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Pete. (l33t FS)
Pete. (l33t FS) MegaDork
1/25/21 11:57 a.m.

In reply to Scotty Con Queso :

While true, 90% of the tuning you can do, you won't NEED to.  Things like acceleration enrichment are handled by the computer modeling how much fuel is puddled in the ports at any given time.  Way complex but also it isn't really going to change either, unless you move the injectors. And the fuel injection modeling is extremely precise, and you won't need to touch them if you stick to OE injectors.  (from ANY GM - you can just copy the injector tables from the appropriate tune)  Better aftermarket injectors come with Excel files you can copy and paste the characteristics from.

Most of the other tables are things like how much torque the A/C compressor requires at given high side pressures,  how much torque the engine requires to turn at whatever it thinks the oil temperature is, etc.  Stuff you won't need to mess with because you're not affecting it.


Standalone computers are "easier" to tune because they are a lot more basic, like swapping jets in a carb.  And when you try to get the tune "Good" instead of "runs", you find that there are a lot of limitations.  A perfect tune to a cheap (sub $10k) standalone is a crappy tune for an OE computer because there are so many compromises.

Scotty Con Queso
Scotty Con Queso SuperDork
3/23/21 9:50 a.m.

Bumping this up. Maybe one of you can help me out. 

For my swap, I have an early gen III drive by cable with the return style rail and on rail regulator. My Colorado has a returnless fuel system. Can I just swap to a returnless truck rail? If so, do I need some sort of external regulator. I'm using the stock Colorado fuel pump (good to 500+ hp) and I've heard rumblings that it has an internal fpr. 

Furious_E (Forum Supporter)
Furious_E (Forum Supporter) UltraDork
3/23/21 2:35 p.m.

In reply to Scotty Con Queso :

Yes you can swap to returnless, yes that will require an external regulator. Not sure about the internal regulator in your Colorado's fuel pump, would it be possible to run it to a fuel pressure gauge and see what psi it's putting out? 

I've used the C5 'Vette filter/regulator combo on both of my swaps, but that won't really apply in this case, as you're not trying to adapt to a chassis with a return style system.

kb58 SuperDork
3/23/21 2:57 p.m.

Starting with a standalone ECU, getting a basic tune takes half a day - that takes care of the "racing" part of the power curves. Getting the car to run like an OEM vehicle under all conditions... that takes months of additional tweaking.

The easy way out is to stick with the OEM computer, but if the engine has been significantly modified, yeah, plan to stall often pulling away from a light..

Somebeach (Forum Supporter)
Somebeach (Forum Supporter) HalfDork
4/27/22 12:19 p.m.

Old thread, I know.

I thought I remembered someone talking about using the Chevy Express vans as a donor. That was either a good donor or a more challenging donor to use, but I didn't see that when I read back through this thread. 

Also did all the express vans that came with the 4.8 have the 4l80e? 


RacetruckRon Dork
4/27/22 1:39 p.m.

In reply to Somebeach (Forum Supporter) :

Look at the hubs, 8 lug hubs should be 4L80e with either a 4.8 or 6.0.

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