Is it possible to program my 4.8L V8 to run on 4 cylinders?

[mmagdelino]

I want to program my 2005 Yukon to run on 4 cylinders on the highway. I know the newer vehicles do this automatically by shutting down 2 cylinders at a time while cruising. If there is no way to program, can I manually switch off the injectors and what would the consequences be??

 

[Thecardoc]

In short, no it is not feasible to attempt to make your vehicle disable cylinders. There is much more to it than just shutting down the injection system. Vehicles that are engineered to do this today also disable the valve train, and modify the dampening of the engine mounts among other things.

 

[mattsooty]

Assuming the its a positive ignition engine & a V8, even if you found a way to switch off 2 or 4 of the cylinders, which you wont be able to do with the OEM ECU fitted, you would not gain much, if any fuel economy benefits.

This is because the main cost to BSFC, at part load, is due to pumping losses. The way that the usual Cylinder Deactivation systems work is by switching off the intake & exhaust vales to the non firing cylinders & opening the throttle further.

This reduces throttling losses and also pumping losses associated with gas exchange on the nonfired cylinders. Also, the fact that the intake & exhaust valves remain closed means that the losses due to compresing the air within those cylinders is, almost, gained back by the air behaving like a spring.

There is also some very clever torque matching which goes on within the ECU, using the spark & air paths during 4 & 8 cylinder switch over to make the transition transparent to the driver.

MS