Rough starting diesel
There are quite a few causes for a rough start. Please write back with as much detailed information as you can provide. What have you checked, found, tested, and replaced so far? Explain the vehicles maintenance history, is the engine light on and if so, can you provide me with the codes. I think it will be useful to share some items to check, to narrow down your search. I'm being honest with you so its not personal. The 6.0L is not a great engine. The legendary "Powerstroke" engine ended with the 7.3 The reason is due to the engine design change. The EGR system is a big problem and the injectors are not as strong and fail (break) sooner than they should. As always oil Level, Oil condition, and Oil pressure is very important. So first check the oil and see if it needs to be changed. While you are in there. Make sure that it hasn't been more than one year since the fuel filter has been changed. A clogged fuel filter or weak fuel pressure will force the injectors to work at higher pressures. the higher oil pressure will cause the injectors to wear out or fail sooner. After you check that out, you can move into more technical diagnostics. A compression test is the best way to confirm that your engine is fine. A bad ring or valve will cause a hard start and a rough idle. An external or internal oil leak will cause a rough start as well and there are several points in which these engines will leak. For example: at the ICP sensor, Injection pump and related high pressure hoses (check for leaks), internally, (underneath the valve cover) is a high pressure oil manifold. This manifold channels the oil from the high pressure pump and distributes it to the four injector in that bank. So there are five things that can leak here. Inspect the manifold for cracks, remove both regulator rods and inspect for broken O-rings(there are two and both are identified by screwing in flush with the face of the manifold), and the injectors themselves. The injectors can fail three ways. They will break in half, they will wear out and not pump fuel correctly, or they can lose an O-ring. You may want to inspect the EGR valve. If the valve is gummed up with carbon and is seized or moving too slow, the engine will run rough. If too much exhaust is allowed to be re burned then you will have a rough or hard start and a rough idle. The idle may improve as the engine warms up but don't jump the gun, testing is important. After that it get more technical. If there is an electrical failure than a professional scan-tool is needed to look at live data and to test components. Bad or loose wiring and plugs could be to blame. Also The injector driver module is a common failure for these trucks as well. With a scan-tool you can look at voltage going in and coming out. The voltage going in should be what the alternator is charging at (normal charging is 14 volts). The voltage coming out is 48 volts. if the voltage is less than that than you need a new injector driver module (no ifs, ands, or buts). There is a lot going on under that hood. I would like to help you solve your "Rough Start" problem but it will take time. Please write back with any questions. Be specific and try to ask every thing at once, to help speed things up for you. Good luck.
