Im lost! Need other diesel head opinions

The 80 ml per minute is an invalid number for injector return flow, redo the injector return flow test with the correct procedures as a start.

What are your cylinder contribution readings? What is the rpm drop for each cylinder that looks off? What are the CP-3 return flow values?What ranges of load did you log demanded vs actual of rail pressure?

Exactly WHAT were the injectors that you replaced? New Bosch? Remans? Internet junk?

Based on your description 2 things come to mind; injector hanging open adn the charge is still firing as the exhaust valve opens, or, you have a valve dropped. Did you pull the VC, check lash and rocker position?

 

The typical return flow is 180 ml is 30 SECONDS at 20k psi and 1200 rpm, 80 ml in 1 minute is invalid because it is way out of the expected range.

Return flow is not going to tell you if the injector is malfunctioning, it just indicates that the return flow circuit is not worn out. An injector that is hanging or working incorrectly will exhibit other symptoms and still have good return flow. Simply cannot base the diagnosis on just one test, you have to run thru the others to get a more complete picture. If there is a malfunctioning injector it may show on a contribution and kill test, IF the problem occurs at an idle.

The valve seats will get loose in the head and float, really hard to diagnose that condition because it is intermittent. The knock you are describing is more than likely an injector hanging. If this is happening at an idle you should see that on contribution\kill test.

Does not matter if you bought remans from an authorized dealer, they can and wills till be bad. I have replaced more remans from Bosch than anything else, they are just not a good choice for replacements unless you monitor constantly.

 

Yeah, as a guess you have some injectors that are not working as they should in off idle operations. They should show some variations in contribution if it is a mechanical issue but not a given.

Here is the latest injector return info I have. It is possible this has been updated but at the rate FCA is pulling all the testing protocols from their software not even sure this is good anymore. They seem to want to basically hamstring the techs form doing anything meaningful and dump all the decisions back to their resolution center for directions. They say less than 160 ml in 30 seconds is good but do not say what is expected, what I have seen is generally 160-180 ml on known good injectors. Still have to apply some logic to this stuff, this CR diagnosis stuff doesn't always follow logic closely.

INJECTOR RETURN FLOW TEST @ 1200 RPM AND 1400 BAR RAIL PRESSURE
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1. Operate the engine until the coolant temperature is above 82.2°C (180°F).
2. Turn the engine off.
3. Remove the banjo connector from the fuel drain tube at the rear of the fuel filter housing.
4. Install fuel system test fitting 9012 in place of the banjo connector.


NOTE: Do not use test fitting 9014 . This fitting will block return flow from the High Pressure Delivery Pump and damage the seal and could potentially damage the engine.
5. Install a 5/16 diameter rubber fuel hose (Hose A) onto the test fitting and into a fuel container.

NOTE: This hose is used to measure the High Pressure Pump return flow.
6. Remove the vehicle fuel return line (Quick connect) from the engine fuel drain tube.
7. Install a 5/16 diameter rubber fuel hose (Hose B) onto the engine fuel drain tube and into the fuel container.

NOTE: This hose will be used to measure the Injector return flow for this procedure.
8. Start engine and allow to idle for 30 seconds. This step allows the flows to stabilize.
9. Using the scan tool, navigate to ECM view -> PCM Cummins -> More Options-> System Tests -> Fuel Pressure Override Test. Select Start, then press Next.

NOTE: While the test is running, record the FCA duty cycle % and actual rail pressure. Record the readings on the Cummins Diesel Diagnostic Worksheet located under e-files, service, Star center in Dealerconnect.
10. Press the Run button to start the Fuel Pressure Override Test. The engine speed will elevate rapidly to 1200 RPM and the rail pressure will increase to 20000 psi (1400 bar). At this point, move (Hose B) from the bucket and insert it into a graduated cylinder.Collect the fuel until the Fuel Pressure Override Test times out (30 seconds).
11. Measure and record the amount of fuel collected in the graduated cylinder.

NOTE: Flow should be less than 160 ml for 30 seconds.

NOTE: If the amount of fuel collected is greater than 240 ml/30 secs, it is recommended that all 6 injectors be replaced.
12. If the flow is less than 160 ml/30 seconds, the test has successfully passed. If the flow is greater than 160 ml/30 seconds, but less than 240 ml/30 secs, turn off the engine and remove all 6 high pressure fuel lines. Re-torque the high-pressure connector nut for each injector. Inspect for damage, repair/replace as necessary. Reinstall the high pressure fuel lines. Re-measure the injector return flow using steps 8 through 12 as a guide. Continue on to next step.
13. If the amount of fuel is still greater than 160 ml/30 seconds after re-torquing the high-pressure connector nuts, turn the engine off and remove the #1 high pressure fuel line. Cap the #1 fuel port using tool 9864 for the 6.7L engine on the fuel rail and re-measure the injector return flow using steps 8 through 12 as a guide. Repeat this procedure for injectors 2-6. Continue on to next step.
14. Replace the fuel injector and High pressure connector of the injector that shows the largest amount of change when capped off.