L96 w/LS3 Injector parameters and stock tune refinement. Is it this bad?

[PashkaVR6]

Hello all,

I am not new to tuning but new to the Gen 4 E38 structure, it seems to not respond as it should with fuel.
I have a L96 6.0 (Express Van) with LS3 injectors in it and I thought it'll be a quick edit of changing the injector parameters and will have me a great running engine. What I am finding with the stock LS3 injector table is that its globally pulling -20 on STFT and this trim tapers down close to 0 at wide open. I've tried (what feels like) a million iteration on the injector flow rate table and the fuel trims are still garbage. Also tried a bunch of different injector table changes and it seems that nothing gets the fuel trims globally to +/- 5, which is what I would hope a bone stock engine with a stock exhaust and intake would do. I am starting to think that the base tune for this engine is garbage or the E38 doesn't actually care what numbers you plug in, or of course I am just f-ing up.

I've attached my edited table (stock L96) with the current injector flow rate parameters that are ok-ish (I use this word lightly). I've never seen a completely stock 60k mile engine have such aggressive fuel trims. Is this normal? Am I missing something? Would love some input before I spend a million hours tuning the VE tables with VVT.


L96TuneWLS3Injectors.hpt

[blindsquirrel]

What part number are the injectors? What's the exact year/make/model applications for that part number? Do you have a stock tune file for that year/make/model to copy injector tables from?

[07GTS]

swapping injectors and data dosnt mean it will just work u always need to then adjust the fueling to suit, put the proper LS3 data in and then u will need a wideband and dial in fuel then will be good after that

[PashkaVR6]

What part number are the injectors? What's the exact year/make/model applications for that part number? Do you have a stock tune file for that year/make/model to copy injector tables from?

Injectors are 2010 Camaro SS. Interestingly enough, the Corvette actually has slightly different injector tables for the same part number. One of the issues I had when I put them in was heat soaked lean out, so the temperature compensations where totally different to stock, since discovering that I changed absolutely all the injector related tables over. Engine runs decent, but when left "as-is" the fuel trims are all over, its not just a scaling issue as that would show up with load dependent fuel issues. Mine are just bad everywhere, especially on the low rpm/low load (though I need to make sure there are no vacuum leaks).

This goes back to my question: is this how these engines run or is there something I am not accounting for in the injector tables?

[PashkaVR6]

swapping injectors and data dosnt mean it will just work u always need to then adjust the fueling to suit, put the proper LS3 data in and then u will need a wideband and dial in fuel then will be good after that

There is absolutely no chance I am going to tune VE because of a sensor/part that should always be a constant. Tuning an engine using sensor scaling or tuning to mask bad data in a flow device is a horrible approach to tuning, these things are calibrated and there is only one right answer. Having proper hardware data should let you change a part (assuming you have a data sheet for it) and everything should work the same. If I know that +/- 15% LTFT with no particular pattern is a norm, then I don't mind spending the time to make it correct (and may as well add a cam and such), I just don't want to tune over bad sensor/hardware data.

[blindsquirrel]

If your assumptions were correct then there would be nothing to be gained from tuning VE/MAF on a completely stock engine that's had no changes since it left the factory. This is not the case. I am sorry.

We cannot see what you are calling 'bad' without a log file. Or should logs not be required in this case since it's all stock parts and everyone should already know what it would look like so what's the point?

[PashkaVR6]

If your assumptions were correct then there would be nothing to be gained from tuning VE/MAF on a completely stock engine that's had no changes since it left the factory. This is not the case. I am sorry.

We cannot see what you are calling 'bad' without a log file. Or should logs not be required in this case since it's all stock parts and everyone should already know what it would look like so what's the point?

As I mentioned, the LTFT are +/-15%; when disabled the STFT are 20+ in a lot of spots but +5 in others (but still similar delta of nearly 30). So either I am missing something in the injector data, or the factory GM tune is crap and I actually do need to tune a stock engine? That is what I need an answer on: "Yes, GM tunes are crap", or "No, you are messing up and this is how to properly change injector data..."

In my mind a bone stock setup with fairly low miles should be in +/- 5 on fuel trims, and is usually the case in any car that I've monitored this in. At 10% all german cars that I am aware of will set a check engine for rich/lean. "Tuners" will often bump these limits up to +/- 30% to band aid their work, this approach has always seemed like a hack way of doing things to me, and how I feel about tuning VE to band aid a mistake that I may have made with injector data.

I ordered a set of stock L96 Flex Fuel injectors just now. Now I can use all the default settings and have closure on this subject. I am hoping for nice fuel trim tables, will update in a week or so.

[blindsquirrel]

It's slightly different for different platforms, but for instance, looking mine up it's got to be a whole loooong list of conditions met first, and then LTFT at 24% for 3 minutes to set System Lean codes, and same but -17% to set System Rich codes. Basically it'll only set codes when it's completely out of options, not when it's first suspecting something might not be exactly as it should be.

In the end, it really does not matter if the injector data is slightly off and you slightly compensate with VE/MAF tuning. 5+5=10, 5x2=10, 2x2+6=10, 1+1+1+1+1+1+1+1+1+1=10, etc. It's the end result of a whole bunch of calculations that determine fueling.

[RobZL1]

That is what I need an answer on: "Yes, GM tunes are crap", or "No, you are messing up and this is how to properly change injector data..."

Stock tunes are in a much tighter range than +/- 15% with no discernable pattern.

[blindsquirrel]

I think it is highly unrealistic to assume that if you swap injectors and copy in all the relevant injector data that you will not have to touch the airflow models, and that if the airflow models are off after the swap then that must mean something is wrong with the injector data. You've created a brand new thing the factory never made a calibration for.

[blindsquirrel]

2006 Trailblazer 5.3L vs 2006 Trailblazer 6.0L

These both use the exact same injectors yet have different injector data. In fact other than camshaft profile and cylinder bore, everything is the same on both engines.

screenshot.13-01-2021 23.27.41.png

So... which tune file has the "correct" data for injector pn 12580681?? Answer: they are both correct, they just made up the differences elsewhere in the calibration. Either set of injector data plugged into the other file would be "correct" AFTER tuning.