# First regen



## BDCCruze (Jul 12, 2017)

Monitoring it like that may work for you, but for others that may read this there's no need to downshift to raise RPM. Just drive the car and it takes care of itself.

I've put almost 100k miles on mine and never once monitored it and changed my driving to match what it's doing, or had any other issues with DPF regen. I do drive freeway daily which helps tremendously, so if you are only driving short trips you need to take it out on the freeway once every tank of fuel for about 15 miles.


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## 15cruzediesel (Sep 30, 2019)

BDCCruze said:


> Monitoring it like that may work for you, but for others that may read this there's no need to downshift to raise RPM. Just drive the car and it takes care of itself.
> 
> I've put almost 100k miles on mine and never once monitored it and changed my driving to match what it's doing, or had any other issues with DPF regen. I do drive freeway daily which helps tremendously, so if you are only driving short trips you need to take it out on the freeway once every tank of fuel for about 15 miles.


That's awesome you've never had any issues in 100k and just driving it may work for you. But for me and a fair amount of others on this app we want more.

And based on the amount of manual regens done at the dealership and the reduced power posts that is enough for me to take precautions.

I am a gear head and want to understand what, how and why this car is doing what it is doing. Higher rpms help the regen process. Next time I might let it do it's own thing or I may turn it even higher rpms. I'm logging data for comparisons.

IMHO chevy screwed up making this car "seamless" and should have given the driver some feedback prior to and post a regen.

Thanks to Snipsey and the biscan app he has made educating diesel owners easy and at a reasonable price.

Far too many diesel owners don't fully understand how the emissions systems work, myself included. At the very least i want to be able to repair my own or if it is a warranty repair I will be able to go in with some intelligence to make sure they are doing what they are suppose to.


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## Rivergoer (Mar 30, 2017)

After monitoring nearly 100 Regens with a ScanGauge II, I found RPMs don’t make the Regen process go any faster because it’s based on EGT, not RPMs. 

Once EGT reaches 1100, Regen begins and will remain in effect till one of two changes:

1) Soot Mass reaches 3 (grams)
2) EGT falls below 1100F

If EGT falls below 1100F before Soot Mass is 3 grams, Regen will stop temporarily and wait till EGT returns to 1100F. 

At speeds over 40 mph, EGT will remain at the proper level and Regen will not be interrupted, nor will it proceed any faster at higher RPMs. At freeway speeds, dropping a gear to raise RPMs does not accelerate the time/miles required to complete Regen.

That said, RPMs CAN help maintain the proper EGT if a Regen happens to occur during City driving. I’ve used this technique when exiting the freeway during Regen, using lower gears to maintain higher RPMs (and therefore higher EGT) between stoplights/stop signs in order to keep the Regen active.

Not trying to discount anything said to this point...just trying to save a little diesel. 

I agree using an App or Scanguage device to monitor Regen is awesome from my experience. Knowing when the car is in Regen is very helpful to avoid parking it during an active Regen. I believe the less times Regen is interrupted the better with this car’s finicky emissions system.


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## BDCCruze (Jul 12, 2017)

@Rivergoer is spot on with the last paragraph. I have heard some people in other territories (say Australia) advise holding RPM's higher, at least on some of the older DPF systems. But yeah, that would only apply if you do not ever get out on the freeway. In the US Cruze the manual doesn't say anything about holding RPM's higher. It says if the system cannot correctly clean the DPF during normal driving, a warning message will display to maintain 30MPH until the warning light goes off. But in 3 years I've never seen that message.


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## 15cruzediesel (Sep 30, 2019)

Rivergoer said:


> After monitoring nearly 100 Regens with a ScanGauge II, I found RPMs don’t make the Regen process go any faster because it’s based on EGT, not RPMs.
> 
> Once EGT reaches 1100, Regen begins and will remain in effect till one of two changes:
> 
> ...


Wow. That is some great info!! Thanks. You witnessed more regens than my car has done!

I understand rpm's don't change the amount of time it stays in regen.

In my case I didn't mention it was a city regen and speed limit was 35 for about 80% of the regen and that is why I increased rpm's. I also decreased them at times and was monitoring the egt's through out the process.

Thanks for confirming the second reason a regen would pause. I was assuming that might happen but was unsure and had no clue at what temp It might occur.

Have you ever done a service regen? I have been searching for a procedure and have yet to find one. People talk about it but don't go into detail.

I guess you don't need to do one unless you get the message to get one done. I'm all for not doing one unless it would be necessary.


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## Rivergoer (Mar 30, 2017)

15cruzediesel said:


> Wow. That is some great info!! Thanks. You witnessed more regens than my car has done!
> 
> I understand rpm's don't change the amount of time it stays in regen.
> 
> ...


Sounds like you’ve done your homework, excellent!

Never had to do a service regen. I attribute that always monitoring regen and trying to never park the car during active regen. 

Only had to park during a regen a couple of times. The car automatically resumed regen after reaching operating temp during next drive cycle.

Another (personal) reason for not wanting to interrupt a regen cycle is the extra diesel consumption. Although pretty minimal, it does take extra diesel to get the DPF back up to 1100F in order to resume an interrupted regen cycle.

So keeping the regen going not only helps the emissions system keep functioning without issues, it saves a little fuel too.

Unfortunately a lot of 1st time diesel owners don’t even know what a regen is, nor were they even told about it at time of purchase (likely because the sales person didn’t know either). GM opted NOT to include any regen light or other indicators so as not to confuse the average drivers out there. 

I agree, some sort of additional DIC info regarding regen would’ve been a nice addition for those of us that like to know what our vehicle is doing at all times.


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## boraz (Aug 29, 2013)

BDCCruze said:


> @Rivergoer is spot on with the last paragraph. I have heard some people in other territories (say Australia) advise holding RPM's higher, at least on some of the older DPF systems. But yeah, that would only apply if you do not ever get out on the freeway. In the US Cruze the manual doesn't say anything about holding RPM's higher. It says if the system cannot correctly clean the DPF during normal driving, a warning message will display to maintain 30MPH until the warning light goes off. But in 3 years I've never seen that message.


bought the car in sept 2013, deleted it 2 mos ago

never saw a dpf message


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## boraz (Aug 29, 2013)

the info produced by apps/scanners can be troublesome though, especially when you dont know what the parameters SHOULD be

i member when errybody started getting scangauges and saw the transmission temps, ITS TOO HIGH I GOTTA INSTALL A COOLER CUZ MY 1994 CARS TRANS TEMP IS LOWER THAN THAT

the new info, to the ignorant, can do more damage than good.


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## Rivergoer (Mar 30, 2017)

boraz said:


> the info produced by apps/scanners can be troublesome though, especially when you dont know what the parameters SHOULD be
> 
> i member when errybody started getting scangauges and saw the transmission temps, ITS TOO HIGH I GOTTA INSTALL A COOLER CUZ MY 1994 CARS TRANS TEMP IS LOWER THAN THAT
> 
> the new info, to the ignorant, can do more damage than good.


Good point...Totally agreed. 

The CTD normal trans temps (210-225F) are definitely higher than what most older vehicles would be. Even my 1-Ton Dodge Ram only runs around 175F even climbing hills.


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## grs1961 (Oct 23, 2012)

BDCCruze said:


> @Rivergoer is spot on with the last paragraph. I have heard some people in other territories (say Australia) advise holding RPM's higher, at least on some of the older DPF systems.


Well, it's not just *people*, it's in the Owner's Handbook for the Australian Cruze, both those built in Korea and those built locally. (The current Cruze doesn't have a diesel option in Oz. Boo! Sucks!)

The Cruze diesels sold in markets other than NAmerica (and perhaps SAmerica??) have an indicator light telling the driver that there have been three failed attempts at a DPF regeneration, it is spelt out in the Handbook that you need to drive in a gear that keeps the RPMs above 2000 until the light goes out.

No one knows why GM-USA didn't activate the light in their diesel Cruze, but stupidity and incompetence probably cover it.


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## MP81 (Jul 20, 2015)

grs1961 said:


> No one knows why GM-USA didn't activate the light in their diesel Cruze, but stupidity and incompetence probably cover it.


Pretty much that - most people see a light on their cluster and assume the vehicle is about to explode.

Then again, people who buy diesels _usually_ are a bit more savvy when it comes to idiot lights.


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