What's the purpose for the pilot injection?

Is the fuel ignited?

 

the purpose of the pilot injection is to get a flame started , pre hpcr had to inject all of the fuel at one time before top dead center and like gas it takes time to start the burn this is the diesel sound you hear on pre hpcr , the pre injection is at the same time as non hpcr after the flame is started the power injection sprays fuel into a flame , this is way more efficient. on 04.5 up there is a third pulse that is injected after all the work is done this pulse is wasted energy ,causes soot in the oil and kills mileage but has to be there to meet the new epa regs

 

^^^^Good post!!! The 3rd injection event is there for emissions, it creates enough extra heat to keep the cat happy.

 

I wish someone would come out with a box for "OFF ROAD USE ONLY" that would get ride of the dreaded 3rd injection event.

Does the 2006 and newer have 5 injection events?

 

If I remember correctly, I read that Marco tried, but couldnt get it to work right. (Dont hold me to that though)

 

Which is precisely why I got an 04.

The preinjection quiets the knock by spreading the shock of the ignition event over a longer period of time.

 

You are correct, Marco stated that when he managed to eliminate the 3rd event, they lost about 100hp!

 

Nope, does nothing for the CAT, it works without the 3rd event. The 3rd event is emissions AND power, it doesn't fire all the time, doesn't cause bad mileage.

Right foot and speed is till the ultimate fuel control.

I believe the 6.7's all have 5 injection events to meet the newer emissions requirements.

The predominant use for the multiple injection events is to to control NOX emissions by limiting the max temp of the combustion event. Spreading multiple burns across a wider range generates the same power at lower temps. By adding exhaust gasses it keeps the mixture lean enough to limit particulate emissions also by promoting a more complete combustion event.

 

So there's no way to get rid of the 3rd injection event? I disagree when you say it doesn't cause bad mileage. Every 04.5+ I have ever seen cannot touch the MPG numbers of any 03 or 04 before the 3rd injection event.

 

Thanks for clarifying the previous posts - I would just add that the pilot injection is responsible for the HPCR's quietness, and that the 3rd injection event is basically just in-cylinder EGR, which as a fringe benefit increases drive energy to spool the turbo more quickly.

Both the pilot injection and 3rd event are relatively too small, volume-wise, to negatively impact fuel economy.
Mileage increases significantly with aftermarket fueling software, such as Marco's, that changes the fuel timing - it's programmed to be retarded from the factory to help meet emissions standards.

 

Well, is entirely possible to drive a 600 series truck around all day and NEVER have the 3rd event activate. It still running on a pilot and main event and the mpg will probably be slightly worse. There are other software and hardware changes that were made to meet emissions, chiefly the in-cylinder EGR that contribute much more to mpg loss than the 3rd event. There is also the difference in power between the 2 that also contributes

There is really no way to get rid of the 3rd event and still maintain the power levels unless you fix the other changes also. The 3rd event is partly for emissions but it contributes to that power and TQ curve that is pretty flat out to redline.

A side benefit of the multiple events is also the quietness of the HPCR motor, along with some redesign of the block. It keeps the combustion temps and pressure down so you don't get all the noise of a single big bang. The NVH initiative definitely makes things a little easier on the ears and backside at times.

 

Great post guys!

 

Great info.

Hypothetically speaking now and for off highway use only. There has to be some way to modify these injection events to create better off road fuel economy at the expense of increased combustion pressure and Nox creation. Or is most of these emission issues brought on with the camshaft timing.

Anyone know what the differences are between an 02, 03, 04 or 05 camshafts on these engines.

I remember back in say 74 and later ford's used to retard the heck out of crank gear on gas 460 Cu in. engines. The trick was to use a crank gear out of a 1970 428 to get the power back. (for off road use only please)

 

yes the camshafts were modified to hold the exhaust valve closed for a longer period for the egr in cylinder operation you have to change cams helix 2 is what most are using i will talk to cummins Friday to see if there is any way to use ecm from a 04 on a 06 this would eliminate third injection pulse and bring it back into the 2nd if it could have been done by programing i think Marty would have figured it out