DPF Fueling Location

[RSchwarzli]

Dad and I are at it again! He has one theory, I have another regarding the DPF Fueling.



This is are question:



When the regen mode is active, at what point in the exhaust system is the fuel injected into the system? Is the extra fuel injected into the cylinder on the exhaust stroke, or is it injected right into the Self Bake Oven??



This all started because he was under the truck and saw fuel lines going into the DPF. To my memory, there is no fuel lines down there (what they are, I don't know. Have not been under there yet). I was under the impression that it was on the exhaust stroke, hence the reason the oil gets contaminated with fuel quicker.



So, who is right?? Is dad of his rocking chair, or do I need to be more respectful to my elders??



Thanks!



Robert

 

[Drdorian]

Dad and that rocking chair again... . the lines going back to the DPF are pressure lines, if you follow those they will go to rubber tubes which are attached to a sensor that is attached to the transmission, the sensor is the delta pressure sensor. Fuel is injected in-cylinder on the exhaust stroke.

 

[RSchwarzli]

That makes more sence.

Now regarding the pressure lines, what do they exactly do??? Delta whooey? Is this basically the back pressure sender to notify the emittions system that the ez bake needs to activate? If so, why do the lines lead to the trans?? What does that have to do with fuel??



Thanks!



Robert

 

[AH64ID]

Now on the bigger trucks with a DPF they do get raw fuel... .

The pressure lines measure the difference (delta) in the inlet and outlet of the DPF to tell the ECU how plugged it is.

 

[grasmo]

I think the sensor is located on the transmission because it was just a convenient location. That particular location was dictated by the length of metal tubing required to disapate the heat coming up from the exhaust pipe.

 

[Tinman]

Is fuel not injected in the normal intake stroke during regen? Is the fuel in the exhaust stroke burned in the cylinder? Does this process temporarily make the engine a 2 stroke? Interesting and I'm so glad I don't have it.

 

[RSchwarzli]

Fuel in injected both cycles. Normal intake to burn in cylindar, and on the exhaust to burn in the DPF. That is the only place the exhaust stroke fuel is burned, hence the reason for the bad fuel economy as you are getting nothing for it (in regards to forward momentum).



At least that is the way I understand it.



Robert

 

[AH64ID]

Fuel in injected both cycles. Normal intake to burn in cylindar, and on the exhaust to burn in the DPF. That is the only place the exhaust stroke fuel is burned, hence the reason for the bad fuel economy as you are getting nothing for it (in regards to forward momentum).



At least that is the way I understand it.



Robert

Right... injected on the compression stroke, for normal operation. And on the exhaust stroke, with the exhaust valve open, to run raw fuel to the DPF.



It does not make it a 2 stroke since the fuel on the exhaust stroke never gets compressed and doesn't combust.

 

[RSchwarzli]

Thanks guys! I think our bickering is over. For now!



Robert