I found this explanation on how to identify which injector is bad. Hope this helps someone.
How do 6.0L Injectors Work?
The Powerstroke 6.0L injector is a HEUI Injector made by Siemens. HEUI stands for hydraulic electronic unit injection. A high pressure oil pump located at the back of the engine's valley area produces as much as 3,770 PSI. This pressure is used by the injector to generate the actual force which injects the fuel. Because the injector multiplies oil pressure by a ratio of 7:1, injection pressure can be over 26,000 pounds per square inch. Two 48-Volt 20-Amp solenoids control the position of a spool valve in the injector which routes high pressure oil into and out of the injector and ultimately controls when injection occurs. These injectors have a very fast response time and will actually perform several separate injection events for each power stroke for improved power and reduced engine noise. The injectors receive high pressure oil from a heavy duty rail located above the injectors, and receive fuel through cast passages in the cylinder heads.
What are some common symptoms of injector failure?
Typically when one injector fails, we find that the engine is hard to start and is low on power. If two injectors fail starting will be very hard or the engine will not start at all. If you do manage to start the engine, it will be very low on power.
Our experience is that when one injector fails, the rest are not far behind. From a time and labor standpoint it usually makes sense to replace the injectors as a set!
What causes 6.0L Injector Failure?
Besides design issues, the #1 cause of 6.0L injector failure is poor maintenance! Because engine oil at very high pressure is used to operate the injectors, keeping the oil clean is absolutely essential to maximum injector life. Extended oil change intervals are deadly to 6.0L fuel injectors - unless you are running a good bypass filtration system. We highly recommend the FS-2500 bypass oil filtration system (which we also sell) if you are intent on extending the life of your injectors.
Besides keeping the oil clean, fuel is the next major issue that affects 6.0L injectors. Poor quality fuel with water or dirt in it is absolutely deadly to your injectors. Also, because the fuel actually provides a cushion for the internal valving of the injector, anything that causes low fuel pressure will kill the injectors. This includes not observing proper fuel filter maintenance. We recommend that fuel filters be serviced at 15,000 mile intervals. Low pressure caused by a failing fuel pump can cause repeat injector failure. ALWAYS check fuel pressure after installing new injectors. Use manufacturer's spec for your truck, but generally look for around 65-70 PSI with the engine running. Finally, running a 6.0L Powerstroke out of fuel is deadly to injectors! On early trucks, if you run out of fuel, you will usually be buying 8 injectors. If you think you are going to run out of fuel, stop, shut the truck off, and walk. It may save you $2,500. Later trucks have a PCM strategy which limits pressure to prevent injector damage during a low fuel condition, but it is still a situation to be avoided at all costs.
Tips for diagnosing faulty 6.0L Fuel injectors:
Please note that we cannot begin to cover all the diagnostic strategies and possible failures of the 6.0L fuel injectors here. These are just some useful tips we have found. The starting point is always performing a cylinder balance test using the Ford IDS / WDS or equivalent scan tool. This allows you to visually see which cylinders are not contributing.
Other Diagnostic Tips:
- Any time you suspect an injector issue, check fuel pressure. Correct fuel pressure is vital to proper engine operation.
- Combustion gas (air) entering the injector and fuel rail is a common problem and will cause a random misfire not only on the cylinder the problem originated on, but on other cylinders as well once air enters into the fuel rail. There are two possible routes that air can enter through the injector. The first is through a worn/damaged needle and seat in the injector, the second is through a damaged copper washer at the bottom of the injector. Follow the following steps to find which cylinder is causing the problem:
- Remove fuel pump and fuel injection control module relays
- Remove the fuel lines that run from the fuel filter housing to each cylinder head.
- Put a balloon over the end of each of the fuel lines coming from the head and use a rubber band or zip tie to seal the balloon tightly to the line
- Have someone crank the engine and watch the balloons closely for any sign of pulsing which indicates compression gas is being forced through the injector. This will allow you to determine which bank the problem is on.
- Remove all but one glow plug from the bank with the problem. (Removing the glow plugs relieves compression in the cylinder.) Crank the engine and move the glow plug from cylinder to cylinder to find which injectors have a problem.
- Remove affected injectors, and look carefully at the copper gasket at the tip. The washer should display an even circular crush pattern. If in doubt, replace the washer and try again. Beware of missing washers, or possible installation of two washers.
- While injectors are removed, you can also use a hand vacuum pump to do a quick test for a damaged injector tip needle/seat. Locate a piece of rubber hose that fits tightly over the end of the injector tip and push it on. Connect the opposite end of the hose to the pump and apply vacuum. If the injector will not hold a vacuum, it must be replaced.
- Typically copper washer leaks will cause the balloons to fill up quickly, while internal injector leaks will only cause slight pulsing of the balloons.
- Before beginning any diagnosis or parts replacement, always determine if your truck's PCM and IDM (Injector Drive Module) have been updated to the latest software. Recent changes correct hard cold start/cold smoke/poor cold running issues by energizing the injector coils during glow plug operation in order to heat the oil in the injectors. Software is VERY important to 6.0L operation.
- If oil is very dirty, change it and see if operation improves.
- The 6.0L has many issues with electrical harnesses rubbing through - even the updated harnesses. The injector harnesses can rub through near the valve covers and either prevent an injector from firing or cause it to stay on all the time.
- Any time a 6.0L develops a stalling or a miss, check the problem out right away to prevent possible further damage!
How do I know which injectors to order?
- 6.0L injector replacement is not extremely difficult and does not usually require special tools, but is only recommended for those with at least a minimum of mechanical training.
- EVERY time an injector is removed / replaced the copper tip washer and o-rings MUST be replaced. Do NOT install two copper washers (Be sure the old one did not stay in the head.)
- Replacement time can vary from a few hours for a pickup to ??? for some van conversions.
- Consider replacing the seals on the high pressure oil rail while the valve covers are off - leaks here can cause hard hot starting.
- Torque on the injector retaining bolt is very critical! Earlier trucks require 24 ft-lbs, and later trucks, 26ft-lbs. Look it up for your truck!
- "Quick" Removal /Installation Guide (NOT a substitute for your manual):
- Remove valve cover
- Remove 8 bolts that hold high pressure oil rail to rocker arm cover and pull straight up to remove. A special tool to disconnect the feed line from the rail allows you to remove the rail completely which is convenient.
- After disconnecting the electrical connector, use a 19mm 12 point chrome socket to push the remaining portion of the connector body out of the rocker housing.
- Loosen the torx bolt that holds the injector in place. This will unseat the injector - do not use air tools, and do not pry on the injector coils which will damage them. Also, be sure the copper tip washer does not stay in the head.
- Reverse to install - be sure to lubricate all o-rings with engine oil before installation, and remember that injector hold down bolt torque is very critical. Seat high pressure oil rail by hand before tightening bolts.
- Upon starting the engine, it will run rough for a long time, until all the air gets out of the system.
- The safest way to determine if you have early injectors or late injectors is to remove a valve cover and look at the injectors. Take a look at the picture at the top of the page and notice the difference in the color of the wire carrier that routes the wires to the solenoids. The early carrier is white, the late carrier is black.
- You can also determine application by part number - see below:
- Early Injectors: (White Top)
- Ford Part Number: 3C3Z-9E527-AE
- Fits 2002.5 - 2003 Ford Powerstroke 6.0L
- International Part Numbers: 1843089C91, 1845879C91, 1843481C94, 1843481C95
- Fits 2003 - 2004 International VT365 6.0L
- Late Injectors: (Black Top)
- Ford Part Number: 4C3Z-9E527-AA
- Fits 2004 - 2006 Ford Powerstroke 6.0L
- International Part Numbers: 1844751C2, 1846692C92
- Fits 2004 - 2006 International VT365 6.0L and VT275 4.5L