How is air flow determined?

[RSpengler]

If I am currently running 13.2:1 air fuel ratio (@15psi) on my stock 17c, utilizing Ultimate 50# chip for fueling, and I change my turbo to say a TE60, how does the computer know that the air mass is much larger at the same pressure with the bigger turbo? Im scared of leaning out when I swap turbos.... Basically, I want to know the how the ECU or the Ultimate compensates for turbo changes (if it does).
-Rob

 

[gmcturbo]

Re: How is air flow determined?

check the tuning forum and jsmanufacturing's stickys. those about cover it...

 

[MRKING]

Re: How is air flow determined?

the ecm doesnt calibrate itself and the fueling tables have to each be changed slightly to fit your exact build once any changes are made ...

 

[ghettosled]

Re: How is air flow determined?

13.2:1 is already super lean and most likely detonating if it is accurate. Most tuners here will suggest high 10s low 11s for pump, but it all depends what you can get away with (timing vs. boost)

 

[RSpengler]

Re: How is air flow determined?

Well, thats not a wideband measurement, that is read from my ATR Air/Fuel - knock gauge. Every once in a while when I get on it the knock alert will activate, but its not a constant thing.
-Rob

 

[dgoodhue]

Re: How is air flow determined?

I change my turbo to say a TE60, how does the computer know that the air mass is much larger at the same pressure with the bigger turbo?

I am just looking at the air intake side. If nothing else has changed (intake/heads/cam/rockers) the only air mass difference between a TE60 & 17c at 15psi would be due the air densisty due to temperature. They would flow the same volume of air. (Personally I don't think their would be much of an air mass difference at 15psi) The stock turbo is at its most efficient boost level at 14 psi, while a TE60 is a much higher boost level. At higher levels the air mass difference will be come more into play (also intercooler capacity comes in to play as well)

As for fueling the higher PSI levels. The stock ECM code uses a boost multiplier for each boost level (ie its sort of crude to begin with) A TE60 is small enough that you could use the rich version of the stock injector ultimate with a combination of a AFPR or if you using the 50# program, 50# chip ultimate has richer fuel programs. The ECM does have intake temperature table, but its too coarse for this usuage (IMO its best use is for alky)

 

[JSM]

Re: How is air flow determined?

You will need a custom tune to be right. This can be done via someones service on here, or learning to tune yourself. As mentioned I posted some hints, tricks to get people started.

It still boggles my mind how people thing when X part is bought a chip is sitting right next to it on the shelf that will work. IT DOESN"T EXIST until you get or have it created. I will be honest, I sit and LAUGH at some of the trucks on here, and et's they are pulling with pages full of mods. It provides me good entertainment. Then when someone actually does some tuning, people are amazed. (Nolan first in 10's on stock ecm, jeremy running low 12's on stock turbo, there is a small list of tuned trucks).

That AFR gauge on your dash should only be installed during the month of December as all you have is a light show, aka christmas lights.

 

[VermontTy]

Re: How is air flow determined?

I sent my AFR gauge packing a while back. Although it looked kinda pretty, it was as useful as a chocolate teapot....

 

[TYTILIDIE]

Re: How is air flow determined?

I sent my AFR gauge packing a while back. Although it looked kinda pretty, it was as useful as a chocolate teapot....

I know Im getting rid of mine soon as I can afford a wideband.