Alright let me set the mood.
This comment in the other thread:
Originally Posted by 95naSTA
Bill, I'd have to see your fuel trims to believe it.
Wasn't ment as a jab at Bill or implying that he is wrong/lying.
To me it just seems pretty amazing.
The internet is a wonderful place to have comments taken the wrong way.
In my mind there is a possibility that it can work.
But there would only be a select few applications where it would. I trust Bill enough to assume he fits this criteria.
So heres whats going on in my head:
Bill'* general situation from what I've read:
(expecting some correction as I probably don't know everything)
LIM porting done, gen 3 blower swap, and flow matched injectors.
From these mods the engine should be flowing more at all times and more importantly each cylinder should be getting the same amount of air and fuel.
PEMs and some exhaust work.
Also, making the engine flow more air in general.
Jet stage 2 chip
Slightly more timing? higher shifts, and modified fueling. This could have the potential to yeild more KR if my ASSumption about the timing is correct. But the modified fueling could also help in meeting the demands of the engine flowing more.
Now on the the adjustible FPR.
I'm relating it to my adjustible trans modulator since there both vacuum controled diaphragms.
I've noticed that if I tighten the center pin too much, the trans will bang into gear but it will shift hard at WOT. When I loosen it, the banging into gear will stop but the WOT shifts will be softer. I have also seen cut away views of diaphragms so I understand how they work mechanically. So, thats where I'm coming from in my understanding.
Now with Bills setup I'm assuming that it flows more in general but I would also assume that it flows significantly more at WOT. With that said I would think that would be much more fuel needed up top as well.
So, Now back to the adjustible FPR. If your increasing the fuel rail pressure at WOT, the pressure must also be raised at idle. At least slightly. This would initially create a rich condition.
But.... Wait Wait Wait!!!
I also understand how these comupters manage the fuel. It has an initial fuel curve (in this case it'* Jet'*)for any given condition. These conditions are a combination of many sensor outputs such as MAF, MAP, Crank Sensor, IAT, etc.
Control feedback for the fueling is taken from the O2 once the car warms up. And Integrators (INT) are generated. INTs will over time adjust the Block Learn Memory which is a modification of the original fuel curve. The initial BLM will be at 128.
When fully learned, if the BLM is higher than 128 at a certian situation more fuel was added. And if it is lower, then the car was originally running rich at that certian situation.
Although the computer can adjust it is always best the have your BLMs as close to 128 as possible. From what I understand the pcm is designed to work efficiently at or close to that condition. So, the further you move away from BLMs of 128, the less efficient your fueling becomes.
Back to increasing the fuel pressure at WOT and also having an increase at Idle. The computer can adjust for a rich condition creaded by the increased fuel pressure at idle over time but unless you have the right mix of conditions your BLMs are going to be off somewhere. And if they are too far off the fueling won't be as efficient.
Now another point that Bill has made is the higher pressure (to a point) leading to better fuel atomization especially at WOT. With better fuel atomization there is less fuel wasted since it burns easier. That would also lead to less overall fuel. This also means that, up top, it'* easier to get the fuel needed. And the change in pressure increase dosen't have to be as drastic.
So, Bill I do understand cetian things that could make it work but the window of opportunity for having this work seems to be narrow to me.
I'm not trying to call you out Bill but could you post your highest and lowest BLMs after you have considered the computer to have learned the setup? Not a recording since you cant do that just the #* you have observed.
And lastly about the AFC, specifically the 2.0. IMO this is a great tool. I have been using it for over a year and a half now so I have plenty of experience with it. I recognize it'* draw backs and limitations and also realize that it isn't the end all solution for fueling but it has been working great for me. With this tool and changes within +- 8% of the current fuel table I am able to maintain very good Long Term Fuel Trims (BLMs). This is not just for one condition either. When cruising on the highway, accelerating, etc., the LT Fuel Trims do not stray far from 128. Ultimately, I will have the fueling programed to eliminate the use of the AFC. Then the curve will then not be limited to 12 linear segments associated with maf frequency but an actual curve.
Another advantage to programing out the AFC is different conditions will be suited better that have the same MAF flow rate. For instance you could be cruising and the MAF sensor will be picking up 40 gm/sec and sure enough at some point during acceleration you will also be flowing the same amount. Adjusting with the AFC changes both conditions while you may have only needed to adjust one. THAT is the major draw back of the tool.
But even so, from my experience with it on my car, I am able to suceed in getting my fuel trims to be correct.
I posted this topic to discuss both topics in the title. I'm not trying to stir up any pissing contests or 'one uping'. This is a great oppurtunity to learn more about the subjects at hand from one another. So... CONSTRUCTIVE comments are more than welcome.