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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N57 / M57 Turbo Diesel Discussions - 335d > Carbon build up! Here is how to stop it!



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      06-14-2014, 03:45 PM   #111
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It always comes down to Government regulations, the design of the engine is spot on, the gas we use sucks, hence BIG OIL COMAPINES, AND THE GOVERNMENT IN THERE BACK POCKETS, they kinda work hand in hand for their gain and our loss...
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      06-14-2014, 05:13 PM   #112
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Quote:
Originally Posted by Jffeijao View Post
On diesel engines the improvement is smaller then on gas, but also occurs.
On a 335d, deleting the EGR leads to better warm operating mileage. Quite simply, our EGR does not increase operating efficiency and the only efficiency related benefit it provides is quicker warm up. Other than that, every moment is dedicated to lessening efficiency and ultimately leads to significantly reduced efficiency (bad mileage due to CBU).

Some good theories on potential EGR benefits, but until they actually materialize on a car and prove themselves beneficial they are just theories. None of which are going to come to exist on the engine we are discussing since its already produced and in use, so it really doesn't matter. I am not advocating the permanent deletion of all egrs cuurent, past, and future, though I would be extremely disappointed to see then come back as even in gas cars they leave crud in the intake.
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      06-14-2014, 07:49 PM   #113
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Quote:
Originally Posted by Hoooper View Post
On a 335d, deleting the EGR leads to better warm operating mileage. Quite simply, our EGR does not increase operating efficiency and the only efficiency related benefit it provides is quicker warm up. Other than that, every moment is dedicated to lessening efficiency and ultimately leads to significantly reduced efficiency (bad mileage due to CBU).

Some good theories on potential EGR benefits, but until they actually materialize on a car and prove themselves beneficial they are just theories. None of which are going to come to exist on the engine we are discussing since its already produced and in use, so it really doesn't matter. I am not advocating the permanent deletion of all egrs cuurent, past, and future, though I would be extremely disappointed to see then come back as even in gas cars they leave crud in the intake.
Ill advocate the permanent deletion of all egr's, lol
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      06-14-2014, 08:45 PM   #114
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Quote:
Originally Posted by Hoooper View Post
On a 335d, deleting the EGR leads to better warm operating mileage. Quite simply, our EGR does not increase operating efficiency and the only efficiency related benefit it provides is quicker warm up. Other than that, every moment is dedicated to lessening efficiency and ultimately leads to significantly reduced efficiency (bad mileage due to CBU).

Some good theories on potential EGR benefits, but until they actually materialize on a car and prove themselves beneficial they are just theories. None of which are going to come to exist on the engine we are discussing since its already produced and in use, so it really doesn't matter. I am not advocating the permanent deletion of all egrs cuurent, past, and future, though I would be extremely disappointed to see then come back as even in gas cars they leave crud in the intake.
Hopefully once SCR efficiency increases EGR will no longer be needed. It's already being done with heavy duty diesel engines (agricultural)*

* NOX targets are less strict when compared to cars/trucks.
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      06-15-2014, 08:32 AM   #115
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Originally Posted by Jffeijao View Post
You are correct when you consider old technology EGR.
However with all actuators in the engine being controlled by software, EGR can improve the efficiency of combustion engines. Below is how:

1- Reduced throttling losses. The addition of inert exhaust gas into the intake system means that for a given power output, the throttle plate must be opened further, resulting in increased inlet manifold pressure and reduced throttling losses. (Gasoline engines only as diesels are not throttled)

2- Reduced heat rejection. Lowered peak combustion temperatures not only reduces NOx formation, it also reduces the loss of thermal energy to combustion chamber surfaces;

3- Reduced chemical dissociation. The lower peak temperatures result in more of the released energy remaining as sensible energy near TDC (Top Dead-Center), rather than being bound up (early in the expansion stroke) in the dissociation of combustion products. This effect is minor compared to the first two.

4- In a closed loop injection system, with EGR open, software is calibrated to inject less fuel in the cylinders

On diesel engines the improvement is smaller then on gas, but also occurs. .

I do not debate that blocking EGR reduces CBU. Therefore I do not judge as irrational your assessment on paying 10 bucks on a blocking plate instead of mantaining a clean intake via other measures. I just think the best economical decision would be buying a PFI gas car instead of a DI. Much cheaper engines and zero CBU!

If you have a solution for the emissions puzzle that eliminates EGR without negative collateral effects, start making money on it. All OEM's are desperate for a cheaper solution and removing parts will help
I'd be interested in reading the papers showing improvements in fuel consumption on a modern light duty common rail diesel engine when using EGR. The papers I've read show just the opposite. For example:

http://www.dieselnet.com/tech/engine_egr.php

The NOx emission benefit of EGR comes at a cost: other measures are usually required to avoid unacceptable increases in fuel consumption, emissions of PM, HC, and CO, engine wear and reductions in engine durability.

Then here is some direct measurements from my 335d operating in a back to back test with and without EGR. It shows quantifiable improvements to efficiency when not using EGR for highway operating conditions.

http://www.bimmerfest.com/forums/sho...0&postcount=60

Just a note on your point #1. Modern diesels do use throttle plates for controlling air flow in balancing the EGR. For example, here's a comparison of the EGR/Throttle behavior on my 335d.

http://www.bimmerfest.com/forums/sho...0&postcount=10

Also, the EGR recall that was performed was not, it seems, done to reduce CBU. Because it actually seemed to increase the use of EGR on my car. This is not helpful for reducing CBU. Here's data showing pre/post EGR recall behavior. Post recall the EGR was basically fully open most of the time... Yuck.

http://www.bimmerfest.com/forums/sho...3&postcount=67

And regarding the impact of NOx:

http://www.sciencedaily.com/releases...1030100022.htm

According to a new paper by Ott and Pickering in the Journal of Geophysical Research, each flash of lightning on average in the several mid-latitude and subtropical thunderstorms studied turned 7 kilograms (15.4 pounds) of nitrogen into chemically reactive NOx. "In other words, you could drive a new car across the United States more than 50 times and still produce less than half as much NOx as an average lightning flash," Ott estimated. The results were published July.
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      06-18-2014, 05:40 AM   #116
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Good news for anyone not under warranty who needs their CBU cleaned up and are in southern california. Offset motorwerks is doing CBU cleaning and has the attachment for the walnut blaster.
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Originally Posted by Offset Motorwerks View Post
Yes sir, we have all the tools here. However the price is more for the diesel since it is a longer process and a lot more gaskets have to be replaced at the same time. It is approx $750 with rental.
http://www.e90post.com/forums/showth...=940323&page=4
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      06-18-2014, 10:30 AM   #117
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wow. Great news and great price. Thanks.
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      06-18-2014, 11:18 AM   #118
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Quote:
Originally Posted by temporaptor View Post
Good news for anyone not under warranty who needs their CBU cleaned up and are in southern california. Offset motorwerks is doing CBU cleaning and has the attachment for the walnut blaster.


http://www.e90post.com/forums/showth...=940323&page=4
As time goes on let's hope the price drops even more as more shops get the equipment to do this...
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      06-18-2014, 12:38 PM   #119
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$750 seems like a pretty reasonable price assuming it includes the complete manifold and valve cover cleaning as well as the head cleaning
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      06-18-2014, 02:05 PM   #120
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Quote:
Originally Posted by Hoooper View Post
$750 seems like a pretty reasonable price assuming it includes the complete manifold and valve cover cleaning as well as the head cleaning
Sounds like a great price, I have said it before, I don't mind CBU as much as what it can do to the rest of the engine, fuel injectors, etc...
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      06-18-2014, 02:36 PM   #121
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2009 BMW 335d  [4.00]
Topic title should be changed to:

"Carbon build up! Here is how to delay it!"
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      06-18-2014, 06:14 PM   #122
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Any places in the St Louis area who can do the cleaning for a comparable price?
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      07-11-2014, 12:10 AM   #123
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Quote:
Originally Posted by GreekboyD
Topic title should be changed to:

"Carbon build up! Here is how to delay it!"
The only way to stop it is to prevent anything but clean filtered air through the intake.

I don't subscribe to the whole drive it like you stole it mentality. Sure it may reduce the EGR function under load for the brief time you are accelerating. During that high load you have higher revs and potentially more blow by recycled through the PCV. Now that the intake path is coated with an oily mist and during deceleration or coasting the EGR will kick in to mix some soot.

Meth obviously works here and so will EGR block and PCV catch can.
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