Haha,Im just a company guy so I'm stuck but I have been trying to pawn it off on the other drivers.....
I thought like you that they share the same system..
Well no W. Virgina but we are pulling heavier at 117000 gross.. 5mpg is about the fleet avg
I wondered if it was just a new engine break in thing with the consumption but noone has been really willing to say yay or nay.. Just to keep an eye on it.
The boost thing is weird in that even though the pressure drops on the gauge I dont notice that the power/rpms drops off to match... But you hear the change in turbo tone which is how I first noticed it.
Yea 15//gal a wk has been about the normal for me with past 2 trucks Ive driven.
New Paccar DEF and boosting concerns...
Discussion in 'Trucks [ Eighteen Wheelers ]' started by Agtrucker, Oct 27, 2018.
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Opens for me, but I cut and pasted best I could for Adobe Document.
Expected DEF Consumption and Calculations
If a customer has a concern that their truck is using too much DEF, the consumption can be calculated by using values found on the trip recorder. This article will guide you in calculating the total consumption based upon fuel usage.
While there is no spec for this, the maximum expected DEF consumption is 7% of fuel usage. Typically, the consumption will fall between 5-7% for MX engine-equipped trucks, however values of up to ~10% are considered acceptable. Extreme temperatures and operating conditions can require higher amounts of DEF to control NOx output.
1) You will need to first retrieve the trip recorder from the PMCI/PCI via DAVIE4. If this is your first time finding this, click here for instructions.
2) On the trip recorder, locate the values shown for ‘Trip DEF used’ and ‘Trip fuel used by engine and aftertreatment’.
3) Calculate the DEF consumption with the following formula:
Trip DEF used/Trip fuel used by engine and aftertreatment *100= DEF consumption as a percentage. 708.84/18,570.11 * 100= 3.8 %
4) If the calculated consumption is falling above or below this expected 5-7% range, excessive DEF consumption is most often caused by an SCR efficiency issue. This includes a faulty sensor, damaged SCR catalyst, or other failure in the engine and aftertreatment systems. DEF usage can also be significantly influenced by idle time, engine load factors, engine condition, average driving speed, terrain, and ambient temperature conditions. Perform preliminary diagnosis of any related fault codes and visual inspection of the DEF & SCR system to identify a possible root cause.
5) Note that if the DEF doser is leaking, it will not show up in the DEF consumption equation. The “Trip DEF used” value is the amount of DEF that the aftertreatment system has commanded the DEF doser to inject into the exhaust stream. The aftertreatment modules also do not have the capability to detect a leaking DEF doser.
6) Be aware that if the trip meter has not been reset recently, it will not properly reflect a recent DEF consumption concern. It may be necessary to reset the trip meter, have the customer operate the truck for a period of time, and review these values again at a later date.
7) If a root cause cannot be found, create or update your MX Engine Support case on SupportLink with your findings. The Engine Support Center will further investigate the operating conditions and data to determine if there is failure present.
PACCAR Engines Support Center | Last Edits: 11/30/2017Cat sdp, Oxbow, daf105paccar and 1 other person Thank this. -
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