I just installed a set of LS2 injectors in my truck, since the stockers were seeing 102% duty cycle. I pulled a 2006 stock GTO tune from HPT repo, copied the injector data, and dropped it into my tune.

I reset my fuel trims before the first start, and logged some data. Both LT and ST fuel trims occasionally hit 13s. Still need to weld my wideband bung into my new headers...

I was under the impression, once you supplied the ECM with the injector data, it would know how to control them, and you would get the same amount of fuel where you originally had it...

I guess not. Do I need to retune VE and then MAF now?

 

It may mean that the factory injector data was incorrect from the beginning.

 

That's possible. I'll look into that. But am I correct thinking that once the injector data is input correctly, that the ECM will compensate for all fueling adjustments? Should inputting the injector data be the only adjustment to the tune?

Or will anyone who upgrades their injectors need to retune their VE tables using the afr error histogram? And then the maf?

 

If the new injectors and injector data match, and the car was tuned correctly prior, you should literally be able to swap injectors and upload the new data and have it run almost exactly the same as before the injector swap. I did this on a friends SS. It was tuned on stock 28# injectors, we swapped to Mototron 60# injectors, uploaded the new data and started the car and the wideband was the same as prior to swapping injectors.

 

I believe my problem is that the injector data was copied from a car that had a returnless fuel system that was not vacuum referenced, so it has some different fields in the tune that my truck does not have, since it was a return style fuel system, with a vacuum reference. I have converted my truck to non return style, with no vacuum reference, by using the corvette fuel filter, and have used injector data from a vehicle with the same setup. 2005 GTO auto.

Ill post both tunes so you can give your opinion.

 

The tune titled NNBS+InjFP is my current truck tune, and the other is the GTO tune where I sourced the INJ data from.

The Short Pulse Adder and the Minimum Inj Pulse fields have different column headings in each tune, so they dont match. How can I fix that?

There are some tabs that dont even exist in the source tune. Am I using the wrong tune file for my source? I'm running injector part number:

LS2, 34lb/hr@58psi, GM # 12569113 0280158049. 34 @58

And yes, the truck was tuned perfectly before the Intake manifold/tb/injector swap. So in theory, once I get the inj data corrected, it should need very minor tweaking. It runs ok now, but not perfect. I'll attach a log and config also, so you can see the fuel trim corrections.

 

Is that average or max?

 

This is a cold start, so it adds fuel until it comes to temp, then the LTFT pull fuel. Disregard my wideband reading, it isnt plugged in.

 

The max it pulls is 13%. I just attached a log, but I'm still on 2.24 until I finish this retune. I'm not ready to relearn everything that comes with 3.0.

 

You cant just copy and paste the injector data from the GTO into your truck because the fuel system is different and the ECM's aren't even the same.
In a perfect world if you have correct injector data and change injectors with correct data also the tune will be the same. Even then it could still require some tweaking.

 

Try looking for some other LS2 tunes. I believe GM used different data for different cars.

I have the LS2 injectors in my C5. But I started with them from the get go. So even if my data isn't correct, I tuned around it. Car runs excellent.

 

A max (and at the same time min) of 13 is not really that far off. Ideally I'd like to keep it within +10/-10 but that's just being a perfectionist.

13 swing with trims is normal and I doubt you'd get much more precise than that. It's more the average that you have to worry about.

 

I am not sure about the LS2 injectors into a truck. I thought those were different lengths. Maybe your using spacers or whatever, but IMO, if this is going to be a major issue, and you can, swap to the white 36#/42# 3.8 supercharged injectors. Those have good data for them. A friend swapped them in a 02 Camaro SS and the tune stayed exactly the same.

 

My fuel system has been modified to act like the GTO's returnless, non-vacuum referenced, fuel system. How should I have handled the calibration?

I've found a tune for a Trailblazer SS with the LS2, but they seem to be 30# injectors. If what ^^ he says is true, this wont work either, since its not the same ECM. I'll give it a shot anyway.
Well it's good to know that even with my inj data issue, its not too far off.
Thanks for the tip.

I am running an intake manifold from a 2007+ truck, or the Trailblazer SS 6.0. Same intake, but they came equipped with various size injectors throughout the years. I am running the fuel rail that came with the intake also, no spacers. I appreciate the suggestion, but I dont have those injectors, and I dont have that data.

How do you copy data from a chart that increments in 500rpms, and paste it into a chart that increments in 400rpms? Does HPT have a tool for that?

 

You have to extrapolate/interpolate to the new step size using some math tool that has extrapolate/interpolate functionality.

 

I disagree. On a well tuned engine, the trims will not swing more than +5/-5.

 

Throughout the course of an entire year? Maybe on a bone stock motor in Southern California. Anywhere else, or on a modded motor, good luck getting +/-5% year round.

 

Yeah I've yet to see a car that's even within 10, much less 5.

Maybe at a steady state driving, like cruising on the highway or idle...but to not have any trim swing more than 5 or less than 5 throughout the entire RPM and kPa range...ain't gonna realistically happen.

 

Exactly. Statement makes me think he doesn't tune much or is only talking about WOT or something.

 

Yes, the entire year... a well tuned engine doesn't care all that much about the weather or the season.

As for the "good luck getting +/-5% year round"... I can assure you that luck has nothing to do with it.