So just got done rebuilding my engine has the afo cam re pinned the ficm and has brand new fans diesel 100 over injectors and s&s 12mm cp3 I compression tested it before dropping the motor all 360-380 cold I have rechecked valve lash made sure they were fine cylinder 7 in staying pegged out at +7.0 and cylinder 8 bounces from 13 to 15 but there is no fuel knock I’ve ohmed my injector harness they check out switched ficms with known good one I’ve swapped injector from cylinder 7 to 5 and cylinder 7 is still stuck on 7 no fluctuating whatsoever I’m assuming cylinder 8 is trying to compensate for cylinder 7 not firing just my theory I can’t think of anything else anyone had this issue or think of any other test
Lb7 injector issue balance rate stuck at +7.0
- Thread starter Compoundlb7
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- afo bad ecm lb7 injectors
Looks like injector 3 is not contributing much and the ECM us trying to add more fuel to get it to balance with the rest. #6 is probably a fluke and is a result of number 3
Usually the first thing to look at when you just got done putting injectors in / doing a rebuild is the connection nuts right at the injectors. The connection pigtail is suspect too. But it's more common to have a loose nut.
Whats the main rate mm3?
Pop the valve covers off and re torque the nuts
Usually the first thing to look at when you just got done putting injectors in / doing a rebuild is the connection nuts right at the injectors. The connection pigtail is suspect too. But it's more common to have a loose nut.
Whats the main rate mm3?
Pop the valve covers off and re torque the nuts
I have popped off valve covers tightened the nuts even swapped out harness with another and rechecked valve lash on this cylinders with bad readings but I know the engine has great compression
I don't know if the edge scanners show injectors based off firing order or cylinder numbers. I know efi live on the LB7 and possibly others did this. Or at least it did on mine and some others reported the same. Sure messes up diagnosis. Apparently the Tech2 scanner gets it right with numbers based on cylinder and not firing order
If your edge is showing firing order #3 and #6, wouldn't that imply based on your AF order cam that it's injectors in cylinder #2 and #6 that are the ones with bad numbers?
Try swapping the injector in cylinder #6 with another and see if it follows
Just a WAG, but double check your pins in the connectors to the FICM, too. When you were doing your repinning, you might have pulled other pins out just slightly and now they arent making good contact.
I thought it would be 7 and 8 that is showing bad or no
I will check this woul a lb7 shut half the bank like lly does it one injectors isn’t firing like tractor mode?
I have popped off valve covers and checked injectors nuts even swapped out a harness and swapped injectors and it stayed at the same cylinder staying firmly at -7.0 no bouncing around like the rest unless I changed the wrong injectors I guess I might be confused on which cylinders are which now on my edge with the afo came can some help confirm which cylinders are showing these balance rates with the new firing order because the edge doesn’t know or change I’m assuming
Use the image I posted above
I spoke with Dan from Dan’s diesel he said #8 cylinder is #3 on the edge screen now he believes the injector isn’t firing or compression issue I’ve ruled out the compression I’ll swap out number 8 with cylinder 6 and see what happens
That’s what I thought so I swapped out 7 with 5 and cylinder #7 still pegged at -7.0 balance rate #3 on the edge monitor is now #7 from what I understand
So wouldn’t -7.0 rate that doesn’t move what so ever isn’t that one that’s not firing or getting anything causing the one to be so high to compensate for the cylinder that’s right before it in firing or to be so high
Negative numbers mean that cylinder/injector is contributing too much to the crank rotation and the ECM is seeing a faster rise in RPM right after that one fires. It is pulling back fuel on that one trying to slow things down.
A high injector followed by a low injector based on firing order can mean the first one isn't contributing enough and it's trying to add more to that one and pull some out of the next to keep things smooth. This doesn't always mean both are bad. The one that fires before the next is usually the suspect though
A low injector followed by a high can be the opposite. The second in line might be the bad one.
Sometimes it's not easy to know for sure and you either play musical chairs with the injectors trying to see if the numbers follow. Or sometimes it makes more sense to just do all 4 on one bank or all 8 if it's showing issues on both banks