GM,Chrysler,Honda all have Variable Displacement Engine Systems where they cut out 1/2 of the cylinders under lite load - That is: idle,coasting,braking and other times when full power is not required.

Claims of 10 % MPG improvement.

I have been experimenting with my 2003 V-10 Excursion. I pulled the Injector Connectors on the Passenger side. Starts,Idles,drove around the neighborhood fine. No Knocks,"Check Engine Light".

I am proceeding to design a vacuum controlled relay to drop the 5 cylinders under lite load (High Vacuum).

Can anyone see where this scheme would cause engine damage???

The GM,etc also disable the valve lifters on the cut off cylinders.

 

I can't believe that having the injectors unplugged didn't throw a code. I guess there is no feedback to the computer from them. Do these motors have a limp mode? If they did and you could get it to kick to limp at high vacumm it might what ya want but not sure on if it would wanna stay in 'limp' mode.

 

I think the Triton line of engines have a "limp" mode where 1/2 the cylinders fire if there is a coolant leak and the engine becomes too hot. I wonder if you can tap into that sub-system in the computer somehow?

 

I would check the firing order of the cylinders to decide which to cut out, and keep things balanced.

I assume that as long as the lubrication system (jets, orfices) are not affected there should be no issues.

 

I am looking into the "limp" mode. My engine has a "fail-safe cooling" mode that is triggered by peaking out the engine head temperature (6G004). This mode implements alternating cylinders - using the cut out cylinder blowing air to help cool the engine. I need to look at the total algorithm _ One thing it does is shut off the AC, I don't know about timing,etc.