Are there any? I've searched, but haven't found any true proof.
Dude that is really awesome that y'all did that, and the extensive research you did on your own!!In all seriousness, the only thing (other than your foot) that can help, is a specific tune designed for high fuel economy is probably the most effective.
A few years back, I was involved with group of hot rodders and we had "disassembled" the programming of the ECM (computer). It was OBD 1. We relayed a lot of the info to a company who developed a "user friendly" computer software program where we could alter the fuel maps, spark maps plus a number other items.
One interesting item we found were "Lean AF Ratio" and "Lean Spark" Maps that the manufacturer had developed the code, but disabled. After a little "bit twiddling" we were able to invoke it. In spite of all the warnings from the Debby Downers, I played with the "Lean AF" and "Lean Spark" on how they worked and if they actually did increase fuel economy. I found that I was able to lean out the AF Ratio from the normal 14.7 Stoich to 18:1.
Unfortunately, the throttle response became really spoungy and lost a lot of throttle response. At first I thought the Lean Spark was designed to decrease the Spark Advance so I wouldn't blow a hole in my pistons when running such a lean AF Ratio. But, I found quite the opposite, I found advance the spark so I was almost at 45* that restored the throttle response (there was a built in offset that kept the rotor cross-firing to the next electrode... but 45* was the limit).
The trick to all this was keeping the EGR valve working which introduce inert exhaust gas into the cylinder. I effectively reduced my cylinder filling by approximately 35% ... like a "gaseous version of cylinder deactivation".
Results, I did dramatically increase my fuel economy by 25-30%. I tested it numerous times driving a very long stretch of highway (to visit family) with the original programming and my modified programming, setting my cruise control to the same speed. Best of all, I was able to deactivate it by simply increasing my engine load from the MAP Sensor. Go up a hill or stomp on the throttle and the vehicle would immediatley return to normal operation with immediate throttle response.
So, I am absolutely convinced that a well designed tune from a tuner who spent a great deal of time testing it, can produce a good tune that can save you money .... AND not cost you any performance when you stomp on it... (but it will kill your gas mileage as stated earlier).
PS: Before anyone asks "If the manufacturer had this code in the original programming, why didn't they activate it themselve?" The only answer we could think of (since we could never find anyone who worked on the original code) is that the super lean condition probably increased some polutant ... NOx most likely. And it wouldn't get past emission testings which became more and more stringent with dyno testing in some states & provinces.
Oh yeah, the other effective ways of increasing gas mileage we found were increasing the aerodynamics of your vehicle and putting your vehicle on a severe diet.
Dude that is really awesome that y'all did that, and the extensive research you did on your own!!
In such a lean state what did your EGT, oil and water temps look like?
Have you looked at SCT's Avantage III Pro Racer software?In all honesty, I would LOVE to just find someone who sells the software to access the various Fuel, Spark and boost Maps in our PCM. I know of some for other manufacturers (mostly OBD 1 for another manufacturer) and a few for OBD II Systems. I am sure these PCMs are "light years" ahead of the stuff I was playing ... and I was amazed on what I was able to control and make that ECM do.
However, once we able to "dig inside", we also started to look inside some of the "aftermarket chips". It was very sad, most were absolute rip offs.
That would be so COOL! :BIG THUMBS UP:ok i might have misled you it seems the tweecer only supports up to 2004 so i will talk to my buddy this weekend and get some ideas on how to modify perameters on the ECM's of today
he might know something else to look at