I have a '96 E-350 with a 7.3 that ran great, then I parked it and it sat outside for 3 years. Went to start it and my Idm was bubbling, full of water. So I bought a used one off ebay now it starts but is only running on 5 or 6 cylinders. Did I get a bad Idm? Did a buzz test and they all buzz but some loud some quiter. I have codes p1262, p1266, p1278, and p0476. Thank you for the help!

 

Did the connector have water in it or any corrosion on the pins? Maybe injector wiring harness got chewed through. The buzz test sounds like your injectors aren't too happy. Did you at least drain the water from the pan or hopefully change the oil first? As I understand it the oil side of these injectors are pretty sensitive

 

Have you checked the engine harness to the injectors for the drivers side? P1262= High to low side short on cylinder #2. P1266 the same to Cylinder #6. I don't see a P1278, but P1268 is High to low ide short to cylinder #8. If the Van has sat for 3 years, some unwanted critters might have made a meal out of some of the wires. Also check the plugs to the valve cover for melted connectors or burned pins. The under valve cover harness could give these codes if they are bad also.

 

All I did was change the fuel filter, I didnt think to drain the oil pan but the oil isnt milky. The plug on the idm looked fine just water inside. I checked the wiring didnt see any problems. I have not pulled valve covers yet since it ran so good before I wouldnt think the wiring under them would go bad from sitting but maybe I should check them. I kinda thought maybe my used idm might be bad. Can an idm only fire 5 cylinders or is it all or nothing?

 

The IDM will shut one bank off if it detects a problem on a cylinder on that side, to protect itself. Do you have another 7.3 to test the new to you IDM? Or know someone that has one? Any year 7.3 will work, although the 94.5-97 will be easier to get to for the test. On the 99-02, The drivers side inner fender has to come out to access the IDM. Plug the new to you IDM into the test 7.3. If the miss follows the IDM, then it is probably bad.

 

6&8 being in common, I would be looking at that UVCH connector, and as said, ohm out all wires between the IDM and UVCHs, just for good measure.

Can you get it hot enough to do a CC test?