5.3 Flex Fuel Tune

[Biff]

Hello,

I have a 99-2000 5.3 Silverado ECM (Using LS1 Intake [for clearance] with stock injectors and SS2 Cam) that I am using for my project. I will find out the OS once I can get a bench setup. I am thinking in the future of going with Flex Fuel and probably 2 bar SD. Right now I will just run it NA MAF to get the hang of tuning. To start with, is it recommended just to use 2 credits for my initial build and then later on flash the Flex Fuel tune from the 2001 Tahoe that's on the Repository? I am assuming either way you would be spending 4 credits for the 2 ECUs and then whatever it is for the 2 speed SD add on. But could this end up not being a possibility if my OS doesn't match up with what OS the Tahoe has? Am I going about this the right way, or should I just automatically go to the 2001 Tahoe to start with (if possible) and don't bother starting tuning on the original? Also, I will need to Segment Swap to a 4L80e if that matters in the mix. I believe those are free to do though. My FUTURE plans are of course much larger injectors, 78/75 turbo, and I know the Flex Sensor is required as well. Thanks

[5FDP]

Yes you could just spend the 2 credits now and more credits later when you want to change to the flex fuel OS, it doesn't really matter which way you do it I guess.

But if you had the ability to flash the PCM with a flex fuel OS with a GM tool before ever buying credits, that would be the best way to go about it because you'd only spend credits once with HP Tuners.

You didn't say what engine your project was running but just note that many factory injectors are too small for even a decent camshaft upgrade. Like stock 5.3/6.0 injectors usually won't be enough for a camshaft upgrade. For sure on a 6.0 that will rev higher than 5,500rpm, they won't be large enough. Stock LS1 injectors are 2-3lb/hr bigger if you are starting with those.

[Biff]

Thank you 5FDP. I see your name a bunch on the forums and you are always very informative. Sorry, I got the whole setup from the Silverado 5.3. I am just not sure what year it exactly was, but its either a 99 or a 2000. I did plan on running the LS1 injectors for now, so hoping that will be enough. I already grabbed a stock tune from a 99 Camaro, so I can copy over the injector data. Wish I could have used the truck intake, but its going into a Mustang. Not sure if it matters, but planned on using the MAP sensor from the truck to better match the stock tune.

Hmmmm, so if I knew someone with a GM tool they could put that Tahoe tune on it? Makes sense, but didn't even think about that. I may need to ask around first and see.

Thanks again!

[Matt Vardaman]

I have a 2001 Silverado 5.3 with a mild truck cam. I licensed the Pcm and tuned it with a wideband. I also would like to end up with a turbo in a year or two. I downloaded the 2002 Tahoe file and made it match my current tune file. I spent the two credits and made the swap to flex about six months ago. The late model truck flex injectors 50lb/hr are still pretty cheap, so I am running those. It was worth it for me to tune the orginal file with the cam swap/wideband. I don't have a large "performance parts" budget, so I am trying to do the work in practical stages.

If you need a tune file that's flex and already 4l80e segment swapped I'll add one of Matt Happel's files here:HPT - P01 2018 Colorado DBC 2bar flex decapped 80e 500whp base.hpt

and here's my current flex file 12-16-21 2002 Tahoe Ethanol timing lowered in knock rpm ltft on.hpt

[Biff]

Thank You Matt. These should come in handy for sure. I am in the same boat. Trying to do everything as a budget build and not much to spend on this project and slowly building up the parts. I thought I lucked out on a Flex Fuel 2001 Tahoe ECU for $35, but it had a 7 on the 8th character of the VIN. Looks like it should be a Z. They had a few ECUs for $35. Not a bad price to maybe even pick up a spare.

[Biff]

Well, I did find another 2002 Tahoe Flex 5.3 with a 4x4 transmission. Dumb question, but i'm assuming the engine tune doesn't care about 2WD vs 4WD? If I am Segment Swapping to a 2WD 4L80E I should be fine with that ECU.....correct?

Edit: Nevermind. I did some researching and it looks like 4X4 vs 2WD does change the engine tune.

[kevin87turbot]

Well, I did find another 2002 Tahoe Flex 5.3 with a 4x4 transmission. Dumb question, but i'm assuming the engine tune doesn't care about 2WD vs 4WD? If I am Segment Swapping to a 2WD 4L80E I should be fine with that ECU.....correct?

Edit: Nevermind. I did some researching and it looks like 4X4 vs 2WD does change the engine tune.

The 2wd vs 4wd won't matter on the 411 PCM. You'll be altering the tune regardless.

[Biff]

The 2wd vs 4wd won't matter on the 411 PCM. You'll be altering the tune regardless.

So it's only the P59 that you would have to worry about the engine tune mixing with the transmission tune? Thanks

[Biff]

And I just noticed something. My current ECM is the older 09354896 and not a 0411. So maybe I do need to go ahead and get that Tahoe one and use it instead? From what I saw online the 0411 is supposed to have a better processor and more stable. Dont want to waste the 2 credits on the current one if its not recommended.

[Biff]

Okay, so I finally found a true 2002 Tahoe 5.3 ECM with Flex. Paid $60, so didnt do too bad. I had someone try to pass off a 4.3 S-10 ECM as the Tahoe one. "They are the same" is what I heard when informing him of the mistake. LOL This one is a 4WD version, so again it shouldn't matter. When I do my 2WD 4L80e Segment Swap, I saw Kingtal0n had an issue using the 8.1 Avalanche version, so I guess I till try the tune King posted instead? https://forum.hptuners.com/showthrea...l=1#post484080
I need to do the transmission and the transmission diagnostics segments only, correct? Thanks

[kevin87turbot]

Here's a stock 2002 Tahoe Flex fuel file with a 4L80E segment.

Just need to swap the Trans and the Trans Diag segments into yours.

2002tahoe53LFlexfuelwith4L80ESegment.hpt

[Biff]

Thank you Kevin! I will use this one

Here's a stock 2002 Tahoe Flex fuel file with a 4L80E segment.

Just need to swap the Trans and the Trans Diag segments into yours.

2002tahoe53LFlexfuelwith4L80ESegment.hpt