Hi forum. 210k miles on original injectors with stock, 10 micron fuel filtration. My symptoms have been occasional rough idling as if running on 5 cylinders and occasional slightly longer starting than normal usually accompanied by a small puff of smoke. Usually clears itself with heavier loading or some spirited driving. I’ve used injector cleaners on occasion for periods as long as a couple months, but I couldn’t discern a significant difference.
I’ve explored this same subject in the past and have even posted on this forum about it. Some very knowledgeable people replied saying that based on mileage at the time and the use of only stock fuel filtration ( 10 micron ), that it was very likely worn injectors with less effective sealing ( resulting in leakage ) and less effective spray pattern, etc.
Given how the engine still seems to run well other than occasional hiccups above and what others have said about how long they’ve been able to run on original setups I’m interested in first being able to confirm problematic injectors. The scientist in me wants to measure a problem...
Towards that end I’m reviewing the limited ways to test the injectors while in the truck and hoping others can share their experience and comment on my thoughts...
-The cylinder contribution test ( based on measuring duty cycle of injection ?) is supposedly unreliable with immediate subsequent tests having varied results ? Can it be repeated enough times to actually learn something about condition of injectors or are there variations on this test that do reveal the condition of injectors ?
-The injector kill test is a good way to verify that an injector is working poorly or not at all, but seems to tell relatively little about injectors that perform moderately well or better ? It would seem a good test to perform when I have my intermittent 5 cylinder symptoms to isolate which injector(s) is problematic.
-I’d seen somewhere about measuring injector performance based on crankshaft speed and thinking about using my oscilloscope to measure crankshaft speed ( CKP ) and then performing some spreadsheet calculations on the results, but I’ve now read that this ECM (CM848) will compensate duty cycle to regulate engine speed so it seems this wouldn’t be a reliable way to test ? I suppose rather than comparing crankshaft speed of each injection ( using the fastest injector crankshaft speed as a reference ) perhaps one could compare crankshaft speed against duty cycle ( positive % ) to determine how effective injector pulse is ? I suspect somebody here knows more about this.
-In the end I come back to the Mastertech video series that came out when the 3rd gen. trucks were released ( linked below ). Being a shared low-pressure injector return ( without individual injector returns ) it seems this test requires capping off individual injectors and measuring the shared return fuel flow to see if the capped off injector brings fuel amount within specification or for comparing return amounts of each injector ? Of course, this is only about leakage ( leak-off ) and says nothing about other injector performance like spray pattern.
*As a side note this post reminds me of a free “Leak-off testing of solenoid diesel injectors” technical video that I watched at https://www.ourvirtualacademy.com/. They offer a free 14 day trial with 3 free videos including this video which was amazing for me for the hydraulics behind fuel injector operation, understanding injector mechanics in general, potential problems with injectors particularly with contamination. There are some good high magnification photos of contamination. I have nothing to do with website.
*Mastertech video mentioned above:
Thank you, Sven
I’ve explored this same subject in the past and have even posted on this forum about it. Some very knowledgeable people replied saying that based on mileage at the time and the use of only stock fuel filtration ( 10 micron ), that it was very likely worn injectors with less effective sealing ( resulting in leakage ) and less effective spray pattern, etc.
Given how the engine still seems to run well other than occasional hiccups above and what others have said about how long they’ve been able to run on original setups I’m interested in first being able to confirm problematic injectors. The scientist in me wants to measure a problem...
Towards that end I’m reviewing the limited ways to test the injectors while in the truck and hoping others can share their experience and comment on my thoughts...
-The cylinder contribution test ( based on measuring duty cycle of injection ?) is supposedly unreliable with immediate subsequent tests having varied results ? Can it be repeated enough times to actually learn something about condition of injectors or are there variations on this test that do reveal the condition of injectors ?
-The injector kill test is a good way to verify that an injector is working poorly or not at all, but seems to tell relatively little about injectors that perform moderately well or better ? It would seem a good test to perform when I have my intermittent 5 cylinder symptoms to isolate which injector(s) is problematic.
-I’d seen somewhere about measuring injector performance based on crankshaft speed and thinking about using my oscilloscope to measure crankshaft speed ( CKP ) and then performing some spreadsheet calculations on the results, but I’ve now read that this ECM (CM848) will compensate duty cycle to regulate engine speed so it seems this wouldn’t be a reliable way to test ? I suppose rather than comparing crankshaft speed of each injection ( using the fastest injector crankshaft speed as a reference ) perhaps one could compare crankshaft speed against duty cycle ( positive % ) to determine how effective injector pulse is ? I suspect somebody here knows more about this.
-In the end I come back to the Mastertech video series that came out when the 3rd gen. trucks were released ( linked below ). Being a shared low-pressure injector return ( without individual injector returns ) it seems this test requires capping off individual injectors and measuring the shared return fuel flow to see if the capped off injector brings fuel amount within specification or for comparing return amounts of each injector ? Of course, this is only about leakage ( leak-off ) and says nothing about other injector performance like spray pattern.
*As a side note this post reminds me of a free “Leak-off testing of solenoid diesel injectors” technical video that I watched at https://www.ourvirtualacademy.com/. They offer a free 14 day trial with 3 free videos including this video which was amazing for me for the hydraulics behind fuel injector operation, understanding injector mechanics in general, potential problems with injectors particularly with contamination. There are some good high magnification photos of contamination. I have nothing to do with website.
*Mastertech video mentioned above:
Thank you, Sven