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So here's the latest: The EGR cooler came, but they are missing the gasket. Gasket is on backorder, and GM is shutting down parts manufacturing to make ventilators. I knew that would happen when I read that news. I'd think it was nice but honestly they are so far out of excuses, I don't even care if they finally have a good one. I also have to wonder if there are other factories out there that are shuttered in these difficult times that could actually get back up and running to build the ventilators and help people stay employed, rather than shut down manufacture of what is actually an essential product. In my case I can drive the car and live without the part, but what about work trucks? First responder vehicles??? Or just normal people who need their vehicle for transportation to get to the many essential jobs. Not everyone has backup cars like I do. Dealers are going to run out of loaners. I really hope the ventilator manufacturing actually helps someone, but it doesn't change the fact that GM parts supply is an inexcusable horror show.
 

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Picked the car up from the dealer still unfixed since they might shut down and it could be months before the gasket comes in. I drove it home and noticed unusually poor fuel economy, then it went into regen (that part was expected but but the mpg is usually great until it regen actually kicks in). Even after the regen economy seemed off so I took it out on the highway a while ... it struggled to get 50 mpg on a 25-mile stretch where I usually get 60-65mpg. Then for the last 25 or so miles before I got home it improved and seemed more normal. Weird. No CEL at all still. The car was still driving great and getting great fuel economy when I dropped it off, so I don't really understand what transpired. The invoice says they inspected the EGR cooler and found excessive buildup in it as well as the valve. Upsetting to say the least since this is not an abused car, it's on the highway all the time and I shouldn't be having these issues. This could be related to my regen issue but as mentioned before I'm guessing it is a result, like the regens, and not a cause, so once fixed it will clog again. But I probably have months to wait until it's fixed so I guess I'll hold off on theories. I hope the lousy mpg isn't something that is going to continue.
 

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Well it is good to know that a benefit is to be had by cleaning both your egr valve and the egr cooler .... At least you now know....

I plan to.replace my egr valve and clean up the existing one and out it on the shelf ...

Jeff
 

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Discussion Starter #84
Picked the car up from the dealer still unfixed since they might shut down and it could be months before the gasket comes in. I drove it home and noticed unusually poor fuel economy, then it went into regen (that part was expected but but the mpg is usually great until it regen actually kicks in). Even after the regen economy seemed off so I took it out on the highway a while ... it struggled to get 50 mpg on a 25-mile stretch where I usually get 60-65mpg. Then for the last 25 or so miles before I got home it improved and seemed more normal. Weird. No CEL at all still. The car was still driving great and getting great fuel economy when I dropped it off, so I don't really understand what transpired. The invoice says they inspected the EGR cooler and found excessive buildup in it as well as the valve. Upsetting to say the least since this is not an abused car, it's on the highway all the time and I shouldn't be having these issues. This could be related to my regen issue but as mentioned before I'm guessing it is a result, like the regens, and not a cause, so once fixed it will clog again. But I probably have months to wait until it's fixed so I guess I'll hold off on theories. I hope the lousy mpg isn't something that is going to continue.
Actually the partly blocked EGR might have been causing you to have INCREASED MPG, and cleaning it may well be the reason for the drop. The EGR has zero benefit for efficient operation of the engine, absolutely zero benefit, but plenty of problems are created by dumping dirty exhaust back in the intake side.. and clogging up EGRs is not unique to this engine, it is ALL Diesels that have them (and some Gas engines as well, such as my 1996 Saturn which occasionally sticks from soot).
The "fix" many people with the early emissions Cummins trucks employ is to unplug the EGR and live with the MIL, it's not legal to do so, but the engine runs fine, and MPG goes UP. You can't do that in this engine, nor any of the newer cars, as the EPA demanded that there be consequences for any emissions issue, and that is where the countdowns and limp mode comes from, government mandated making your car LESS reliable and more of a hassle... all the more reasons for driving the old cars, which are legal and have NO emissions of any kind. The irony here is they government effort to clean the air may well end up doing just the opposite, as people move to keep older cars on the road longer. Typical government making the problem worse.

BTW way, your MPGs numbers are much higher than mine, and I'm not getting the frequent regens.. that is interesting. Perhaps yours is running lower EGTs and thus not doing a passive regen, that might explain higher MPG and the frequent regens.. I do notice my wife's car runs higher EGTs than mine, and it does fewer regens.. post recall I'm seeing mine now run a higher EGTs and the regen interval has also gone up. What are your typical EGTs?
 

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Actually the partly blocked EGR might have been causing you to have INCREASED MPG, and cleaning it may well be the reason for the drop. The EGR has zero benefit for efficient operation of the engine, absolutely zero benefit, but plenty of problems are created by dumping dirty exhaust back in the intake side.. and clogging up EGRs is not unique to this engine, it is ALL Diesels that have them (and some Gas engines as well, such as my 1996 Saturn which occasionally sticks from soot).
The "fix" many people with the early emissions Cummins trucks employ is to unplug the EGR and live with the MIL, it's not legal to do so, but the engine runs fine, and MPG goes UP. You can't do that in this engine, nor any of the newer cars, as the EPA demanded that there be consequences for any emissions issue, and that is where the countdowns and limp mode comes from, government mandated making your car LESS reliable and more of a hassle... all the more reasons for driving the old cars, which are legal and have NO emissions of any kind. The irony here is they government effort to clean the air may well end up doing just the opposite, as people move to keep older cars on the road longer. Typical government making the problem worse.

BTW way, your MPGs numbers are much higher than mine, and I'm not getting the frequent regens.. that is interesting. Perhaps yours is running lower EGTs and thus not doing a passive regen, that might explain higher MPG and the frequent regens.. I do notice my wife's car runs higher EGTs than mine, and it does fewer regens.. post recall I'm seeing mine now run a higher EGTs and the regen interval has also gone up. What are your typical EGTs?
Wouldn't the effect on mpgs depend on whether the EGR was stuck open or shut? I could see that cleaning the cooler could decrease mpg because I always thought lower intake temperatures = lower mpg. And if was clogged it would just bypass and send hotter gasses into the intake, which as far as I understand, would lead to better mpg. I don't know how much they cleaned, but I assume they would have cleaned out the valve at least. They listed both the cooler and valve to be replaced, whenever the gasket comes. That would certainly be disappointing if the clean EGR valve is what is killing my mpg. I kind of doubt that because I took this car to Cincinnati and back starting when it had 500 miles on it and I got 66.1 mpg for the out and back trip of 1,200 miles. At around 4,000 miles I took it on another trip of 700 miles and got 66 mpg. So I have to think there is more at play here, since basically new out of the box the car was getting mid-60s mpg on the highway. It definitely goes up and down depending on weather, traffic, fuel, and my speed, but today was noticeably off ... I was going 60 mph on a stretch that is part of my commute, so I am very used to what I should see on the economy tab (the one with the graph-like bars). On the way home of that loop, it seemed a little more consistent with normal, on a crappy rainy day. The other thing I've considered is if something was unplugged long enough, maybe it had to relearn. In that case I would expect it to eventually get back to normal and stay that way.
On a side note while I was getting lower mpg I noticed the car kept going into negative boost ... serious negative boost at idle, and slight negative boost on the highway off the throttle. The boost numbers also seemed to go back to normal in the last 20 miles. That could also be EGR related but I definitely don't think it is normal.
My EGTs, on the highway are usually around 600, give or take, for EGT sensor #1. Both sensors downstream read about 50 degrees lower than that. I have wondered if they are on the low side, leaving me without passive regens. I did not notice any particular deviation from normal today, though I wasn't watching super closely.
 

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Actually the partly blocked EGR might have been causing you to have INCREASED MPG, and cleaning it may well be the reason for the drop. The EGR has zero benefit for efficient operation of the engine, absolutely zero benefit, but plenty of problems are created by dumping dirty exhaust back in the intake side.. and clogging up EGRs is not unique to this engine, it is ALL Diesels that have them (and some Gas engines as well, such as my 1996 Saturn which occasionally sticks from soot).
The "fix" many people with the early emissions Cummins trucks employ is to unplug the EGR and live with the MIL, it's not legal to do so, but the engine runs fine, and MPG goes UP. You can't do that in this engine, nor any of the newer cars, as the EPA demanded that there be consequences for any emissions issue, and that is where the countdowns and limp mode comes from, government mandated making your car LESS reliable and more of a hassle... all the more reasons for driving the old cars, which are legal and have NO emissions of any kind. The irony here is they government effort to clean the air may well end up doing just the opposite, as people move to keep older cars on the road longer. Typical government making the problem worse.
An aside on EGRs, I have three other cars with them: my 1987 Mercedes and both my 2005 Jeep Liberty diesel and my dad's 05 Liberty diesel (he does not drive it anymore so I have it in my care now). The Mercedes' EGR wouldn't clog but it would fill the intake manifold with soot, and that could lead to poor running and general poorer engine health ... no computer involvement so if a vacuum line happens to come unplugged, you basically run cleaner. With the Jeeps there was a commonly available tune that kept everything intact but kept the valve closed with the exception of overboost conditions should they arise, and a kit to remove everything and then tune. These have both been eliminated by recent raids on the makers of them. Which I understand to the extent that they are technically illegal, but the cost and energy to take these places down seems over the top for the impact. Case in point on the Jeeps, I will just go so far as to say I have experience with one that has been reversibly de-EGRed and one that hasn't. The EGRless one smoked less, got much better mileage, didn't gunk up every sensor, and resulted in visually less sooty oil. The stock one needed a head rebuild at 94k miles. I have also heard of many people who passed smog tests with the EGR disabled, though I'm guessing the NOx level difference is more significant in real-life driving. I understand the concern with NOx, but for some vehicles that aren't driven in densely populated areas where smog formation becomes a big issue, I tend to think it is better to have lower CO2 emissions and less soot everywhere than it is to sacrifice those things for lower NOx. Not to mention the cost of the lower NOx also means shorter engine life, which means more need to manufacturer new parts, new engines, or even new cars (huge environmental cost). Don't get me wrong, I love how the Cruze doesn't smoke or stink, and the concept of the emissions systems. I would like to keep them intact even if I had a choice. It's just an uphill battle with EGR technology. I almost wish we could eliminate the EGR but keep the DPF/DEF, though my guess would be the DPF would overload like mad and the DEF system would have a lot more NOx to cope with. Everyone complains about the DPF and DEF systems, and I know they have glitches, but to me the technology of that seems much kinder to the engine than an EGR (which leads to DPF problems often anyway).
 

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Discussion Starter #87
Interesting. Negative boost is typical when the car is trying to raise EGTs and start a regen, the Gen 1's do it much more noticeably than the Gen 2s. I'll have to monitor more, but I seem to almost always see EGT 2 higher than EGT 1 on highway, steady state. That would indicate some passive regen taking place in the DPF.. that you normally see EGT2 lower seems to validate the frequent regens. Perhaps you have a bad EGT2 sensor that is not bad enough to throw a code, but is telling the ECU no passive regen, and hence regens like crazy.. maybe swap EGT1 and EGT2 and see what happens (I think they are the same sensor).. Certainly unlikely to hurt anything.

Your spot on about EGR, and that is why there is a push to get lower compression ratio Diesel engines to work an angle to eliminate EGR altogether, as it is a known problem. I don't see any way an open egr would improve MPG, the dirty air is lacking O2, which is the point, as it lowers in cylinder production of NOx, in a Diesel under light load there is excess air, plenty of pressure, and high temperature.. which gets the NOx going, the EGR works by lowering the O2, but the cost is more soot, which fills the DPF.. The cars could run fine without EGR, but the DEF use would go way up and over work the SCR, which is the reasons they still have EGR, but they use less EGR now than they did with the early LNT (non DEF systems) That is why the 2007.5 to 2012 Cummins Dodge trucks had big issues with clogged DPF and wiped out Turbos when an EGR valve would inevitably stick open, the rest was sure to follow in rapid fashion.

The reason for EGR is not to bring up intake temps, though it can assist with that, it is all about reducing O2, and thus NOx. The Turbo does such a great job of bringing up intake temps, that we have the inter-cooler to make the engine more efficient, because intake temps too high lower efficiency of the engine. The larger the change in temperature in a thermal engine, the more potential for higher efficiency.

You are absolutely correct about the unplug, and relearn.. that is absolutely the way it works.. the ECU will be adjusting from the baseline values, to the measured values and that can take some time, and that is likely what you are seeing with the lower (but still better than most) MPG.
 

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Interesting. Negative boost is typical when the car is trying to raise EGTs and start a regen, the Gen 1's do it much more noticeably than the Gen 2s. I'll have to monitor more, but I seem to almost always see EGT 2 higher than EGT 1 on highway, steady state. That would indicate some passive regen taking place in the DPF.. that you normally see EGT2 lower seems to validate the frequent regens. Perhaps you have a bad EGT2 sensor that is not bad enough to throw a code, but is telling the ECU no passive regen, and hence regens like crazy.. maybe swap EGT1 and EGT2 and see what happens (I think they are the same sensor).. Certainly unlikely to hurt anything.

Your spot on about EGR, and that is why there is a push to get lower compression ratio Diesel engines to work an angle to eliminate EGR altogether, as it is a known problem. I don't see any way an open egr would improve MPG, the dirty air is lacking O2, which is the point, as it lowers in cylinder production of NOx, in a Diesel under light load there is excess air, plenty of pressure, and high temperature.. which gets the NOx going, the EGR works by lowering the O2, but the cost is more soot, which fills the DPF.. The cars could run fine without EGR, but the DEF use would go way up and over work the SCR, which is the reasons they still have EGR, but they use less EGR now than they did with the early LNT (non DEF systems) That is why the 2007.5 to 2012 Cummins Dodge trucks had big issues with clogged DPF and wiped out Turbos when an EGR valve would inevitably stick open, the rest was sure to follow in rapid fashion.

The reason for EGR is not to bring up intake temps, though it can assist with that, it is all about reducing O2, and thus NOx. The Turbo does such a great job of bringing up intake temps, that we have the inter-cooler to make the engine more efficient, because intake temps too high lower efficiency of the engine. The larger the change in temperature in a thermal engine, the more potential for higher efficiency.

You are absolutely correct about the unplug, and relearn.. that is absolutely the way it works.. the ECU will be adjusting from the baseline values, to the measured values and that can take some time, and that is likely what you are seeing with the lower (but still better than most) MPG.
I should actually go through and check that the PID are entered correctly for EGT1 and EGT2, since I seem to see the opposite of what you do ... EGT2 is consistently lower than EGT1, I don't think I have ever seen 2 higher. For me EGT1 is the one that gets very high during an active regen, while EGT2 goes up a bit but is not nearly as dramatic. It's possible I entered the names backwards when I put them in my ScanGauge. Though I thought the first sensor would be the one getting hottest during a regen (in the DOC), which would be consistent with my observations. If my PIDs are right, maybe my low EGT2 is contributing to my lack of passive regen. I can't really imagine what would physically cause lower exhaust gasses between two parts of the DOC/DPF. Maybe I misunderstand passive regens, but I thought they didn't require any input from the computer or anything to be initiated ... I thought they just happened naturally when EGTs rise to a normal level on the highway.
I did take the car on a 79-mile out-and-back highway drive yesterday (been a little cooped up here so I needed a drive anyway) and my fuel economy seemed back to normal for this time of year with 60-70 mph driving. Per the MyChevy App it got 62 mpg for the trip and my DIC looked like it normally does ... both of which I take with a grain of salt based on how off my DIC has been sometimes compared to hand calculation for a tank. But I look for the consistency and trends, accurate or not, and that is what I was seeing before. So either it just needed to relearn its values, or it has reclogged whatever it didn't like having unclogged. I want to say it feels a little faster than before I dropped it off, but I'm pretty sure that has to do with me driving the 62 horsepower car and 70 horsepower car in its absence.
A rep from Chevy Customer Service called me today to follow up about the parts, and at this stage didn't know any more than I do. They said they are going to contact the parts division to find out what the situation is. It apparently is still not listed on back order. Hope they aren't going to tell me its NLA. I can't imagine that seeing as they'd end up having to buy back a lot of cars over a gasket and I doubt they'd want that. I will say they have been really diligent about following up on my case this time.
 

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Discussion Starter #89
"I want to say it feels a little faster than before I dropped it off, but I'm pretty sure that has to do with me driving the 62 horsepower car and 70 horsepower car in its absence"
I got a good chuckle on that one, yep I think that would be it. Just for fun I verified 0-60 in my manual the other night.. 9.3 seconds, and that with traction control limiting torque as I'm still running the studded snow tires. While today there are plenty of cars quicker than that, it was once a pretty standard time for what was known as a muscle car. Yet, none of those cars could do that and also average around 50 MPG. Despite many hassles, these things are technological marvels, and yet that complexity is also leading to some of our frustrations.
 

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I got a good chuckle on that one, yep I think that would be it. Just for fun I verified 0-60 in my manual the other night.. 9.3 seconds, and that with traction control limiting torque as I'm still running the studded snow tires. While today there are plenty of cars quicker than that, it was once a pretty standard time for what was known as a muscle car. Yet, none of those cars could do that and also average around 50 MPG. Despite many hassles, these things are technological marvels, and yet that complexity is also leading to some of our frustrations.
I've never actually tried a serious 0-60 run in mine but I'm guessing 9 seconds is about the best I could do ... I think they were rated around 8.6, though I've seen lower estimated and GM never published a time. I figure the human component in the manual, at least for someone like me, is going to slow it down. One thing I've wondered in this car is if there is some sort of torque limiter in first, because I always feel like first gear starts to feel useless once the car is moving, whereas second really kicks out a burst of torque that feels like it builds all the way up to 3k+. Of course as a diesel there isn't much point in really revving it high, but first just feels like first gear has a dropoff that the other gears don't have.
I think people get really out of touch with how the definition of "fast" has changed ... at least in the US. A 60s Ferrari 250 GT was 0-60 in 8 seconds, as were some of the Jaguar E-Types. Of course one expects standards to change, and those cars were also not made for straight-line 0-60 times (which people also don't understand), but still. It kind of frustrates me that people think of the Cruze diesels as "slow" and that limited their appeal ... because I've driven slow cars, and even average cars, that make this seem like peppy. Of course it isn't fast, but it sure isn't slow either. Any way you cut it, when you factor in the fuel economy, it's an amazing combination to me. I've had a lot of "regular" cars as rentals, and they were all sluggish compared to this ... fuel economy-wise the best one I had was a Ford Fusion Hybrid, which I drove to Boston and back and got 44 mpg for the trip ... a year later I took the Cruze TD on the same trip and got 66 mpg. I did have a Renault Megane diesel manual in the UK three years ago that was similar to the Cruze on both measures, and it was one of the reasons I bought the Cruze a few months later.
 

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Another customer service agent called Friday and told me they still don't have any idea what to expect on the part. No ETA, but they don't know if it's on backorder or not. They said they will send me an email once a week to provide updates ... "once a week" isn't super inspiring in terms of reflecting that they expect this to take multiple weeks.
Meanwhile I drove the car 80 miles each day yesterday and today, and my fuel economy is definitely still down. Not awful but a solid 5 mpg lower than what I normally see. Been over 300 miles so I would think the ECM has relearned by now. Starting to wonder if I should really be driving it a lot if things are actually clogged up. Other than the fuel economy I don't really notice anything different. The regen cycles and soot levels look the same as before.

Edit: Meanwhile AC Delco EGR cooler gaskets are listed on RockAuto as in stock. If that's the same part maybe I should ask the dealer if I can just buy it on RockAuto.
 

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How much are the gaskets? A couple bucks? You buy them and hand them to the dealer for installation if you want it done quickly.
About $7. I'm happy to pay that out of pocket if it means not waiting weeks. I'm pretty sure they were not on RockAuto last week, so I might call the dealer first in case it already shipped for them if it just became generally available. Not that it would hurt to have an extra. I do also want to make sure that is the part they're missing; I'm pretty sure that is what they said but it could have been another seal.
 

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When mine was replaced my long-term mileage was garbage for a while. I don't remember if I ever checked short term or instantaneous.

I chalked it up to them having to idle the car to temperature and force a regen at the dealership, which I imagine took quite some time.
 

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When mine was replaced my long-term mileage was garbage for a while. I don't remember if I ever checked short term or instantaneous.

I chalked it up to them having to idle the car to temperature and force a regen at the dealership, which I imagine took quite some time.
Out of curiosity what do you mean by short-term vs long-term mileage? For trends I usually look at the screen that shows sort of graph bars (each one accounts for about 3 miles) ... with the same commute I've gotten used to what bars I can expect for which chunks of highway (OCD, I know). That's what has been down for me lately that concerns me a bit ... granted, my repair did not get completed, so I probably should wait to see. I'm guessing you're right and the idling and forced regen (plus just general moving the car around from lot to shop while it's there) really knocks out your tank mpg. I would expect the "last 25" and "last 50" numbers to be awful for a while too. I think it also has to relearn the EGR positions and probably some other information, which will throw off economy. Between those I'm trying to prepare myself not to have a heart attack in the first few miles when I get it back!
 

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I pretty much always leave the last 450 mile average up. Mine normally hovers around 54 but after the recall was around 49 until I had gone almost all of those 450 miles again.

That tells me there was probably a huge and terrible outlier data point from the service.
 

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I have reused a variety of caskets over the years with no issues. They could also a bit of gasket sealer. I know they are trying to follow the GM book but if its really causing you issues, this would be what I would suggest they do.

Since this engine is used in Europe, you could also expand your search to international parts sources.
 

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It depends on the gasket - but GM is a large fan of MLS gaskets, which generally are very reusable.
 

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I tried to order the EGR cooler gasket from Rock Auto today and it let me put one in the cart, but when I tried to proceed to checkout, it removes the item and says "not available". So my guess would be third-party parts stores are in the same non-descript limbo that GM leaves everyone else in. I shouldn't be surprised, but sometimes I just step back and honestly cannot believe GM gets away with being this horrendous on parts supply. With zero accountability. There are NLA parts on a two-year-old car under warranty, and all they have to say about it is a scripted "we're sorry for the inconvenience" for the 40th time.
 

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I tried to order the EGR cooler gasket from Rock Auto today and it let me put one in the cart, but when I tried to proceed to checkout, it removes the item and says "not available".
Sounds like Rock Auto does a lot of drop shipping. Their inventory says they have a part and when you order they just tell some other place to ship it directly to you. Rock Auto inventory is wrong because they didn't know GM doesn't have it until you tried to place the order.

I had the same problem years ago when trying to order a new ignition switch for a 1985 BMW motorcycle. I waited three weeks for the order to ship and finally called them only to find they looked through their computer system and turns out they didn't have the switch and couldn't ship it. It then cost 3x as much to get it from BMW, shipped from somewhere in Europe.
 
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