2 EGRs?

ibHenry · **Posted:** Sat Sep 10, 2011 6:05 pm

ive been looking through the FSM and if im not mistaken it says theres an EGR valve on the left side of the motor under the intake manifold and then it says theres one located just above the turbo. so i went out and looked at my crd and i do actually see both that it talks about, so my question is if im not mistaken and there actually is two, why?

CATCRD · **Posted:** Sat Sep 10, 2011 10:28 pm

There is no EGR valve on the turbo side of the motor. The actual EGR valve is down on the driver's side, kind of below the fuel filter. It's hard to see. The other one in the intake is called the EGR flow control valve, or FCV. It's a motorized throttle plate that restricts fresh air flow to increase exhaust gas flow at light loads. Basically a system to force your engine to eat its own crap.

geordi · **Posted:** Sat Sep 10, 2011 10:43 pm

Both those parts are design disasters, and WILL fail often and expensively. The best thing you can do for your engine is to take the FCV off the intake elbow and unscrew the big butterfly disc from the center of it. Now, it can never close again and fork up your engine. It has NOTHING to do with a 'soft shutdown' or doing anything at all to prevent a possible engine runaway. It COULD, but the requisite programming and sensors don't exist in our CRDs. It is ONLY there for the emissions control crap.

The second thing you should do is a combination of SEGR device to keep the computer happy, GDE tune to keep you happy with your performance, and block-off plate for the EGR tubes themselves to ENSURE that you and your engine remain happy.

EAB · **Joined:** Tue Sep 06, 2011 9:39 pm **Posts:** 141

ibHenry wrote:

ive been looking through the FSM and if im not mistaken it says theres an EGR valve on the left side of the motor under the intake manifold and then it says theres one located just above the turbo. so i went out and looked at my crd and i do actually see both that it talks about, so my question is if im not mistaken and there actually is two, why?

I think the one on the turbo is an actuator?

ibHenry · **Posted:** Sun Sep 11, 2011 2:07 pm

Thank-you for your help, so let me make sure I have this straight, if I do the EHM, ORM, and remove the butterfly plate from the elbow valve,(are you 100% sure it will not prevent a runaway engine), the only other thing to do is check for CEL codes on a regular basis, I really can't afford the flash programing or SEGR, is this correct? Also I am coming up to 100,000m service, I am planing on replacement of timing belt, associated pulleys and tensioners, including the water pump and thermostat, while the front is apart I will flush out my intercooler which I'm sure has a ton of oil in it. A warning should go out to those that have oil on their MAP's, it means that the intercooler is pretty full of oil and can cause a runaway engine condition.

geordi · **Posted:** Sun Sep 11, 2011 3:08 pm

You are close, but a little high on the fear scale based on the experience from this board.

There isn't enough oil passed by the CCV into the intake to cause a runaway condition. As long as you have the CCV connected to the intake, oil mist will travel through the intake and by simple process of continuous contamination... Cover everything in there including the MAP. Where this becomes a problem is that the oil is corrosive to the original factory boost hoses, and rots them out from the inside. Same for the airbox-to-turbo hose which is usually shredded at the turbo inlet. The second problem with this design is the EGR valve, allowing in (and forcing, with the FCV) the engine to inhale its own exhaust soot. Soot is pure carbon, and is NOT BURNABLE. It is also highly abrasive. Just the thing you want against your shiny cylinder walls, right? The soot touches the oil in the intake and instantly sticks, is covered with more oil, collects more soot... Rinse and repeat. This mud that coats the MAP sensor is the real thing to be concerned about, not that the MAP has an oily coating. The oil will eventually dissipate to a minimal level if left alone after installing an EHM.

Each and every one of the CRDs out there started off with this same design, and many of them that aren't on this board are STILL running around with it. Have you heard on the news about runaway diesels? Neither have I.

Now, on to the FCV and quelling any fears there. The function of the FCV is a throttle plate (That no diesel for 100 years has EVER needed for operation!) that greatly restricts the incoming clean air to force an increase in EGR flow. The computer has no way of monitoring EGR actuation, there isn't a sensor there. Equally, there is no sensor to monitor FCV function. The ONLY sensors the engine has are air sensors, and there are three of them. There are actually TWO MAP sensors. One is the main MAP that we all know about on the back of the intake. The second is the "Mercedes Logo Sensor" on the side of the airbox. The third is the MAF sensor on the intake tube. The only checks that the computer can do against the EGR or FCV themselves is whether they are plugged in or not. Thats why simply unplugging either one electrically won't work - You get codes and limp mode b/c the computer knows you are messing with something and the nanny system is programmed to force compliance. Screw that!

The function of the Mercedes sensor is not entirely clear, but I suspect it is part of the nanny system for the EGR b/c if you mess with it or the wires break (and they are pretty weak) then your reward is a persistent limp mode with no codes. Highly annoying.

Since the only sensors the computer can look at to check the function of the EGR as part of the nanny-system are these air sensors... The computer looks for a drop in the airflow across the MAF when it tells the EGR to open. Does it see it? Ok... All is well. No? Close the FCV. Does it see it? Yes... Fine. No? Close more, if no change... Limp mode and code for insufficient EGR flow. That is why the book lists these items together - They are linked in function, and cannot be used separately by the computer.

When you shut the engine off, you sometimes hear a buzzing noise from the fuel-filter area of the engine. This is the FCV motor being forced BACKWARDS into fully-open by the giant spring that the motor must force against. The default position is OPEN. When you turn the key off (the first natural instinct of a person with a runaway engine) the power is REMOVED from the FCV and it will completely open. There is no way to control when it closes outside of the EGR programming.

The VW design has had something similar for years on the USA models... I do not believe that the German versions have this. They called it a "soft shut down" device, and it was controlled by engine vacuum. Cute... Except when you cut the engine, vacuum instantly evaporates! That's why you hear your A/C duct doors opening to the default defrost position after shutting off your engine too! The flap on my VW never closed at shutdown, I watched it (before I removed the EGR there) and it did NOTHING at shut-down. That means that is part of the EGR system there too. Ick.

Hopefully this answers your questions about the function of this system. Its all based on a design of being more complicated than it needs to be... To enforce compliance and prevent people doing exactly what we are doing - increasing the lifespan of our engines and removing destructive useless components.

warp2diesel · **Posted:** Sun Sep 11, 2011 3:19 pm

ibHenry wrote:

Thank-you for your help, so let me make sure I have this straight, if I do the EHM, ORM, and remove the butterfly plate from the elbow valve,(are you 100% sure it will not prevent a runaway engine), the only other thing to do is check for CEL codes on a regular basis, I really can't afford the flash programing or SEGR, is this correct? Also I am coming up to 100,000m service, I am planing on replacement of timing belt, associated pulleys and tensioners, including the water pump and thermostat, while the front is apart I will flush out my intercooler which I'm sure has a ton of oil in it. A warning should go out to those that have oil on their MAP's, it means that the intercooler is pretty full of oil and can cause a runaway engine condition.

With an oil separator, either the Provent or one made from 2" PVC pipe stuffed with steel wool like mine will help keep oil mist out of the intercooler. I have a drain line going back to the sump so I don't have to empty it out every oil change. Use a non waxy synthetic oil like Amsoil or Rotela T-6 and your Provent filter won't tend to clog up.
Anyone have idea what size the serial number fonts on the beans the Bean Counter Engineers who won't put a good oil separator on a diesel engine :?:

Enquiring minds want to know :ROTFL:

CATCRD · **Posted:** Sun Sep 11, 2011 6:29 pm

[quote="geordi]
When you shut the engine off, you sometimes hear a buzzing noise from the fuel-filter area of the engine. This is the FCV motor being forced BACKWARDS into fully-open by the giant spring that the motor must force against. The default position is OPEN. When you turn the key off (the first natural instinct of a person with a runaway engine) the power is REMOVED from the FCV and it will completely open. There is no way to control when it closes outside of the EGR programming. [/quote]

You have that backwards. When you turn the key off it snaps shut for a few seconds, then flips open to its default position. This has everything to do with smooth shutdown, as the difference in engine shake is obvious when your FCV fails open.

geordi · **Posted:** Sun Sep 11, 2011 7:23 pm

I disagree, b/c I've actually taken the thing apart. The spring holds it open, it doesn't have the ability to "snap" anything while pushing against that force. The motor might already have it partly closed b/c at idle is when the engine will be trying to do most of the EGR cycles anyway other than light throttle in gear. The electric motor would need to react much faster than it does, especially since the reaction time of the key being moved to off, and the engine stopping is within a 1/10th of a second. The power cuts to the electric motor, and the spring forces it backwards.

As for the "soft shutdown" part of it, as I said before, they claimed thats what the device was for on the VW TDI too. The engine shutdown is exactly the same before and after. An engine that is shutting down will always rock a bit back and forth, b/c of simple physics - The gyroscope of the pistons / crankshaft is changing speed, which destabilizes the engine itself. Causing a momentary lack of air pressure isn't going to stop that.

Sir Sam · **Posted:** Sun Sep 11, 2011 8:00 pm

geordi wrote:

I disagree, b/c I've actually taken the thing apart. The spring holds it open, it doesn't have the ability to "snap" anything while pushing against that force. The motor might already have it partly closed b/c at idle is when the engine will be trying to do most of the EGR cycles anyway other than light throttle in gear. The electric motor would need to react much faster than it does, especially since the reaction time of the key being moved to off, and the engine stopping is within a 1/10th of a second. The power cuts to the electric motor, and the spring forces it backwards.

As for the "soft shutdown" part of it, as I said before, they claimed thats what the device was for on the VW TDI too. The engine shutdown is exactly the same before and after. An engine that is shutting down will always rock a bit back and forth, b/c of simple physics - The gyroscope of the pistons / crankshaft is changing speed, which destabilizes the engine itself. Causing a momentary lack of air pressure isn't going to stop that.

The difference between a working FCV at shutdown and a not working one is very noticeable in the last final shudder.

geordi · **Posted:** Sun Sep 11, 2011 8:21 pm

Ok, then either I've never had a working FCV, or I can't feel the difference between when my engine is running and it isn't. B/c I seriously don't notice anything "rough" about the shutdown when I turn the key off. The engine stops. It isn't like the body of the car shakes like a wet dog, and I haven't seen where the engine violently does that either with the hood up.

I've got two of the things, one that is in my engine right now and de-disced... The other came from the original engine and has 60k miles on it. I don't know if it functions, but maybe for fun I'll plug it in and watch the action as I shut the engine off. If it "snaps" shut, then I will report back here as such and stand corrected. Even with the GDE tune and the SEGR, that single function is supposedly still in place for this thing.

CATCRD · **Posted:** Sun Sep 11, 2011 10:07 pm

Maybe "snap" is too strong a word, but it does close immediately at shutdown. I've had two of them go bad now, and I know what it's like. The behavior you describe a few posts above is that of a failed FCV.

ibHenry · **Posted:** Mon Sep 12, 2011 10:27 am

If your HVAC doors are moving after shut down you have a bad check valve, and just because you havn't heard of one doesn't mean it hasn't happened. I had a Cummings do it after the customer failed to mention his turbo was leaking oil, it was an experience I will never forget. The intercooler had oil in it. :grim:

2 EGRs?

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