[reedspowerstroke]

My truck has been acting strange for a while now, and then the other day while driving the SES light came on and it began running like an old 2 cylinder tractor. I thought I blew the engine. But after I shut it off and restarted. it ran fine for a couple days then done the same thing again. I ran a scan and came up with the following codes;

P1316-Ignition Diagnostic Monitor Codes Detected
P0267-Injector Circuit Low Cylinder 3
P0470-Exhaust Back Pressure Sensor Circuit Malfunction
P0476-Exhaust Pressure Control Valve Performance
P0284-Cylinder 8 Contribution or Balance Fault

I have no idea what these mean, or where I should start. I could really use any help I could get.

 

[klhansen]

The critical codes in your list: P1316, P0267, P0284 have to do with the injector operation. Most likely what has happened is the latch on one of the UVC (Under Valve Cover) harnesses has come loose, allowing the connector to move enough to interrupt the injector circuit. It's a pretty common issue with the 7.3L. You should pull the valve covers off and check the harness connections to the VC gasket. You may want to just get new harnesses, which have improved latches on them, and replace both of them. They're about $25-$30 from International. Part #1830844C93

The other two, P0470 and P0476 mean you have a problem with your Exhaust Backpressure system, possibly the EBP sensor is bad or the tube to it from the exhaust manifold is plugged with soot. Those aren't killer codes, so I'd deal with the injector codes first.

 

[reedspowerstroke]

I was given a test to do to check the UVC harness, and to determine if it was unplugged inside. It was as follows;

Unplug the inboard 9 pin flat connector that plugs into each valve cover gasket.
Test the pins that go into the gasket. The front two pins, and the last two pins are the glow plugs. They should test less than 2 ohms when tested against a ground.
The 3rd, 4th, 6th, and 7th pins are for the injectors, and should test less than 5 ohms when tested against the center, or 5th, pin.

I did this test and found that all the glow plugs tested less than 1 ohm, and the injectors tested 3.3-3.6 ohms.

So, first of all, is this a valid test to determine if the UVC harness is coming off? And if so, then what else could be causing my problems?