Re: Cold Start Issues
The first thing I would do is check the glow plugs and scan it. Sometimes the connector on the GPGM is burnt, it is on the right valve cover. But by far the most common problem for your hard start problem is stiction. Now this can be tuff to diagnose because no scanner can give you the data to diagnose it, the only way to diagnose stiction is with a Hickok G2 tester, I've used one and it works and will 100% diagnose a stiction problem.
So the fix, the only way to fix this stiction issue 100% is with a set of Motorcraft injectors, anything else is just a band-aid, I've tried them all and then tested the results with the Hickok G2, they can help but won't fix the Stiction isssue.
I've seen a truck like yours, won't start in 30-40*, replace the injectors with Motorcrafts and they will start in -15 without being plugged in. U-tube has video's on how that tester works.
I used to own a shop and have one of those testers, I've seen it used on 100's of trucks. So if you have it hooked up on a cold engine, (overnight cold soak) and started the engine, you would see some of the stiction start to disappear after the first minute of run time, some injectors would take longer, some would never clear up, that's why it's tuff to diagnose. You have less then a minute window to catch it 100%.
So if your glow plugs work correctly, your battery's and starter are good, then your problem on a 6.0 is stiction pure and simple.
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