Tip for anyone diagnosing duramax injector issues with HP Tuners

[Noah63Nova]

Hey All, just wanted to share an experience I had while diagnosing injector issues on a LB7 duramax. Hopefully this can help someone in the future and is not repetitive information. HP Tuners provides the ability to disable injector(s) within the VCM Scanner. This is a great asset when diagnosing injector issues. That being said, do not trust that the tool is disabling the injector that it says. Ex: Disabling injector #4 may not actually be disabling injector #4 it may be #6. It is also not by firing order. Just something to look out for instead of chasing your tail. As a reminder, duramax is even cylinders on the drivers side and odd on passenger.

In my case, all injectors ohmed out perfect and no check engine light/codes so the problem child was not apparent. I borrowed a scanner from a friend and was able to disable injectors with his tool. This disabled the actual problem injector. You could also buy the tool to cap injector lines to find which injector is the problem.

[Stroked06Goat]

Great info. So you are saying you can find there is a problem injector, you just cannot identify which one is disabled with VCM Suite?

[TheMechanic]

You are much better off diagnosing an injector issue with the balance rate. I rarely use injector disable unless there is a compression or engine knock issue I am diagnosing. I use my MDI2 and Tech2Win or Techline connect so I am not familiar with the injector numbers being incorrect. Never heard that one but someone needs to correct that pronto.

[Noah63Nova]

Thats correct.

[Noah63Nova]

I agree. HPT is all I had initially to diagnose which is how I ran into this. In this case, it was a fuel knock from a stuck open injector so checking balance rates was not an option (could not get a consistent reading with an appropriate fuel rate).