7747 tuning again

[rr]

The real test is how much fuel the pump can move. If it can't provide
enough fuel, pressure will drop, then injector flow drops. The higher
the pressure the pump is required to maintain, the less it will flow.

The VE tables: I'll use straight decimal numbers here. The max VE value
is 255 (a byte). Each table has a lookup done, with the results of the two
lookups added together. This value can not exceed 255 (that's 100%).

If one table has 255, and the other has 30, the result is 285, which can
not be stored in a byte. The software checks for this condition, and if true,
will set the VE to 255 (100%).

If one table has 155, and the other has 30, the result is 185, which can
be stored in a byte. The end VE value will be 185 (72%).


BobR.

WEG1192 at aol.com wrote:

> Bob,
>
> I raised the BPW constant to 140 since the engine has 10 more cubic inches
> than a 350. I used Tunercats equation with a 5.9L vs. 5.7L engine. As for
> EGR, I raised the TPS% EGR ON to 99.9% and the EGR OFF to 99.2%, or something
> real close to that. I realized after I sent this post that I haven't checked
> the fuel pressure under load, only at idle. I figured that idle was the worst
> case for the regulator to handle since it is bypassing the most fuel at this
> condition, but I realized that I could have a stuck regulator bypassing too
> much fuel under load. Its a stock regulator and the PSI is too high so maybe
> there is something wrong with it. As for AMC engines being gas hogs, does
> that mean the brake specific fuel consumption of 0.45 is not vaild for an AMC
> engine, since that would account for high fuel use with less power output?
>
> I'm not sure what you mean about adding one table at 30% and the other at
> 100% and only getting 100%. If my main fuel table was at say 70% at 3200 RPM,
> and the adder table at 100% at 3600 RPM, shouldn't I get the equivalent of
> 170% at 3600 RPM? My problem was not knowing what 170% is. If the VE tables
> are turning on the injector at its maximum rate at 100%, 170% means nothing
> from a fuel delivery standpoint, right? But this is a moot point since I am
> not reaching 3200 RPM on the hiway. This engine seems to be a low RPM mule.

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