Does your 7.3L Power Stroke Diesel feel like it’s only running on half the motor, or that it just doesn’t have the towing power it used to? After checking for codes you may find a code P1316, unfortunately this code is only telling you to check the IDM. As a diesel owner this is a scary thought….. is it an injector, the IDM failed, or even worse, multiple injectors? All of these scenarios sound costly and testing the IDM requires a professorial scan tool, that can run a “buzz test”
So, What is a Buzz Test??
This test is a sequence of duty cycles to activate the injectors. This gives the technician the ability to hear a audible tone of the injector pulsing. This ‘Buzz test’ helps identify if there are any faulty injectors or drivers.
With the 7.3L Power Stroke engine most often this problem is with the Under Valve Cover (UVC) Harness. This is where the wiring passes into the engine to deliver power to the injectors and glow plugs. What seems to be happening is that the natural vibration of the diesel engine is loosening the electrical connection. This gap in the harness connector pins either stops making the connection, or increases the resistance causing the amperage to increase resulting in a burnt up harness connector.
How do you test for this condition without a scan tool?
As the engine is starting, you maybe experiencing a hard start that is accompanied by a distinct sound….
Here is a audio clip of a 7.3L Power Stroke starting up with one UVC Harness not working.
Doing a temperature test on the exhaust manifold is another way of determining what cylinder(s) are not firing. This can be done several ways; one way would be to use a inferred temperature gun. What you are looking for is a temperature difference between the cylinders of the exhaust manifold. This can also be done by dripping VISINE® or equivalent eye drops on the exhaust manifold ports. When the manifold is cold the eye drops will cling to (stick to and run down) the exhaust manifold. As the engine warms up the eye drops will start to bounce off. A correctly firing cylinder will produce enough heat in less than a minute to make it completely bounce off with no trace of liquid on the exhaust manifold. With either test the side not firing will be very slow to heat up.
Once you have determined what side of the engine is the problem, it’s time to pull the valve cover off and inspect the harness connectors.
Tech Tip- On the drivers side valve cover, there is hidden bolt under the crank case vent. On the crank case vent, their are 2 o-rings that when removed will not be reusable do to oil saturation or swelling. DO NOT remove these two bolt holding the vent on, unless you plan on replacing these o-rings. Use a boxed-end wrench to brake free the bolt and continue to remove bolt using your fingers.
Ford has recognized this problem and has released a connector wedge to resolve the connector from loosening. Part number 2C3Z-14A163-AB