.