This is an all too common complaint coming into our shops. Starting up cold in the morning, the engine runs terrible and starts running better and better the warmer it gets. More than likely you have some stiction going on in the injectors but let's go over a few things here before we condemn the injectors.
Things to check:
Base Fuel Pressure
Let's start by saying you should change your fuel filter probably twice as often as you currently do. Ford recommends every 15k miles and we agree. If you pull out the upper fuel filter and see anything darker than the warm sandy beaches of Hawaii, you went too long. I think I need a vacation. Moving on. Base fuel pressure should be anywhere from 45-70 psi. The more the better. We set our adjustable regulators to 70 psi. Most blue spring kits run close to 70 psi. Once you have verified base fuel pressure next test injection pressure.
Injection Control Pressure
The 6.0L needs 450 psi of Injection Control Pressure (ICP) to start firing the injectors. The computer will not even send the signal if pressure is too low. The easiest way to test this is with a scan tool. Most generic scanners or apps such as Torque with an OBD communication device will be able to monitor this. ICP pressure should start at zero or close to and build quickly, 2-3 revolutions, to the desired 450 psi. Once running ICP pressure will vary depending on driver demand controlled by the Injection Pressure Regulator Valve (IPR). At idle pressure should be around 750 psi. If you are close and no varying wildly more than 50 psi, you're probably okay.
FICM Voltage
FICM Voltage is for real. 48V will make you remember its name. You can monitor this with a scan tool. The PCM will set codes if voltage is lower or higher than expected. Common codes are P0611 Voltage too low, P1378 FICM Supply Voltage High, P1379 FICM Supply Voltage Low. We recommend testing MPWR Voltage under a loaded condition and see if voltage drops. If so you have a weak FICM and need to rebuild it or get a remanufactured unit. Look for a new FICM Here.
Three important PIDS are
Base Engine Concerns
Let's hope you don't have a base engine concern but there are a few simple ways to inspect for engine damage.
First and easiest is to warm the engine and remove the oil filler cap. If you see a bunch of crankcase vapors and/or oil coming out you probably have a problem. This is a poor man's version of the Magnehelic Pressure gauge test. Here is an example of what you do NOT want.
Typically, if you have an engine concern the engine will not crank evenly. Disabling the fuel system or pulling the FICM relay and manually engaging the starter should let you crank the engine without starting it.
In a more professional setting performing a Cylinder Power Balance test, Relative Compression and Mechanical Compression Test would be necessary to condemn and engine. Consult your mechanic before trying this yourself. Mechanical compression can exceed 400psi.
If all of these check out, you need a set of injectors. Find those Here
You can always try some REV-X or Hotshots, that should buy you some time if you can't do the repair just yet.
As always, we hope this information helped you in some way and should you have any questions feel free to email us at sales@norcaldieselperformance.com or give us a call 888-290-3820.
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