Hi Guys, I wonder if any of you CAT boffins on here could shed light on this fuel saving idea. Recently I carried out an experiment on one of our CAT 785 trucks regarding methods of fuel saving by setting down the "air fuel ratio" on the engine ECM, this I did by setting it down one value (which equals -25 on the ET screen) then I took down ECM hours and monitored it for a week and then set it back again to the normal parameter. During this experiment we had no overheating or power loss and no operator complaints.I found by doing this we burnt 5 gallons (22.5 liters) of fuel less per hour. Across our fleet this could be a massive saving but would wish to know that before carrying such a procedure what would the long term effects be? Look forward to your comments. Pete.
Did you notice that the reaction of the engine under load has reduced..? The A-F ratio control adjusts from -25 to +25. Its major purpose is to stop black smoking when the turbo first spins up and the injection system reaches full fuel before the turbo gets chance to develop full bost pressure. If the first move that a loaded truck makes from under the loading tool is either downhill or at worst level (plus if you're not seriously overloading) you should see no difference at all in outright performance, just that the engine will be a little slower getting to full performance from idle.
Hi Nige, Thanks for your reply! It looks a bit like the swings and roundabouts story being "if we save on fuel we will lose out on production" i.e. slower cycle times in the pit! Cheers, Bucknobs.
I'd recommend that you take a look at your cycle times and see what effect (if anything) knocking off a bit of the engine response has. We haul a lot of loaded downhill so winding back the A/F ratio does absolutely nothing negative on our fleet.
Hi Nige, Thanks for your thoughts on this, what I will do is change the A/F parameter on two trucks after checking their present burn rates then monitor the changed ones over a period of time including their new cycle times. Besides keeping a check on idling times spent running in neutral (which amounts to poor utilisation of trucks) have you any other ideas on fuel saving? Cheers, Bucknobs.