To try and help me visualize how the 2 fuel tables worked/looked i have created an excel workbook which adds the 2 tables and graphs them. (a link to it is at the bottom of this post)

This raised more questions.....
1. In some places the combined VE exceeds 100% ?

2. Why does VE2 have such a massive chunk missing/peak around 4500. (i have not modded VE2 yet,this is stock)

3. If the VE2 table was smoothed and the "under the line" actual/total values maintained what would the smoothed combo table look like?

4. And i guess the big question is, how will the smoothed combo run, should i burn it and try, am i likely to damage anything?

Excel VE1 and VE2 plus a smoothing routine on worksheet2

 

1. If one's *trying* to force the injectors static as quickly as possible to min them being erratic, for too long MIGHT be a reason.

2. Post what your looking at.

3. Smoothed?. What's smoothed mean?

4. If your in doubt about something, NEVER run it. It doesn't take long to knock the rings out of an engine. Again, time for an ecm bench if your wanting to try radical/unknown stuff.

 

Grumpy
All the VE1 & 2 table values are from the stock chip. whick is my baseline reference for 1st time mods,
I wanted to take your previous advice on adding VE tables 1 and 2 togethor to see how it looked.
I just didnt understand why over 100% would be asked for - are you saying that GM intentionally do this to max out the injectors ?

The hyperlink(at the foot of the post) to the excel sheet has all the stock values listed and graphed etc on sheet 1, the stock VE2 table has a massive dip and being curious I wonder wonder why ?

smoothed means "not so jaggy" with respect to how the graph looks to the human eye.

It seems damn near impossible to get a good blm count in all cells, so if I tune the ve on the cells that I do have a good count on and then use these as a blending basis for the neighbouring ones I havent got a good count on...... would this work.

basically should the graph look kinda smooth.

 

I can't speak for what they were doing, only what it looks like to me.
You give the engine what it wants, not what you think it needs, sometimes things look strange.

Do what works, ie makes the engine happy.
Don't forget the spark table has a huge effect on things also. You looking at how to control the recation in the chamber, and that includes fuel spark, and all the mechanical bits.

 

i will give it a try this weekend (weather permitting) and let you know how it performs.

 

The VE is not the duty cycle, it's the volumetric efficiency. Duty cycle of 100 is static. VE over 100 means the engine is taking in more air per 2 strokes than the displacement of the engine (with a MAP factor though, where the calculated mass intake is greater than the mass of the displacement at that MAP pressure and density).

The dips and bumps can sometimes be attributed to fuel pressure harmonics, where standing waves can lower the pressure at the injectors while the pressure at the regulator is good. It can also result from air pressure harmonics with the "tuned ports" runners.
But, if the torque curve doesn't resemble the VE curve, it's likely fuel pressure harmonics which need to be compensated for to make it back to the correct amount of fuel injected.

 

Thank you, a light just went on in my head, that helps a lot.

So i guess then, that to be accurate, i am just going to have to make the engine run in a particular high rev/map range and check the actual blms recorded in winaldl.

5000 RPMs here we come, Oh i wish i could log at a faster speed than once every 1.2 secs............

 

Harmonics, or dynamics?.

Can I have a quick explaination of what a *standing wave* is?.

 

Maybe it's not exactly standing, but when all of the injectors in one bank fire, the pressure momentarily drops, and when they stop it builds, and this is repeated. At certain frequencies (RPMs) this pulsing approaches the natural frequency of the system (rail, stiff rubber lines, etc., and the pressure at the injectors can vary wildly.
If you were to build an R7 (non fuel injection fuel hose) rubber fuel rail, this would virtually dissappear - and yes, I have done this - this year even - and yes I do have logged data to prove it - even logged fuel pressure and WB A/F, and base fuel maps that look crazy with hard plastic line that is deadheaded to the injector from a distribution block, to rubber line deadheaded at the injector, to large ID plastic line dead headed at the injector, to cross flow rubber line system, to deadheaded with an accumulator/damper, to deadheaded with short rubber sections to act as dampers. You could litterally feel the vibrations in the lines when plastic was used, and you could feel the rubber absorbing the damping. The plastic line base fuel maps had HUGE spikes and dips in it (amplitude depended on diameter), at regular frequencies, where there were pressure dips at 1200 RPM, spikes at 2400, and dips again at 3600. With the rubber system, the fuel map looked exactly like the torque curve, and the pressure was the smoothest ever seen.
So, moral of the story: if you change fuel system components or design a different rail assembly, your fuel map may change drastically. Fuel pressure harmonics have been plagueing auto makers since efi, which is why there are such things as expanable fuel rails and accumulator/dampers. Even at the end of all that, sometimes the calibrators just cover up the harmonic dips and bumps with more or less fuel.
Sorry for rambling so much,
Later

 

Interesting, this is something that I've thought/wondered about myself. I have seen a fuel pressure regulator go into oscillation at a certain engine RPM & load point. I figured that it had to do with a particular fuel flow through the regulator. Now, maybe not. Could have been a resonance in the fuel system.

Even though a lot of cars run the turtles in the tank after the pump, the 3.1l ('90-'92) f-body's run a pressure side damper up at the front of the engine. This may be a part to look at installing on other systems.

RBob.