This page is about getting the best fuel economy.

If you have some experience or know-how please let us know.

Injector divider

Admittedly, injector divider was never ment to be changed with running engine.

Test cars:

Volvo turbo 4 cyl. Sequential

Audi s2 5 cyl. Sequential

We did test the too cars by setting the injector settings to divider by 2 and it is actually working pretty good.

This function is only for cruising when the car is up to speed cores lack of power.

We need a strategy how to improve this function.

Did a lot of testing on this with a 5 cylinder Audi - 1.2.16. Program B is the same as A, except that the injector divider is 2. Currently, I activate the function with a switch.

Car stutters violently when I swap in low gears, but from 90-140 km/h in 5th and 6th, it actually works.

I wanted the car to switch back and forth on its own, but I end up getting into an endless loop.

Example: I want the car to turn off every other injection (change to program B) between 2500 and 4000 rpm. Changing one way is easy, but the problem is that I can't get it to change back from B to A because that would need two windows, i.e. idle to 2500 AND 4000 to 7000.

Would it be possible to move the output parameters away from the part that is specific to A and B, so that it would swap back as soon as the revs are NOT 2500 to 4000?

Or possibly thange the divider in response to outer conditions, so I wouldn't have to swap programs?

Another neat feature would be to let the output react on throttle movement. If the throttle is moved quickly, the program should always go back to A and run on all cylinders.

Cool thing is that the same cylinders aren't passive throughout (like on late model Audis that always switch off the same cylinders). It actually seems to turn cylinder 1 of every other time, making the sequence 12453124531 => 1X4X3X2X5X1

Won't run as smoothly as on the new cars with variable valves, but it works. Must run even better on a 6 or 8 cylinder car.

I am hoping to save 3-4 % fuel this way, reaching 800 km on one tank :-). As long as the car runs this way, consumption is 50-60 %. Not exactly 50 %, though, because you open the throttle a bit more (not sure about that) in response to the lack of power. Can't measure that well because lambda gets messed up from the fresh air that is pumped through by the "empty" cylinders.


Fuel Savings

eg. by Leaner mixture

Some methods can improve fuel economy, often by allowing leaner mixture (or allow engine built to higher compression):

Less shaft power:

The average (1.6 - 3 liter) engine is just not optimal for cruising

Volvo 960 B230FT. 18 dec. 2013

I tried the table config switch, and fuel divider set to 2.

When running 3000rpm part throttle cutting out 2 cylinders of 4 is to much. It is difficult to keep up speed, but cutting 1 cylinder might work fine.

See log:


It could be interesting to try, if I just could cut 1 injector event at every 8 ignition event (or 12 or 16).

This is only when at part throttle, of course.