Another dumb fuel pressure question.

[vatman02]

I would check your injectors because I run the Mototron 60lb injectors with a 222/224 cam and my VE in the lower area doesnt go below 22%.
Just a thought!

i think alot of the problem is the altitude i have 20% less baro here thus 20% less air anyway i just sold the 60's and am waiting for some 42's

[redhardsupra]

That's what it seems to me... different ways of adding different amounts of the components to obtain the same result.

yes, but some of these tables describe very particular behaviors, like the short pulse issue is very weird and does not follow a normal behavior, so it's not a simple lookup but lookup with modifiers. it would be nice if they just made it into a one bigger model instead of go case by case, but i guess this is simpler to deal with from a simple cpu's point of view.

i could make my IFR to be artificially lower at the MAP/MANVAC where i idle just to produce the right idle, but then if i happen to be driving at the same manvac (but different RPM, so it yields a different VE, thus airmass!) then my fueling is going to be off because it's dumping more than supposed to. and you're chasing your tail. again.

there's no point in avoiding understanding of these issues. we cannot ignore them. as much as i'd like to ignore gravity every time fall on my ass, it's not going to go away, so might as well learn to anticipate it.

[dfe1]

It's a mistake to think that GM engineering always operates on consistent, logical principals. In many instances, I've found that the personal preferences of the enginer in charge of a particuar project are the controlling factor. This is fairly apparent if you examine the many about-faces GM has made over the years. One that comes to mind is the reverse cooling system used in the LT1 engine series. I remember the cooling system engineer showing all types of documention to illustrate the superiority of reverse cooling. That was in 1991. By 1996, when the LS1 engine was introduced, reverse cooling had gone the way of carburetion.

Calibration practices are similarly random, based on the preferences of the individual calibration engineer. I fully agree with RHS that it would be helpful if we had a full understanding of all the modifiers, but I'm not so sure that we'll find a consistent enough pattern to uncover the method to the madness. I tend to think that a lot of modifiers are included to address unique conditions which may not exist in some engine combinations. (Have you ever noticed that a number of tables are filled with 0s or 1s in some stock calibrations?) I'm farily certain that some values are the result of altering one calibration to fit a different engine/drivetrain/vehicle combination.

[redhardsupra]

i dont want a consistant pattern, i just want a consistant method to reveal any patterns we need

lately i've been 'entertaining' myself using some general modeling tools like multi-variable non-linear regression to optimize parameters we cannot measure empirically. it seems to work, i just need some time to verify it.

I haven't used it on short pulse stuff yet, but it'd be interesting to see if it'd work. anyone got logs with very pronounced problems due to the short pulse not being calibrated for aftermarket injectors?

[ViolatorTA]

pronounced such as?

[vatman02]

might this be what you are looking for if so i will post it up i didnt log ibpw for the one that has the 60# injectors the other is the stock 28's what i dont get is why the gm injector flow and the calculated flow dont match when i was logging at idle (and didn't save) i was seeing pulse widths of 1.6-1.8

[vatman02]

man i suck at this i cant get the pics up so i posted both loggs you can see what i was saying without even pushing play