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SEGR/Turbo/GDE Related Question
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Author:  ChesterCRD [ Thu Jul 02, 2009 12:49 pm ]
Post subject:  SEGR/Turbo/GDE Related Question
GDE noted in a post:

GreenDieselEngineering wrote:
Will it work with SEGR? Yes, however if the EGR is completely blocked you will not have proper control of the turbo to prevent surging. Surging causes low cycle fatigue failures of the compressor wheel, not a good thing. We understand the concept of SEGR and its benefits, but hardware changes can have detrimental affects to other systems on the engine.


This gets me wondering about the safety of the SEGR. I know a lot of discussion and thought went into it and I'm pretty sure I even saw this discussed at some point, but I can't locate it. Does the SEGR allow the control of the turbo that GDE mentioned, or is it nearly functionally equivalent to blocking off the EGR?
Author:  GreenDieselEngineering [ Thu Jul 02, 2009 1:05 pm ]
Post subject: 
The SEGR concept is functionally equivalent to blocking off the EGR circuit. When the SEGR is "active" (same as unplugging the MAF connector), a pending code for the MAF will be active that shuts the EGR valve. When this fault is active, the EGR will not respond to any other inputs and remains at this level, thus disabling the turbo surge protection functionality.

I hope this can help to answer your question, don't hesitate to reply in case of any more questions.
Author:  UFO [ Thu Jul 02, 2009 1:48 pm ]
Post subject: 
The SEGR simulates EGR, so although EGR is eliminated, the ECM does not know it. Personally I don't want exhaust gas and soot clogging my intake. Turbo surging is not a problem on a throttleless engine, as you can never cut off the air flow fast enough to create the conditions that generate a surge, especially with the SEGR disabling the flow control valve as well.
Author:  geordi [ Thu Jul 02, 2009 3:05 pm ]
Post subject: 
UFO, thank you for finally clarifying this. For me at least, I know that I don't want the EGR to ever open, but wasn't certain what they were talking about with turbo "surging" or even the continual use of the term "throttle tip-in and tip-out" like everyone knows what that means. Maybe I'm just not as smart as the rest, but the throttle doesn't "tip" anything on my CRD. Its either being applied by my foot, or it isn't.

I am still considering either the GDE or the InMotion tunes, and I do ask a lot from my vehicles. So I would be leaving the SEGR in place because I *know* that it disables the EGR completely - that wire in the center is unhooked and I have over 30k miles without an EGR code. The MAP was all oily and yucky the last time I checked it, and that will be rectified when I finally am able to install a ProVent. But IF I get the GDE, the SEGR will remain installed. I understand that as a company, they have to dance a LOT to avoid the lawyers of the EPA finding them and killing them... But at the same time, I am a bit hesitant about some of the answers and descriptions offered about the tune.
Author:  Joe Romas [ Thu Jul 02, 2009 3:06 pm ]
Post subject: 
geordi wrote:
UFO, thank you for finally clarifying this. For me at least, I know that I don't want the EGR to ever open, but wasn't certain what they were talking about with turbo "surging" or even the continual use of the term "throttle tip-in and tip-out" like everyone knows what that means. Maybe I'm just not as smart as the rest, but the throttle doesn't "tip" anything on my CRD. Its either being applied by my foot, or it isn't.

I am still considering either the GDE or the InMotion tunes, and I do ask a lot from my vehicles. So I would be leaving the SEGR in place because I *know* that it disables the EGR completely - that wire in the center is unhooked and I have over 30k miles without an EGR code. The MAP was all oily and yucky the last time I checked it, and that will be rectified when I finally am able to install a ProVent. But IF I get the GDE, the SEGR will remain installed. I understand that as a company, they have to dance a LOT to avoid the lawyers of the EPA finding them and killing them... But at the same time, I am a bit hesitant about some of the answers and descriptions offered about the tune.


But you've had turbo problems :wink:
Author:  geordi [ Thu Jul 02, 2009 4:05 pm ]
Post subject: 
Absolutely correct Joe. Can you tell me that the turbo was surging and not that it ate its bearings from lack of lubrication b/c I had cold oil? That is the real question. My engine was stock, the ONLY mods at that time was the SEGR and an Edge Trailjammer in position 2 (not the hyper-power mode). I have said from the beginning, I believe that I could have prevented the turbo failure by waiting for the engine to properly warm up or having it plugged in overnight. The subsequent engine damage happened while I was coasting and not knowing that the oil was being pumped into the exhaust b/c I didn't have any sort of a boost gauge or EGT to tell me the turbo was dead. Expensive lesson. Will this ever happen to me again? No, b/c I will now have gauges, and I plan to get one of those automated kick-out plugs that ambulances and fire trucks have to keep the oil warm in the winter.

Hindsight. I didn't let it warm up, and it hadn't been plugged in that night. It had been below 20 degrees that night, and it was only 32 at 1pm when I left. Yea, I should have plugged it in. But was this something that the EGR had anything to do with? Doubtful. UFO opened my eyes with his post. I hadn't made the connection that he did. If you have a GAS engine turbocharged, if you suddenly release the throttle at high boost, the throttle throat snaps shut. All the boost has nowhere to go except back into the compressor wheel, which is why a release point is needed. I've never had a turbocharged gas vehicle, so if this is what a blow-off valve is, I don't know.

On a diesel however, the airflow is almost constant. It is either atmospheric or boosted, there isn't a throttle plate to ever close. (FCV notwithstanding) If you suddenly drop the throttle at full boost... All that air STILL enters the combustion chamber on the next cycle, it just doesn't get anywhere near the fuel to continue the WOT run. So the engine just jumps to super-lean operation. Not a problem for a diesel, thats where they idle.

So why would they say that the EGR is used as a pressure release point? to cover their own arses. Totally understandable.
Author:  Joe Romas [ Thu Jul 02, 2009 5:59 pm ]
Post subject: 
I hear and understand what your saying but I've driven over 200k miles on two different tdi's with Garrett vnt turbos and never plugged eather one in. In fact only the 96 Passatt had a block heater.

Now I've seen some pretty thick diesel motor oil past due for a change. Could that have contributed to what happened?

But for my turbo if there's any chanch of what they are saying I'm happy :lol:
Author:  geordi [ Thu Jul 02, 2009 7:52 pm ]
Post subject: 
It was about due for an oil change at that time, and I have also driven VW TDIs that were never plugged in. Did I have 0w-40 in it? No. It had delvac synth in it, but after so many months, I can't recall exactly what grade it was. I have since been informed by a friend that works at a mopar dealer that 0w-40 is the spec oil, that is news to me. I thought it was 15w40. Either way, I will be checking this for certain against the engine's stickers directly, and using the rated stuff.

If keeping the thing plugged in keeps it safe, then that is what I will do. We should remember, this isn't an over-engineered German VW. It is an Italian engine design, muddled up by lawyers in Detroit. Who knows if their suggested oil really is safe either. I will be asking VM directly when I contact them to buy the parts to rebuild the old engine.
Author:  Joe Romas [ Thu Jul 02, 2009 10:00 pm ]
Post subject: 
geordi wrote:
I have since been informed by a friend that works at a mopar dealer that 0w-40 is the spec oil, that is news to me. I thought it was 15w40. Either way, I will be checking this for certain against the engine's stickers directly, and using the rated stuff.


The owners manual calls for Mobil1 0-40 like he says. But it goes on to say if it's not available then 5-40 synthetic is ok :lol: That's what Shell Rotella in the blue bottle is and I think most here use it :wink:

But if you look in the FSM for the "export" spec you'll see something thicker called for :roll: If you were running 15/40 it was most likely not a synthetic and it could have been what took out your turbo :cry:
Author:  geordi [ Fri Jul 03, 2009 1:26 am ]
Post subject: 
As I said, I'm not certain of the winter weight, but the oil that I have always used is Mobil 1 Delvac fully synthetic. There are some synth 15w-40 oils, it just depends on if they are API rated for diesels. Rather than trust a brand name or specific package, I look for that API rating of CJ-4. Only diesel oils are rated C-anything b/c we are "C"ompression engines. :D The S-ratings on all oils are for sparky engines b/c they are smart guys who rate this stuff. :p

The Mobil 1 Delvac is in silver jugs and sold by the gallon at truck stops. It is almost impossible to find at the auto parts store in that format, or in quarts... BUT, the Mobil 1 Turbo Diesel Truck (or Truck and SUV sometimes) in quarts at the parts store IS the same product. I just looked, and according to Mobil's website, the Delvac 1 (synth product) and the Turbo Diesel Truck are both 5w-40. So I am remembering wrong.

Don't forget, I haven't put ANY oil into the engine in close to a year now. I run 5k mile changes, and like I said... It was about due when everything went bang tinkle tinkle tinkle. That was in early February.
Author:  nursecosmo [ Fri Jul 03, 2009 3:35 am ]
Post subject: 
UFO wrote:
The SEGR simulates EGR, so although EGR is eliminated, the ECM does not know it. Personally I don't want exhaust gas and soot clogging my intake. Turbo surging is not a problem on a throttleless engine, as you can never cut off the air flow fast enough to create the conditions that generate a surge, especially with the SEGR disabling the flow control valve as well.


Indeed one can overpressure a turbo diesel engine. It usually happens during gear changes, when the boost is high but the engine RPM suddenly changes. Over pressure is not very common however with VGT systems but it can happen. The more common problem with a VGT system is turbo surging, which is a different phenomenon. Here is a link to some nice flow maps of turbo surging in an engine with the same Garret VNT 15 which we have in the CRD. http://forums.tdiclub.com/showthread.php?p=417918
Remember that anytime air flow goes to the left of a flow map, surging probably will occur.
Whether or not our CRDs do indeed have blowoff logic built into the EGR circuit from the factory, I don't know, but it would certainly be nice if they did.
Author:  UFO [ Fri Jul 03, 2009 10:42 am ]
Post subject: 
For a throttled engine, the "blow off" to relieve a surge is a release of boost either into the atmosphere or back into the pre-turbo intake. It's something else to open the EGR and get a reverse flow into the already pressurized exhaust. The EGR exhaust-side is pre-turbine and generally higher pressure than the manifold; to push flow backwards is not likely to slow the turbo....

Sorry, I like Geordi's explanation of why GDE justifies the existance of a functional EGR. I'm also likely to get a GDE tune as well, I am just going to retain the SEGR.
Author:  linewarbr [ Fri Jul 03, 2009 11:18 am ]
Post subject: 
I wonder if maybe GDE meant that they keep the EGR enabled so that in a turbo surge stuation, the FCV can be opened to allow escape. The SEGR eliminates FCV control except at shutdown, correct? If they are talking about opening the EGR to bleed off boost, then the FCV has to open since there is no direct link between the EGR valve and the intake except through the FCV.

In a few weeks I will pull my MAP sensor to see what kind of buildup is on it. If there is a bunch of soot, we may have an answer.
Author:  Ranger1 [ Fri Jul 03, 2009 12:22 pm ]
Post subject:  Turbo surge
Some of us had surge issues, sometimes called turbo bark, from day one on our early model 2005 CRD's. We also had that put you back in your seat rush of acceleration that disappeared with the series of flashes Chrysler pushed out the door after the CRD shipped. The symptoms I experienced were a loud, barking, raspy noise that would sometimes occur immediately after accelerating, then letting off of the accelerator. It was noisy and annoying. A little investigation (back then before this site and a knowledge base on CRD's existed) with some Ford and GM diesel pickup owners helped reveal the same issue on a few but not the majority of diesel pickups. The sudden deceleration of the engine while the boost pressure was still building caused a backflow into the compressor that makes for an unpleasant noise and added stress on the compressor wheel and shaft. I had to learn to drive around it. I knew of 2 others with the same noise/issue on their CRD's, but no more than that. It seems to me that if you have this issue you know it, either from the noise or your boost gauge readings.

F37 eliminated that problem, as well as acceleration, power and fuel economy for me. It was overkill to that issue and the shift points were changed to avoid overstressing the inadequate tc's being shipped by Chrysler. As proven by InMotion, RocketChip and now GDE, a better tune can eliminate that issue even while increasing power. It just took effort and a decision to do it right, a process that was not part of Chrysler Corporate management.

I will also add that even since upgrading the TC/tranny pump as well as 2 different tunes, I do not have turbo surge as evidenced by my boost gauge. There is nothing but smooth, rapid build of boost, even to the 22 - 25 psi range and smooth quick dropoff when the auto tranny shifts or releasing the accelerator pedal while under full load. When the CRD was first introduced, then VP of Jeep Jeff Bell wrote in an interview that the CRD turbo system was a 26.5 psi design. If that's true, we have a bit of headroom over most tunes running at 22 psi. I've seen surge on a TDI boost gauge and it's not a pretty sight. I've run the InMotion stage II tune for over a year and now Jeff Robertson's RC tune for the CRD (supplied by his European partner) for 6 months, which has even more low end torque than the InMotion stage II, and it hasn't surged a single time with either tune. This lack of surge is while providing smoother, faster boost build and quieter engine performance. It just runs smoother, without turbo surging as shown by a boost gauge. The boost gauge is electric, with it's own map sensor connected at the manifold on the engine itself, directly into the chamber/plenums feeding the intake valves. If it was present, it would show up at some point on the gauge.

I agree with UFO that the pre-turbo exhaust pressure is higher under acceleration, but when the tranny shifts or fueling drops, it drops quickly and rapidly. It's not a static environment. If the GDE tune is optimized to only briefly open the egr valve during those periods of shifting or sudden fueling drop, it will likely blow boost out through the exhaust for a brief moment of time, enough to prevent a surge. It seems to be a good safe approach for a failsafe design, all things being equal. Unfortunately, the egr valve design has not proven to be all things equal. rather failure prone in my case and I'm slightly concerned that even using it for this feature may end up with it failing open once again. I'm concerned about that because it's happend to me twice in the first 18 months of CRD ownership. Even then, it's still less expensive to change it out than a turbo, but only if you actually have turbo surge. The GDE tune appears to offer it as a safety feature.

IMO, their tune is great for the majority of stock CRD's out there running stock or F37 Chrysler quality torque converters. I love the approach they took, with full instrumentation during development. It's a great solution for any CRD with a stock torque converter.

For the few who have a TC more than capable of handling high torque, with tens of thousands of vibration free shifting and trouble free miles using tuned PCM's, it offers a solution to a problem that no longer exists on their CRD's.

For those who don't have the upgrades, it should be a very good offering. If you want to run it with all of the features and have a segr installed, just put your loopback plug in and you're good to go. The segr will not set any codes, pending or otherwise if it's properly built and installed. I've monitored for codes on a CRD equipped with a segr for almost 2 years and it never has set any codes, pending, or stored freeze frame data, using 3 different scan tools, including a DRB dealer scan tool. I've deliberately pulled maf sensors, and set other codes on a CRD with a segr, then cleared them and they never came back.

It's nice to have choices. There is now a tune available for everyone, whether your CRD is stock or modified.
Author:  Joe Romas [ Fri Jul 03, 2009 12:27 pm ]
Post subject: 
Ranger1

Very well stated :D

Joe
Author:  nursecosmo [ Fri Jul 03, 2009 1:52 pm ]
Post subject: 
UFO wrote:
For a throttled engine, the "blow off" to relieve a surge is a release of boost either into the atmosphere or back into the pre-turbo intake. It's something else to open the EGR and get a reverse flow into the already pressurized exhaust. The EGR exhaust-side is pre-turbine and generally higher pressure than the manifold; to push flow backwards is not likely to slow the turbo....

Sorry, I like Geordi's explanation of why GDE justifies the existance of a functional EGR. I'm also likely to get a GDE tune as well, I am just going to retain the SEGR.


Exauast pressure can never be higher than boost pressure during acceleration (generally a ratio of 2:1). If you had 22#s of back pressure, the engine wouldn't run very well.
Author:  linewarbr [ Fri Jul 03, 2009 2:03 pm ]
Post subject: 
Joe Romas wrote:
Ranger1

Very well stated :D

Joe


x2. It's not about whether the GDE tune is better, it is about whether it is better for you.
Author:  UFO [ Fri Jul 03, 2009 9:27 pm ]
Post subject: 
nursecosmo wrote:
UFO wrote:
For a throttled engine, the "blow off" to relieve a surge is a release of boost either into the atmosphere or back into the pre-turbo intake. It's something else to open the EGR and get a reverse flow into the already pressurized exhaust. The EGR exhaust-side is pre-turbine and generally higher pressure than the manifold; to push flow backwards is not likely to slow the turbo....

Sorry, I like Geordi's explanation of why GDE justifies the existance of a functional EGR. I'm also likely to get a GDE tune as well, I am just going to retain the SEGR.


Exauast pressure can never be higher than boost pressure during acceleration (generally a ratio of 2:1). If you had 22#s of back pressure, the engine wouldn't run very well.
You probably meant 1:2. Maybe there can be some mitigation of surge with EGR, and it sounds like some people have experienced it. My CRD does not do that, so there it is.
Author:  ChesterCRD [ Fri Jul 03, 2009 9:41 pm ]
Post subject: 
Thanks for the feedback everyone. I too am considering the GDE tune. $550 is lot of my toy budget in the current climate so I have to decide when the time is right.

I need to do some more reading because some of what's been said is over my head concerning whether high turbo pressures can happen during sudden engine speed changes and how these come to pass. I really like the idea of totally disabling the EGR since the implementation is so flawed.

Anyway, I'm glad to have all the feedback and will doing some research before making my decision. Thanks again.
Author:  geordi [ Fri Jul 03, 2009 9:43 pm ]
Post subject: 
I'm with UFO again. What you have described, and what others have described in that OOOOOLLLLLDDDDD thread on Fred's TDIclub... My CRD and my VW have never done that. What that sounds like (to me anyway) is a turbo with slow actuation of the vanes for reasons unknown. I drive my cars like I stole them, so the turbo is ALWAYS working in and out. My Jetta measured out at the BRAND NEW spec at 150k miles with a compression test, and the guy that bought it wanted to know what was wrong with his OTHER Jetta, an exact duplicate of mine... Except mine was LOTS faster AND had better economy... With higher mileage that his.

Flog the little mule once in a while, and blow the crap out the tail. Its fun and healthy for the engine! :D
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