Ford 6.4L Powerstroke Difficult Cold Start

Ford 6.4L Powerstroke Difficult Cold Start

The Ford 6.4L Powerstroke is a strong engine known for heavy-duty performance. Yet, in frigid winter temperatures, it also has a reputation for cold-start issues.

The team at Hot Shot’s Secret has developed this guide to walk with you step by step in diagnosing and troubleshooting your cold start issues. 

Glow Plugs

Glow plugs are an essential tool for starting diesel engines in cold temperatures. Diesel fuel needs aid during combustion, so glow plugs preheat the combustion chamber to atomize the fuel. If any glow plugs are faulty, starting your engine can be very difficult in winter weather. 


One common sign of a faulty glow plug is misfiring. Rough idling and white smoke are other signs that can let you know if your glow plugs have burned out or become damaged. 


Testing your glow plug system before the winter is straightforward. First, find each glow plug connection on the engine bank, unplug it and measure its ohms with your multimeter. If you receive readings between 0 to 1 ohm, you know the glow plug is working.


The cold start injector is one of the most important tools for ensuring your engine comes to a reliable start in winter. The Ford Powerstroke engine has a hydraulically actuated, electronically controlled unit injector (HEUI) system that’s often complex to maintain. 


A hard start with smoke during cold weather often indicates a faulty injector. It’s also common to see a dip in miles per gallon or a drop in engine performance and acceleration. The engine could even stall or misfire when the injector leaks and mixes with fuel. 


The main way to repair a cold start injector is to replace the part. You’ll need to locate the cold start valves, disconnect the electrical connector, disconnect the fuel line, loosen the new valve, replace the valve and reconnect the fuel line. 

Poor Fuel Quality

The HEUI system depends on engine oil for the fuel injector, so your oil’s quality is essential for cold starts. 


Lower-end engine oils in the 15W-40 range are thick like caramel, so freezing temperatures cause them to move even more slowly. 


Choose thinner engine oils like 5W-50 for better flow in frigid temperatures. This oil change will help the tight tolerance of the injectors in your Powerstroke and have similar efficiency as 15W-40 once the engine reaches a typical operating temperature. 

Solve Hard Cold Starts With Hot Shot’s Secret

Hot Shot’s Secret has an inventory of performance products to enhance a 6.4 Powerstroke that runs rough only on a cold start. Connect with our team now to ask a question, and let us help you find the perfect solution to take your engine to the next level. 

The contents of, such as text, graphics, images, and other material contained on the Diagnose Your Diesel section are for informational purposes only. Always seek the advice of your mechanic or other qualified professional with any questions you may have regarding your vehicle’s condition.