How to Test and Replace Faulty 6.7L Powerstroke Diesel Injectors

How Do the Injectors Work on the 6.7L Powerstroke Diesel Engine?

The 6.7L Powerstroke turbo diesel engine used in Ford Super Duty trucks from 2011-2019 utilizes a high pressure common rail fuel injection system with six hole injector nozzles. This allows for precise control of both injection pressure and timing in order to maximize power and efficiency.

High Pressure Common Rail Fuel Delivery System

At the heart of the system is a high pressure fuel pump driven by the camshaft. It draws fuel from the tank and sends it to the common rail at pressures over 30,000 psi. The rail acts as a accumulator to dampen pressure fluctuations and ensure consistent delivery to each injector.

Attached to the common rail is the set of six piezo-electric controlled injectors. As their name implies, applying voltage to the piezo crystals causes them to rapidly change shape and allow the injector to open or close.

Precision Control Over Injection Events

This fast acting system allows the engine computer to precisely time up to six separate injection events per combustion cycle. Small pilot injections before the main event help control noise by gradually building cylinder pressure. The ability to adjust timing and quantity allows optimization of power, fuel economy, and emissions.

Redundant Low Pressure System

While the high pressure side handles actual injection, a separate low pressure system feeds and bleeds off fuel to cool and lubricate the injectors. This prevents premature wear and helps stabilize injector operating temperatures.

How to Test 6.7L Powerstroke Injectors

If you suspect issues with one or more fuel injectors on your 6.7L Powerstroke diesel, here is how you can test their operation:

Check for Diagnostic Codes

As with most engine issues these days, your first stop should be scanning for diagnostic trouble codes (DTCs). Since the engine computer closely controls and monitors injection system components, a sensor or injector fault will often set a code. Know what the code means before just replacing parts.

Listen for Abnormal Noise

An experienced technician can diagnose a lot by ear. Use a stethoscope or long screwdriver as an improvised listening tool. Place the tip on different areas of the engine while cranking and running. Compare sound from injectors on multiple cylinders.

Ticking or rattling noises point to a problem. All should make a characteristic clicking sound at idle from their rapid pulsing action. Note any cylinders lacking noise or making loud knocking instead.

Perform a Buzz Test

This simple test confirms basic injector coil windings operation prior to cranking the engine. Disconnect both battery cables to disable power. Reconnect only the positive cable. Listen next to each injector connector plug while toggling the key.

A properly working solenoid and coil will emit a buzzing sound when 12 volts are applied. If one or multiple injectors fail to buzz, there is likely an electrical fault or bad winding.

Monitor Balance Rates

Imbalances in fuel from injector to injector will hamper performance. This often results from dirty nozzles or failed components. Connect a diagnostic scan tool to read balance rates.

At idle with a warmed up engine they should generally be less than 3% deviation from cylinder to cylinder. Try cleaning injectors first if higher. Still bad? Further individual testing is needed.

When to Consider Replacing Them

Before throwing expensive new injectors at a rough running or poorly performing 6.7L Powerstroke, first try cleaning techniques. Consider replacement if they fail testing or continue to exhibit faults such as:

Visible Damage or Leaking

Carefully inspect removed injectors for any visible damage to the body, electrical connector, or nozzle tips. Also check for any signs of fuel leaks around the injector body once installed - leak testing kits make this easier.

Clogged Nozzles

Even with fuel filters doing their job, gunk, varnish, and carbon buildup prevent proper fuel atomization. Try cleaning kits first, but clogs bad enough will require new nozzles or entire injector.

Failure of Coil Windings

Electrical faults in windings or wiring prevent proper injector pulsing operation. Confirm with buzz or balance testing first. Replacement needed if cleaning contacts and connectors doesn't fix.

While complex, the common rail fuel injection system of the 6.7L Powerstroke gives incredible performance. But it does require maintenance, occasional testing, and replacement of wear items like injectors over very high mileage use.

FAQs

What are some common symptoms of bad 6.7L Powerstroke injectors?

Common symptoms include rough idle, misfires, loss of power, increased exhaust smoke, and fuel odor from leaking injectors. The engine computer may also set diagnostic trouble codes related to injection performance or cylinder misfires if it detects issues.

Should I replace all injectors at once?

It's generally recommended to replace all injectors as a set once the engine has very high mileage. However, during testing you may find only one or two faulty ones. Just make sure flow rates and operating characteristics match across all cylinders.

Is cleaning 6.7L Powerstroke injectors a viable fix?

Injector cleaning kits can effectively remove buildup and restore proper fuel flow in lightly clogged nozzles. But they can't fix electrical or mechanical damage. Clean first as a diagnostic before exploring replacement.

What causes injectors to fail prematurely?

Frequent short trips and cold starts can lead to early carbon buildup and clogging issues. Maintaining clean diesel fuel, filters, and oil is key. Using high quality fuels and additives also helps minimize deposits.