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Discussion Starter · #1 · (Edited)
Hello Everyone. I have been a following member for quite a while and have found the information in this forum very helpful. I have a 2014 CTD that i purchased in September 2013. I drive mixed 80/20 highway/city. I maintain the car well and its been very reliable for me, but I have experienced a few issues that i have been able to relate to on this site. Bucking (mild and severe) after coasting or light throttle, and a huge lag (almost a stumble) when hot in start/stop situations. I've also experienced several random hard downshifts. These problems first occurred when the car was about 1 year old (not that bad or often) and they seemed to improve after the first emissions recall. Shortly after the latest recall, the symptoms reappeared and gradually became worse.

Background/history:
107,000km
O2 Sensor replaced for P026C code - Mid 2015
DEF Tank Heater - Aug 2016
Emission Recall 15594 - Ran great after recall, but still got occasional P026C code
Emission Recall 17089 - Above mentioned symptoms re-appeared and gradually got worse

Two posts caught my attention: 15 cruze won't start or run, and Help diagnose bucking during regens. Since reading these posts, i have cleaned my EGR valve and the intake valve (throttle plate). Thank-you IndyDiesel for the write-up on cleaning your EGR valve - it went well, just as you described it. I did not replace the gasket plate but probably will if I service the EGR valve again. There is coolant behind the gasket plate and if you have any pressure in the cooling system, it will drip while the EGR valve is out (i had a small panic when i saw this). I have attached four pictures below. 1.) Location of EGR and gasket plate 2.) Intake pipe removed looking into throttle body 3.) close-up of the very gummed up throttle valve 4.) valve body after cleaning

I did the EGR first, about 5 days before i cleaned the throttle body. I noticed a significant improvement in fuel economy and acceleration. The valve was not stuck open, but it was not moving very free and it would sometimes bind up. I used brake clean and worked the valve back and forth with an attached vise-grip. I was pleased with the improvement in performance, but the car was still bucking, mostly first thing in the morning.

When I removed the intake pipe at the throttle body i pushed the plate closed with my finger and it did not release on its own spring tension, but would pop free after a second or so. I figured this could be the cause of the bucking. Cleaning this was much more challenging. I used throttle body cleaner sprayed on rags and a small plastic scrapper to do most of the cleaning. Since so much crap was falling down onto the bottom of the intake (just on the bottom where i could still see it) , i rigged up a small plastic hose (about 3/8 inch) connected to my shop vac to suck out all the carbon debris. What a mess in there - really disappointed to see. I think i could have removed the whole throttle body assembly as well which would make this much easier and allow access to clean further into the intake. Care should be taken to not spray any cleaners directly into the intake since any residual solvents would ignite and combust very different than diesel fuel, potentially causing significant engine damage.

So not sure why my intake got so gummed up. Are there any other reports on this? I've always used the proper engine oil and my UOAs have looked very good. I drive a lot of highway miles, but i could be a bit light on the throttle. All that stuff had to come through the PCV, so I may have to look at that further (catch can....ect.). I also find it interesting these symptoms came back after the latest emissions recall. I will be keeping an eye on the intake valve for sure. The car is running great again with fuel economy back up to near the best i've ever seen, and the bucking is gone, even during the regen it did today. I sure love this little car and hope this helps anyone having similar issues.

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2014 LT program car, Pull Me Over Red, 1.4T Auto
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Hello Everyone. I have been a following member for quite a while and have found the information in this forum very helpful. I have a 2014 CTD that i purchased in September 2013. I drive mixed 80/20 highway/city. I maintain the car well and its been very reliable for me, but I have experienced a few issues that i have been able to relate to on this site. Bucking (mild and severe) after coasting or light throttle, and a huge lag (almost a stumble) when hot in start/stop situations. I've also experienced several random hard downshifts. These problems first occurred when the car was about 1 year old (not that bad or often) and they seemed to improve after the first emissions recall. Shortly after the latest recall, the symptoms reappeared and gradually became worse.

Background/history:
107,000km
O2 Sensor replaced for P026C code - Mid 2015
DEF Tank Heater - Aug 2016
Emission Recall 15594 - Ran great after recall, but still got occasional P026C code
Emission Recall 17089 - Above mentioned symptoms re-appeared and gradually got worse

Two posts caught my attention: 15 cruze won't start or run, and Help diagnose bucking during regens. Since reading these posts, i have cleaned my EGR valve and the intake valve (throttle plate). Thank-you IndyDiesel for the write-up on cleaning your EGR valve - it went well, just as you described it. I did not replace the gasket plate but probably will if I service the EGR valve again. There is coolant behind the gasket plate and if you have any pressure in the cooling system, it will drip while the EGR valve is out (i had a small panic when i saw this). I have attached four pictures below. 1.) Location of EGR and gasket plate 2.) Intake pipe removed looking into throttle body 3.) close-up of the very gummed up throttle valve 4.) valve body after cleaning

View attachment 241546 View attachment 241554 View attachment 241562 View attachment 241570

I did the EGR first, about 5 days before i cleaned the throttle body. I noticed a significant improvement in fuel economy and acceleration. The valve was not stuck open, but it was not moving very free and it would sometimes bind up. I used brake clean and worked the valve back and forth with an attached vise-grip. I was pleased with the improvement in performance, but the car was still bucking, mostly first thing in the morning.

When I removed the intake pipe at the throttle body i pushed the plate closed with my finger and it did not release on its own spring tension, but would pop free after a second or so. I figured this could be the cause of the bucking. Cleaning this was much more challenging. I used throttle body cleaner sprayed on rags and a small plastic scrapper to do most of the cleaning. Since so much crap was falling down onto the bottom of the intake (just on the bottom where i could still see it) , i rigged up a small plastic hose (about 3/8 inch) connected to my shop vac to suck out all the carbon debris. What a mess in there - really disappointed to see. I think i could have removed the whole throttle body assembly as well which would make this much easier and allow access to clean further into the intake. Care should be taken to not spray any cleaners directly into the intake since any residual solvents would ignite and combust very different than diesel fuel, potentially causing significant engine damage.

So not sure why my intake got so gummed up. Are there any other reports on this? I've always used the proper engine oil and my UOAs have looked very good. I drive a lot of highway miles, but i could be a bit light on the throttle. All that stuff had to come through the PCV, so I may have to look at that further (catch can....ect.). I also find it interesting these symptoms came back after the latest emissions recall. I will be keeping an eye on the intake valve for sure. The car is running great again with fuel economy back up to near the best i've ever seen, and the bucking is gone, even during the regen it did today. I sure love this little car and hope this helps anyone having similar issues.
Welcome Aboard!:welcome:

With your first write-up done as well as that, I look forward to some How-To's and other exposes' as well from you!

Don't forget to introduce yourself and your Cruze here.

EDIT: Fix your pic's!
 

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Wow, had no idea the INTAKE side would be subject to so much fouling. Would expect the exhaust side to look like that but not the Throttle Body.

Excellent write up and thanks for including the pictures!
 
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EGR has been doing that to Mercedes diesel intakes for the past 30 years. My 1979 was the last year for a turbo without EGR, my newer cars have had their EGRs disabled.

I hoped the latest common rail systems wouldn't be as sooty, but apparently that was wishful thinking.
If I had a CTD, I'd clean the intake and put a tune in it that doesn't open the EGR valve.
 

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2014 Cruze Diesel, 2007 Cobalt, 1981 Camaro Z28, 2017 Volt
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Thinking I may try tackling this today (if its not raining), prior to our trip up north tomorrow. I'll probably just remove the throttle valve, though. That way I don't have to worry about what I use, and all the crap I cleaned out.
 
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Discussion Starter · #8 ·
Thinking I may try tackling this today (if its not raining), prior to our trip up north tomorrow. I'll probably just remove the throttle valve, though. That way I don't have to worry about what I use, and all the crap I cleaned out.
Good call. Curious how your intake looks. Great time to do this before a long trip!
 

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2014 Cruze Diesel, 2007 Cobalt, 1981 Camaro Z28, 2017 Volt
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Good call. Curious how your intake looks. Great time to do this before a long trip!
For sure - especially with so much freeway. I've noticed that it really hasn't been as great on the freeway as it used to be. I'm hoping this is all related.
 

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With my car being for last 25k miles being almost all highway miles, I am coming to the conclusion that driving our diesels hard on a regular basis might help. So the old saying drive it like you stole it might help more than I thought. The easiest way to do it is to run for a mile or two at 4000 rpm with the transmission in manual mode, maybe once a week. I think it could help, when dealer does a manual regen it is at 3000 rpm for an extended period of time, so I can't imagine 4000 rpm for a couple min would harm anything.
 

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2014 Cruze Diesel, 2007 Cobalt, 1981 Camaro Z28, 2017 Volt
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For the last few years, the majority of tanks are 80-100% city, for what it's worth.
 

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Discussion Starter · #12 ·
With my car being for last 25k miles being almost all highway miles, I am coming to the conclusion that driving our diesels hard on a regular basis might help. So the old saying drive it like you stole it might help more than I thought. The easiest way to do it is to run for a mile or two at 4000 rpm with the transmission in manual mode, maybe once a week. I think it could help, when dealer does a manual regen it is at 3000 rpm for an extended period of time, so I can't imagine 4000 rpm for a couple min would harm anything.
Agree - About a week before I cleaned my EGR valve, I tried running the car harder than normal. I was keeping the trans in manual gear 6 and letting the engine run full load up some moderate hills, letting off once I was too far over the speed limit. After a week of this I was seeing higher peak boost values. I think at full throttle full load, the EGR should be closed? So repeating this may have started to free up the valve. I took the EGR valve off as the performance was still inconsistent.
High RPM may be effective too, but it's hard to keep the engine at a full load at 3500rpm. The 2.0 CTD does not seem to be lugging in 6th gear at full throttle. I will make a habit of this on my drive home when possible.
 

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With my car being for last 25k miles being almost all highway miles, I am coming to the conclusion that driving our diesels hard on a regular basis might help. So the old saying drive it like you stole it might help more than I thought. The easiest way to do it is to run for a mile or two at 4000 rpm with the transmission in manual mode, maybe once a week. I think it could help, when dealer does a manual regen it is at 3000 rpm for an extended period of time, so I can't imagine 4000 rpm for a couple min would harm anything.
theres a 8 mile 10% hill on my way to work, 4000+ engine braking down the hill, 4000+ lower gear up the hill, every time
 

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2014 Cruze Diesel, 2007 Cobalt, 1981 Camaro Z28, 2017 Volt
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theres a 8 mile 10% hill on my way to work, 4000+ engine braking down the hill, 4000+ lower gear up the hill, every time
That's what I miss about not driving to North Carolina anymore (in-laws moved to Atlanta) is driving on I-77/I-64 through the Appalachians.

Full decel-fuel-cut, engine braking down that grade while going 70 was a blast!
 

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I do a lot of easy 60 mph highway, wondering now if at 70K miles my intake may be gumming up too.

Are you all saying the 4000 rpm "drive it like u stole it" every once in awhile wil clean a dirty throttle body or just help keep it from gunking up AFTER it's been physically cleaned?
 

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Just the nature of the beast, EGR that is.
I'm not surprised and pretty much expected to see this. Just like the old MB diesels the light duty 6.2 and 6.5L V8 engines that have egr gum up the intakes. What's new is the throttle valves, coolers and sensors.

To the OP, nice post and my t/v, egr is on the list for sure.
 
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I do a lot of easy 60 mph highway, wondering now if at 70K miles my intake may be gumming up too.

Are you all saying the 4000 rpm "drive it like u stole it" every once in awhile wil clean a dirty throttle body or just help keep it from gunking up AFTER it's been physically cleaned?
i cant see how it would clean a dirty one.

when wife brings car back after the weekend im gonna have a look at my egr and throttle plate
 
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