91 octane gas here is already $3.85 a gallon and rising.
We decided to do some test and tuning to see what can be done to reduce gas costs but still have fairly little loss in performance or damage due to ping
We had a perfect day as worse case weather in that temp was 85 degrees, winds of 19, gusting to 29 MPH.
Testruns were done at elevations of 3,600 to 4,000 feet.
Keep in mind the engine in our 1999 C5 has 11.3:1 compression so it would be more prone to engine ping/knock.
Also made use of is our water/methanol injection.
Starting with end results.
If we believed the forum hypes to have a perfect tune you must have the LTFTs at part throttle rich (negative values) in these test results shows that is bullshit.
On the left we have results were the LTFTs are rich and on the right side results we tuned to be about 10% leaner and you'll notice the injector duty cycle was reduced from 70% to 59% which means not only are injectors not working as hard but also flowing less gas but overall in in high engine loads the gas saver tune only lost about 15 HP at flywheel.
For daily driving then tuning to be leaner will save a lot of gas costs long term for very little loss of performance.
![[Linked Image]](http://teamzr1.com/mpg/mpg5.jpg)
Here is testing where on left we set for 5% leaner and then on right is for 10% leaner and notice there was no real performance loss at all at the required injector size needed is reduced.
![[Linked Image]](http://teamzr1.com/mpg/mpg3.jpg)
Here we can see the OBD-II realtime data where was see what little ping there was when the water/methanol injection came on the ping instantly went away and also due to the tune the attack and decay rate of ping is very quick.
![[Linked Image]](http://teamzr1.com/mpg/mpg.jpg)
Here we see even when there was ping that timing only decreased less then 3 degrees
![[Linked Image]](http://teamzr1.com/mpg/mpg2.jpg)
As the weather changes people also change the type of clothes they wear so its the same thing for your car is to have different tunes for the type of driving you'll be doing. With our PCM flash tool which is $200 less then a single user tuner tool you can switch tunes within less then 5 minutes of your time
In the end the city MPG went from 18 to 21 ( about a gain of 51 miles more per tank of gas)
and highway from 31 to 33