Hello. This post concerns a recent repair I did on a customer's Detroit Series 60 DDEC V.
The truck came in with the check engine light on and a miss.
One of the other guys scanned it and found a dead miss in #1 cylinder, and an active code 61, FMI 0 for cylinders 1 and 3.
The code descriptor for this is the injector response time is too long, and using the Detroit diagnostic program I found the code for #3 became active when the engine was running, and that injector response time was about .63 seconds as opposed to a consistent .79 to .82 for the others. There was also an obvious miss while running.
The Mitchell information system gave very little diagnostic information for the code, other than saying it could be a wiring or injector problem. I didn't really need to waste time reading just for that information.
I figured I would start by checking harness continuity from each injector to the harness connector at the left rear of the engine. When I unplugged the connectors from the injectors I found each connector full of oil. I doubted whether that could be a problem; injector connectors on especially the pre-EGR DT466 always have oil in them whenever I work on one of those, but there was nothing to lose by finding out.
I blew the oil out of the injector connectors with shop air, then cleaned both the connectors and the pigtails up by spraying them with electrical contact cleaner.
After plugging the connectors back in, I started the engine and monitored it with the laptop.
The miss was now gone and all injector response times very close on all cylinders. The injector codes didn't come back after being cleared. I ordered an injector harness for installation the next day.
The harness took about and hour to install, then another hour to button up the valve cover and put the engine compartment back together. The engine ran well and a test drive confirmed the repair.
Now, some expert is bound to comment on this post and say it is impossible for oil in the connectors to cause a miss or an injector problem. However, oil is actually a pretty good insulator, and the oil may only have been part of the problem. I assume that the pins in the injector pigtails were a little loose, allowing oil to get in the contact area and causing resistance across the connection.
At some point in your career you stop always trying to figure out exactly why doing something remedied a problem. If what you do causes the problem to go away and the truck doesn't come back with the same problem, call it fixed and move on.
Thanks for reading, and check back soon.
Bruce
The truck came in with the check engine light on and a miss.
One of the other guys scanned it and found a dead miss in #1 cylinder, and an active code 61, FMI 0 for cylinders 1 and 3.
Code 61 FMI 0 is injector response time too long.
The code descriptor for this is the injector response time is too long, and using the Detroit diagnostic program I found the code for #3 became active when the engine was running, and that injector response time was about .63 seconds as opposed to a consistent .79 to .82 for the others. There was also an obvious miss while running.
The Mitchell information system gave very little diagnostic information for the code, other than saying it could be a wiring or injector problem. I didn't really need to waste time reading just for that information.
I figured I would start by checking harness continuity from each injector to the harness connector at the left rear of the engine. When I unplugged the connectors from the injectors I found each connector full of oil. I doubted whether that could be a problem; injector connectors on especially the pre-EGR DT466 always have oil in them whenever I work on one of those, but there was nothing to lose by finding out.
I blew the oil out of the injector connectors with shop air, then cleaned both the connectors and the pigtails up by spraying them with electrical contact cleaner.
Cleaning oil out of the connectors removed the active code 61.
After plugging the connectors back in, I started the engine and monitored it with the laptop.
The miss was now gone and all injector response times very close on all cylinders. The injector codes didn't come back after being cleared. I ordered an injector harness for installation the next day.
The harness took about and hour to install, then another hour to button up the valve cover and put the engine compartment back together. The engine ran well and a test drive confirmed the repair.
Engine oil can insulate an electrical connection.
Now, some expert is bound to comment on this post and say it is impossible for oil in the connectors to cause a miss or an injector problem. However, oil is actually a pretty good insulator, and the oil may only have been part of the problem. I assume that the pins in the injector pigtails were a little loose, allowing oil to get in the contact area and causing resistance across the connection.
At some point in your career you stop always trying to figure out exactly why doing something remedied a problem. If what you do causes the problem to go away and the truck doesn't come back with the same problem, call it fixed and move on.
Thanks for reading, and check back soon.
Bruce
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