Just received a newsletter from Cummins that in part states:

"There are actually three separate injections or “pulses” per cycle – the pilot injection pulse, the main combustion charge pulse, and the post injection pulse. Using three fuel pulses enables Cummins engineers to substantially reduce emissions of nitrogen oxides and hydrocarbons because it’s a much more efficient burn"


I have read a few posts where folks have questioned if a 3rd event occurs. According to the newsletter it does.

Now if we could just figure out how to turn it off (for testing purposes) to see if mileage is affected and if so by how much. Might be an interesting experiment.

Just a thought
Allen

 

Although, if the third injection event makes the burn more efficient like your quote says, wouldn't that mean the third injection event increases fuel economy? More effeicent = less fuel to produce the same power?

 

I don’t believe the third event increases efficiency, I believe it serves the other listed reason, to reduce emissions. Now I am not suggesting that we modify our trucks to make them illegal but it would be interesting to see the impact to fuel mileage. Most likely, the cat would have to be removed (again I am not suggesting removing the cat and violating federal emissions standards) as the general thought is that the third event is wasted fuel just to keep exhaust gas temp high enough to keep the cat lit-off (functioning).

I am just curious to see what the reduced emissions is costing in fuel consumption, if it costs anything at all?

 

Hey Blown,

So do you suppose this could be one of those situations where Curiosity Kills The CAT?
yuk yuk yuk

 

But seriously, I would bet that if the third event were to be turned off with the Kat in-place it would eventually die (become plugged?)

 

Or if the exhaust was insulated to minimize heat loss, could the exhaust temps be kept high enough to burn the crud out of the cat and not waste fuel ?

 

For the ones that do not have a Kat, it would a nice increase in fuel mileage.

 

So, can we get our hands on the programming of the injectors to discard the third event? I imagine this would be done at the ECU, but you should be able to filter the third event inline with the injectors too ... the signal to them can't be much more than 0-1-0. Anyone, Bueller?

 

Nope not hard at all, except for the fact your forgetting frequency and duration. Obviously the 3rd injection event would not be the same putzing around town at 1,200rpm as opposed to 2,400rpm going up a grade. Then you might filter a good pulse out, ouch. It needs to be done in the ECU, but I have a feeling that soon enough someone will figure it out and release it to the GP.

 

Doesn't the third event stop when exhaust temps gets hot enough to keep the kitty clean and wouldn't that be why the fuel MPG is so poor around town but if we head down the highway at 65 some of the 3rd generations can get 20 MPG or better. I guess my question is if this is correct is thier a way to fool the sensor and have it turn off the 3rd event for us? Also if this is correct won't we be seeing a lot worse MPG this winter and what is the reason for the first event it doesn't make sense that would be for emisions does it? Maybe just mounting the sensor some place that heats up faster would help or maybe I am just up to late.

 

There is no sensor for it, nor is there a pyro to control it. The ecu has a table for it computed from all stock sensors. The first injector event is why our engines are called "Echo" engines, it makes it quieter. Small pulse, main pulse, 3rd injector event.

 

Thanks John Am I correct In my thinking that the 3rd event shuts off when the engine warms up or is this wrong also. I wasn't thinking a pyro by the kitty I was thinking the water temp sensor in block could be fooled some how. I was hoping maybe thier is a seperate wire from the sensor to the ECM we could increase voltage to and not mess up our dash readings. Our maybe I just got up to early , thanks for your reply.

 

Well, it's not water temp sensor because that controls alot of thing, it's no one-set sensor, just how the ECU is setup to make the truck run and accelerate, it's setup for 3rd injection event. It wasn't an afterthought put in, the whole system was DESIGNED for the third injection event, and a computer reflash would be neccessary to remove it.

 

I didn't think the 03-04 engines had the third injection...hence no CAT. I thought the third injection was an 04.5-up 600/610 addition to meet ever increasing Tier 3 regs.

Chris

 

Chris,

That is my understanding as well, 3rd event only on 04.5 and newer. The Cummins newsleter I copied the first post from was talking about the later trucks.

Sure would like to see this put to the test.