Cascade Crew

91RSVert · Posted: Wed Mar 24, 2010 10:05 am Post subject: q on tuning

So now that I have my side to side problem fixed, on to tuning this thing.

I am seeing that one area of my ve table is reading 103%. Does that imply I dont have enough injector? If the motor was "boosting itself" that would be reading on my kpa right?

Twilightoptics · Posted: Wed Mar 24, 2010 1:15 pm Post subject:

Could be with your coolant modifiers, your ve table would be off. They are just numbers in alot of GM cases. Even though it says 103% doesn't mean it's seeing 103% Real life volumetric.

91RSVert · Posted: Wed Mar 24, 2010 1:32 pm Post subject:

coolant modifiers? Confused

91RSVert · Posted: Wed Mar 24, 2010 1:38 pm Post subject:

http://cascadecrew.org/phpBB2/garage.php?mode=view_gallery_item&type=garage_mod&image_id=1107

Dewey316 · Posted: Wed Mar 24, 2010 1:52 pm Post subject:

Do you see how the equation is the main table VE divided by the change coolant temp modifier.

Post a screen shot of that table.

91RSVert · Posted: Wed Mar 24, 2010 2:00 pm Post subject:

???

http://cascadecrew.org/phpBB2/garage.php?mode=view_gallery_item&type=garage_mod&image_id=1108

I dont tune tell the car is above 175deg.

Dewey316 · Posted: Wed Mar 24, 2010 2:18 pm Post subject:

That is part of it, there is another table for charge air temps. The computer is adjusting how the fueling reacts and VE changes based on intake air temps.

You should also have other stuff that modifies fueling based on other factors such as coolant temp.

Also remeber that the VE is not duty cycle. Does your logging software log duty cycle, and actual calculated VE? There are lots of modifers that act on the main VE table.

I guess I am maybe jumping in late on this, what computer is this for?

91RSVert · Posted: Wed Mar 24, 2010 2:24 pm Post subject:

I dont know what all this program will do. Its to do alot of crap I cant make it do even following the downloadable manual. Would think after 2.5 years I would know more, but I dont. No shop here will touch my car, and nobody in the area runs this program on a gas motor.

It will log injector duty cycle. Think I should turn it on and see?

LS1b pcm, with 2002 express van tune.

I can buy a custom crank wheel, coil packs and run coil per cyl Twisted Evil

Dewey316 · Posted: Wed Mar 24, 2010 2:28 pm Post subject:

logging duty cycle will answer you really fast, if you are running out of injector.

The VE will be effected based on what parameters you put in for the injectors, coolant scalars, etc. Anything in the computer that effects fuel calculations will add/remove fuel ontop of whatever is the in the main VE table.

Also, i noticed that the max value for the VE table is 5~something. The number in that VE table may or may not be a VE percentage, it may be some other unit of measurement. You might want to find out how that computer actualy uses that table. It could be something base in g/sec or something.

Alphius · Posted: Wed Mar 24, 2010 2:50 pm Post subject:

AFAIK:

VE (volumetric efficiency) is a ratio of the volume of air&fuel actually entering the cylinder to the theoretical maximum volume that would enter the cylinder given a standard atmospheric pressure. Therefore, VE=(actual efficiency/perfect efficiency). The way the ECU uses this information is backwards, actually. It measures the volume of air entering the engine (or measures the load of the engine which can be extrapolated to air), and it knows how much fuel the injector will spray for a given amount of open time. It also knows how much fuel to spray to make a stoichiometric ratio at 100% volumetric efficiency. These things are known because of the injector constant, and MAF scaling table. (Unless it's MAP, but that's simple too because manifold pressure can be used in nearly the same way as mass-airflow data as far as the ECU is concerned.)So, the ECU needs a way to account for less-than-perfect conditions. It doesn't know what the VE at each RPM/MAP point is unless you tell it with the VE table (and there are other fuel-trimming tables, but we care about VE right now).

Here's a sample fueling equation that incorporates VE:

Alphius · Posted: Wed Mar 24, 2010 2:51 pm Post subject:

91RSVert · Posted: Wed Mar 24, 2010 4:37 pm Post subject:

Alphius.. I had to go get some food so I could focus on all that, whew.

About it just knowning air, and calculating the injector length, I knew that.

I tried to read for a good 3mo or so before I got into this. But my largest problem in life is comprehending what I read (oh and spelling too!!). I do way better seeing it done, and someone "dumbing it down" for me.

I'm mostly worried that if something is at 103%, is something not large enough to handle everything else?

Twilightoptics · Posted: Wed Mar 24, 2010 6:48 pm Post subject:

Alphius · Posted: Thu Mar 25, 2010 7:29 am Post subject:

91RSVert · Posted: Thu Mar 25, 2010 7:49 am Post subject:

Oh, its modded. Ive been hacking at it for 2.5 years...
1. The ve table for it was much much flatter.
2. My car needed alot more idle air then the van to even start.
3. Changed the speedo output.
4. Had to swap vats from one style to other (yes, it still works)
5. Been playing with egr
6. Had maf running for a while, kept getting errors. Went to install a 85mm maf, but couldnt decide on a route, then it got stolen and havent gotten a new one. So maf is disabled.
7. Tune is for an automatic, I am stick right now. I think that is some of the issues I am having.

My onboard vac meter reads about 1.5'ish on a wot run. I am assuming the modded gm dual snorkle is doing decent for the setup?

BTW, I have been doing this w/o a wideband also. Shocked

Alphius · Posted: Thu Mar 25, 2010 9:03 am Post subject:

91RSVert · Posted: Thu Mar 25, 2010 9:51 am Post subject:

Yea, I'll send you my latest, and find the stock one too. But it will be later tonight.

Two biggest issues..
1. When I start the car, let it warm up it idles just fine as thats what I set my grams ps(here on gps) too. But I turn the car off, come back, it requires a complete different gps... like its stuck on fast idle. I have it set now so when it first warms up, its adding gps at full temp and sometimes feels like its going to stall. Then on restart its still fast idle, but not so bad it screams.

2. Since I have maf delete, I know it plays tricks with timing tables. I cant figure out which timing table I need to play with. Id like to remove some timing in my idle/low rpm areas for lope and fuel savings. Then of course add some at my drive and wot areas.

Another, but I know how to adjust, just havent. Since I'm a stick, I push in the clutch while coasting to a light, it will still stay reved as the pcm is still reading mph. I need to make it remove gps faster at the upper speeds, and less at lower speeds.

In my readings they said you can tune w/o a wideband, but its harder and takes more runs. Thats fine as they said dont make the full adjustment, take it in small incriments as it may be reading some residule(sp?) effects from some other area.