Turning off Injectors (cylinders) to find miss. Please Help!

[ricky0677]

I have a 2006 LBZ. It developed a knock and started missing (running rough). When I turn off cylinders with EFI Live it makes no change in Engine at all except when I turn off Cylinder 4 which causes engine to run smooth. This was opposite to what I expected. When I had my shop and repaired gas engines in the pre computer days I had a SnapOn Diagnostic Tool that would cut out cylinders and when you cut out the bad cylinder there would be no change to the engine RPM and when you cut out a working cylinder the RPM would decrease and the engine would miss even more.

Please help me find my bad injector. :shock::redface:

Thanks, Ricky Smith

[kajon25]

did you figure it out?

[ricky0677]

did you figure it out?

Yes but not with $1000 program and laptop. I changed the injector that made the least change in RPM when individual cylinders were killed and miss and knock was still present. I took my $5 Harbor Freight stethoscope and listened to each cylinder by touching stethoscope to the head close to each injector. The cylinder with the bad injector had a noticeable knock.
Changed that injector... problem cured.:banana:

[joecar]

This probably means the cylinders are mis-numbered in EFILive.

[jessek]

This probably means the cylinders are mis-numbered in EFILive.

Is this a possibility? I have come across this topic a few times and I always thought that since the cylinder order is different (starting at the passenger side front for number 1) that it was a user mistake.