# Diesel City Driving - regens



## obermd (Mar 3, 2012)

I think 35 miles is sufficient to do proper regens.


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## Roadburner440 (Dec 29, 2013)

His commute is about to go from 35 miles to 2. So his commute was sufficient. To be honest with you I don't think anyone knows. 2 miles wouldn't be enough to get the engine up to normal operating temperature which is required for a regen though. So I would say this is probably not going to go well with the emissions system. As long as you have highway drives to the store, or elsewhere every now and again I would think that would help. GM has issued an ECM update to help city drivers with regens by apparently upping the EGT and duration of the regen, but I am not sure of the software # or what to ask your dealer for to get it.


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## boraz (Aug 29, 2013)

obermd said:


> I think 35 miles is sufficient to do proper regens.


and if the regen began 20 miles into the commute?


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## jblackburn (Apr 14, 2012)

boraz said:


> and if the regen began 20 miles into the commute?


How many miles/minutes does a regen typically take?


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## obermd (Mar 3, 2012)

boraz said:


> and if the regen began 20 miles into the commute?


And if it begins 99 miles into a 100 mile drive...? You have the same issue. I would hope the computer would record the incomplete regen and start it as soon as the engine reaches operating temperature on the next drive.


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## plasticplant (Mar 26, 2013)

Might be best to just bike it and save the CTD for the longer trips.


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## Roadburner440 (Dec 29, 2013)

If you interupt the car during a regen it will attempt it on every subsequent start to my understanding of how it works.. You get in to trouble territory though when it needs a regen and you do no drive it long enough above 35mph for enough cycles. It eventually builds up to whatever the magical soot number is to drop it down in to limp mode and a forced dealership visit for a manual regen. A 2 mile trip would not allow that to occur though so once you entered that cycle it would just repeat until the car mandated you take it in for service.


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## Sperry (Aug 3, 2013)

A normal regen is about 15 minutes at highway speeds so I would think it will at least that long in the city..


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## oilburner (Jun 13, 2013)

Roadburner440 said:


> If you interupt the car during a regen it will attempt it on every subsequent start to my understanding of how it works.. You get in to trouble territory though when it needs a regen and you do no drive it long enough above 35mph for enough cycles. It eventually builds up to whatever the magical soot number is to drop it down in to limp mode and a forced dealership visit for a manual regen. A 2 mile trip would not allow that to occur though so once you entered that cycle it would just repeat until the car mandated you take it in for service.


correct


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## Aussie (Sep 16, 2012)

On my Australian diesel if the car needs a regen a light comes on in the instruments and you need to take it for a drive keeping the engine above 2,000rpm. I have been doing mostly City driving for over 2 years and the light has only come on once and that was in the first 6 weeks and before the engine lost it's tightness.

By the way I had to keep driving until the warning light went out, took about 10 minutes.


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## thmike (Sep 1, 2014)

I only have stopping 2200 miles on my td amd I've never seen a keep driving light yet. My drive to work is around 2 miles also. I'm also pretty hard on it. I don't like driving past 4k thoug. I'm pretty much top the floor when I get to the main road by my house shifting at 4k. I love the torque. Lol. But then I'm closing to the gate at base and going slow from there. I do take the car to the grocery store and what not.. but do I rarely go over 50 over a few mile span.. onless going on a weekend trip. So far no problems.


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## grs1961 (Oct 23, 2012)

An important point in relation to the DPF regeneration:

It's not _speed_ that matters, it's how much heat the engine is developing.

As Aussie mentioned above, keep the RPM's above 2000 for about 20 minutes and it cleans the DPF. I had the light come on during summer, a pleasant 40C day, and drove it around the block a few times in second, it only took ten minutes that time!!


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## Tomko (Jun 1, 2013)

The cruze diesel is a wonderful car - but so is a volt. 

In your scenario of a two mile commute, a volt is a much better choice.


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## revjpeterson (Oct 2, 2013)

Two notes on what I've seen so far:

1. Yes, an uninterrupted succession of 2 mile driving intervals will not allow a regen to complete, and it will continue attempting whenever the engine reaches operating temperature until it has completed its regen. If the system is working properly, though, it shouldn't put it into limp mode as a result, because it should display the "keep driving" DIC message prior to making that jump, at which time you need to do so or risk limp mode and the need for a manual regen. Now, if you're on a tight schedule and can't afford to take an unanticipated 20 minute drive on zero notice, it might be good to get out on the highway every 500 miles or so, so that it can regen before it has to give you the "keep driving" message. Another idea would be to get an OBD monitor/scanner that can read the soot level PID from the ECU. When it gets past 20 grams take it out for a drive and avoid the urgent regen-now-or-else situation.

2. The North-American CTD does not use the regen light on the instrument panel like the Australian (and I would imagine the European/Asian) CTD does. The light is present, but not functional, and the car uses the DIC message instead. I have wondered, though, if it is possible to make this light functional through ECU tuning. If the light is equipped with a lamp, or if the lamp can be added, it should be possible to tune the ECU to illuminate it under specified conditions, such as when a regen is active or when the soot level surpasses a specified limit. The question is, does anyone have the knowledge or motivation to accomplish this?


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## VtTD (Nov 5, 2013)

thmike said:


> I only have stopping 2200 miles on my td amd I've never seen a keep driving light yet. My drive to work is around 2 miles also. I'm also pretty hard on it. I don't like driving past 4k thoug. I'm pretty much top the floor when I get to the main road by my house shifting at 4k. I love the torque. Lol. But then I'm closing to the gate at base and going slow from there. I do take the car to the grocery store and what not.. but do I rarely go over 50 over a few mile span.. onless going on a weekend trip. So far no problems.


Thanks very much everyone. This post makes me a little more optimistic. Trading the car is not really an option because I am not willing to take whatever hit in value for a car I just purchased, but more because I love the car. Technically that "keep driving" is supposed to work so I will just make sure I get it out on the interstate once a tank or a little more often. I have a feeling it will happen anyways, but who knows. If I end up having trouble, and the Keep Driving message doesn't do what it's supposed to, I'll have to talk with GM I guess. Thanks again!


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## thmike (Sep 1, 2014)

yah no problem. Sorry for all the spelling errors. My phone just doesn't like to correct itself very good and going back is a pain. I figured you would understand what I was saying. The way I look at it if I have any problems with it the dealership well cover it. At least for a couple years anyways. If I have a ton of problems I'll trade it in when it starts costing me money. That way I won't have such a big hit trading in a car that I just bought. I'm really hoping that gm comes out with a updated tune for the 15s and well reflash the 14s. I cant stand the lag when having to cross traffic.


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