Those are some pretty cool numbers. I'm very impressed.

 

I like the tune. I was impresed with my tune until I got Alvin's. Let me back up some. I think the ideal tranny control should be based on what is best for the person and needs more data to make that decision than throttle postion and vehicle speed. I feel that optimizing tranny shifting is one arena that has not been given as much attention by car manufacturers as they should. So, in my opinion, it is difficult to have the tranny fit every situation. I think if there is a table that satisifies everyone, Alvin's is closer than mine. My table is heavily biased toward highway driving when ironically most of my driving is city driving. I'm going to try to merge Alvin's and my tranny tables, if this is possible.

 

I didn't measure the gas flow directly. It was a mathematical calculation. I had to do some post processing of the data to get the posted numbers.

 

OBD2 stuff!! I wrote a few computer applications for this over the summer!

Did you use the stoichiometric MAF/14.7? You actually dont need data from the O2 sensors since the point of a computer controlled fuel system is to make sure 14.7 = A/F where A = air volume from MAF and F = fuel volume. The engine will automatically use the O2 data to control rich and lean conditions..all you care about for fuel flow is the MAF sensor. But the O2 sensors do make a difference. They need to be heated to 600 degrees in order to work so thats why when you start up your engine when its cold it sounds like its got a supercharger for a little bit because its bypassing the O2 data and running very rich until those sensors get heated up. The trick here that you showed is how the playing with long and short term fuel trim levels..aka cruise and acceleration trim rates. This is also why you should do all engine work and then get a PCM tune because lets say you put a K&N and exhaust system on, and get a HP boost from it. The extra HP will change your fuel usage and the engine will think it is outta whack. It will start playing with the fuel trim levels to basically de-tune itself until it sees the numbers it expects to see.
But you did a nice experiment with your numbers to actually show what these little computers are doing in our engines!!

 

Yes and no. I measured fuel consumption in two ways. One was with the MAF and you want to monitor total airflow g/s or lb/min (not cylinder air mass even though they have the same units). In order to do this, all the Ltrims need to be learned to make sure you are running at 14.7:1 A/F and the MAF needs calibrated (it can't have and inaccurate peaks or valleys in its response). For relative fuel testing you don't need to divide by 14.7 because it's just relative, but if you want the absolute consumption you need the 14.7.

The another way I used is based on fuel pressure, MAP (manifold absolute pressure), and injector pulse width. The fuel presure and MAP give you the delta pressure across the injectors that let you calculate the flow based on injector on time.

 

Interesting...did you get fuel pressure from the OBD port? I could never seem to get the code right for it and figured the sensor wasnt on the network.

 

Nope.

 

That is a distinct possiblility....[sm=happybounce.gif]

 

I received mine today and installed it. Instead of taking an hour like last time (because it was the first time), it only took me 15 minutes to swap them out. Piece of cake! It started right up without a problem. I'm running 93 octane and that's what it's tuned for.

It will be interesting to see what the manual transmission results are. I'm going to read all this technical data you guys wrote about and ask some questions, because I really want to learn about this stuff.

I'm taking about 100 mile trip tonight, so that should be plenty to feel if there is a difference. I will post later (LATE) tonight and let you guys know.

 

In one of my more technical engine theory classes I learned that power is equal to pressure in the cylinder (atmospheric pressure at WOT on a non pressurised engine) times the length of stroke times the area of the piston times the number of times per minute, or number of cylinders; or simply: POWER=PLAN. Also there is a specific fuel consumption for a given power output within a specific amount of time, figured: SFC= lbs. fuel/bhp/hour, where SFC is the specific fuel consumption, which equals the number of pounds of fuel consumed divided by the brake horse power divided by one hour. It would seem to me that all you would need to do is determine the difference in manifold pressure from an idle to WOT. Then, based on standard atmospheric conditions of 59F deg and a barrometric pressure of 29.92" hg @ sea level, you could determine any power setting and fuel consumption between the minimum manifold pressure at an idle all the way to maximum manifold pressure at max RPM.

In a basic aerodynamics class I learned about coefficient of drag. Coefficientof drag is equal to drag divided by dynamic pressure times area, or: Cd=D/q*A.

So it would be possible to find the coefficient of drag for the vehicle, and determine how much power is required to maintain a given speed. Then take this drag information and determine what power setting, or throttle position, would be required to maintain it, or to accelerate to it. When drag equals the power being produced, then you have a constant speed. Any more power than this will be used for acceleration. Using this power requirement as the BHP in the fuel consumption formula and figuring the lbs fuel used to produce that power from the air/fuel ratio will give you the specific fuel consumption for that power setting, and thus be able to figure the fuel consumption for that speed.

My question is, why couldn't you figure all of this stuff at your desk instead of driving around and trying different things to determine the best comprimise between fuel economy and power? Wouldn't it be chaper? I know nothing about programming a computer, so maybe I am missing something here. I do realise that on paper things would be figured for the specific conditions given, such as the standard atmosphere, but shouldn't the basic program of the PCM compensate for the differences of the actual conditions compared to the standard?