Yes you can “passively” regen when working the truck since the EGT is higher and can reduce the soot load. Regens are not just based on soot load though. It’s possible you haven’t gone through a regen yet even though it should happen around 800 miles. I think @Piper One can chime in here. I believe he recently somehow skipped the normal parameters of a regen too by a weird combination of factors.

 

Pulling will reduce soot but the truck will still regen at 807 miles max.

I did have a regen go 1400 miles but the truck had visited the dealer and had new ECM and BCM files loaded (I added high idle RPO UF3) and the truck basically forgot where it was mile wise and started at zero, even though it was 600 miles into a cycle. I don't know how, but I'd LOVE to figure out how to do this regularly.

 

Yup 807mi is the limit. I would like to know how to fake it out as well. Mine usually regens right at 807mi at about 30% soot load. Have 25,000mi on truck now so not many miles and the that will probably change as the DPF ash load goes up. Has waaay more capacity than to just arbitrarily start a regen because of 807mi. Stupid waste of fuel. For people doing highway miles or towing its pretty easy to keep soot levels low.

 

I am running car scanner app with a Bluetooth connector. I towed 45 mi in about an hour yesterday. When I left my soot was at 31. When I got here the soot level was at 8. According to the scanner it has been 836 mi since my last regen.
My question is will pulling reduce soot levels or did the scanner miss a regen and not reliable in that manner? 4000 miles on the truck.

Were you monitoring if you were in an active regen or not? The “counter” doesn’t reset till you finish a regen so maybe you were just in the midst of one and it wasn’t complete yet.

My understanding is the scanner can’t “miss” a regen. Those values are stored in the ECM (I’m guessing) and your scanner is just reading the values reported.

 

I am monitoring Regen status as well. Thought maybe I was monitoring the wrong one, not sure what they are called.

 

I am running car scanner app with a Bluetooth connector. I towed 45 mi in about an hour yesterday. When I left my soot was at 31. When I got here the soot level was at 8. According to the scanner it has been 836 mi since my last regen.
My question is will pulling reduce soot levels or did the scanner miss a regen and not reliable in that manner? 4000 miles on the truck.

Sounds like a regen is occurring. It will activate around 800ish miles or 1 tank of fuel used or soot level at 100% whichever of those occurs first and take about 20ish to 30ish miles to complete on a l5p

 

you do not want to go longer between regens. the purpose of more frequent regens is to prevent dpf from clogging up and having to be replaced for 10k$...

 

True, but I think the question is if you are entering a regen at 30-50% soot load because you are towing or driving a lot of highway miles, does that really prolong the system's life? I believe someone else on here said that the power strokes and Cummins do regens at a much shorter interval mileage-wise. Not sure how true that is, but it does make me wonder what is better: a longer time between regens however the regen takes longer to complete? Or shorter distance between regens and, thus, most likely shorter time for the regen to complete.

My gut instinct is that the temperatures the DPF is exposed to during a regen is probably not the best for it. If that is the case it is interesting that we are forced to regen at 807 miles regardless of soot load. I understand needing multiple factors to ensure the system is harder to cheat but it would make sense that if your soot load is only at 30-50% when the other parameters hit you could wait longer.

 

I think the dpf itself would rust out before heat would hurt the innards

 

That’s a fair point but isn’t the filter itself made from ceramic materials and should be relatively resistant to rust and corrosion? I would assume that the temperature the DPF gets to is also well below the threshold for damage - or at least I would hope they thought that through.

At this point I’m just curious how the engineers came up with the parameters they did

 

GM says there are 4 things that can cause regen to initiate:



How Regeneration Should Occur

The DPF traps the soot generated as a part of the normal operation of a diesel engine so that it is not sent into the environment. The process of regeneration enables the vehicle to clean the filter so it can trap more soot. Factors that determine when the ECM will try to perform a regeneration include:

• After approximately 36 gallons (136 L) of fuel used since the last regeneration.
• A maximum distance of 800 miles (1287 km) have been traveled since the last regeneration.
• A pre-determined number of engine hours since the last regeneration.
• A calculated or measured soot mass of 100% in the particulate filter.

When any of the above criteria are met, the ECM will perform a regeneration as soon as all the correct conditions are met. If the ECM cannot perform a regeneration, the ECM will only look at the soot mass to determine to display the Continue Driving DIC message or to set DTC P2463.

 

I've watched the soot load go down, while the truck was not in regen.
Truck was towing, and running at freeway speed -- so exhaust temps higher than what it runs during it's usual day to day driver duties.

I've also tracked the regen intervals for this truck.
The 'long' intervals were always when it was working harder. (Higher than usual speeds, towing, or both)

 

Even unloaded if I'm getting after it on the highway "on cruise" going fast but not going WOT my soot levels will drop when that boost stays higher and consistent

 

Do you display / watch the exhaust temp?

 

my understanding of it is:

the soot% is not a measure of actual soot in the dpf filter it is an estimate made from pressure sensor when sensor reads enough back pressure the truck computer thinks the dpf has enough soot in it to warrant a regen. so it kicks one off.

the fuel use engine hours and mileage triggers are there all as backups to ensure that regeneration are done in case of false sensor readings.

I would guess that for pickup truck diesels which have non serviceable dpf filters they add these triggers and numerous regens to prevent clogging.

personally I would prefer a serviceable filter and I wish there was one for the 2020+ l5p
I would buy that system and switch to it when mine finally goes.

 

LML displayed soot level as 'number of grams'
Those with monitors reported regen would start at about 42 grams.

Beginning with L5P, they number is called % soot and trigger at 100%
They also added a 'soot sensor'. (see diagram)

Regen at 100%
Keep driving at 115%
'Service regen required' fault will set at an 'undisclosed' level above that.


More regen info:

When to Perform a Diesel Service Regeneration – TechLink

When to Perform a Diesel Service Regeneration
December 31, 2017
A change was implemented recently in the values of the Diesel Particulate Filter (DPF) Soot Accumulation parameter displayed in GDS 2. On all 2016-2018 Colorado and Canyon models and 2017-2018 Express and Savana models equipped with the 2.8L Duramax diesel engine (RPO LWN) (Fig. 6, B); 2017-2018 Silverado and Sierra models equipped with the 6.6L Duramax diesel engine (RPO L5P) (Fig. 6, C); and 2017-2018 Cruze models equipped with the 1.6L diesel engine (RPO LH7) (Fig. 6, A), the DPF Soot Accumulation is measured in percent instead of grams.

Fig. 6

On these vehicles, the Engine Control Module (ECM) will not try to perform a regeneration until the DPF Soot Accumulation increases to approximately 100%. If the DPF Soot Accumulation increases to 115% and the system has not been able to regenerate due to driving conditions, a Continue Driving message will be displayed on the Driver Information Center (DIC). If the DPF Soot Accumulation increases above a calibrated percentage (based on diesel engine application), DTC P2463 (Diesel Particulate Filter Soot Accumulation) will set and a Service Regeneration will be required to clean the DPF.

As part of the emissions system, the DPF system includes an Exhaust Particulate Sensor (Fig. 7, A), an Exhaust Temperature Sensor (position 4) (Fig. 7, B), and the Diesel Particulate Filter (Fig. 7, C).

Fig. 7

Service Regeneration vs. Regeneration Enable and Drive Cycle

A Service Regeneration is designed to lower the soot accumulation in the DPF in a very controlled way. It is not as effective as a Regeneration Enable followed by driving the vehicle. A Service Regeneration should only be performed if the procedure is called out in the appropriate Service Information.

TIP: During a service regeneration, the vehicle will need to be parked outside the facility and away from nearby objects, such as other vehicles and buildings, due to the elevated exhaust gas temperature at the tail pipe during regeneration. The service regeneration can be terminated by applying the brake pedal, commanding service regeneration OFF using the scan tool, or disconnecting the scan tool from the vehicle.

If a vehicle has less than 70% DPF Soot Accumulation, do not perform a Service Regeneration unless instructed to by the Service Information. If there is a concern about the DPF Soot Accumulation, perform a Regeneration Enable and return the vehicle to the customer for a drive cycle.

TIP: If a vehicle with less than 500 miles (800 km) displays a Continue Driving message on the DIC, refer to #PIP5468 and Bulletin #10-06-05-002.

Converting Engine Hours to Mileage (km)

Fore vehicles that spend a lot of time idling, use the following formula to aid in determining the equivalent mileage (kilometers) for vehicle maintenance. This formula applies to diesel as well as gasoline engines.

1. Check and record the total engine hours on the DIC.
2. Multiply this time by 33 miles or 53 km.
3. The result should be close to the mileage on the odometer.

For example, if a vehicle has 626.9 engine hours and 7,269 miles (11,698 km) on the odometer, the engine run time would equal about 20,688 miles (33,226 km).

626.9 x 33 miles = 20,688
626.9 x 53 km = 33,226

This vehicle would be considered a vehicle that idles a lot, which may be useful information when diagnosing any issues.

The engine hours formula should be used to aid in engine diagnosis only. It should not be used to determine any warranty claims.