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Thinking about removing your FCV?
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=76414		 Page 1 of 3
Author:  kd4pbs [ Wed Aug 21, 2013 10:43 am ]
Post subject:  Thinking about removing your FCV?
This is basically my first post, and yes, I've read the Newbie guide, but don't feel the need to post some phpBB code to prove such... :wink:
I purchased a 2005 CRD late last month, and have been enjoying it and maintaining it. Did the timing belt, decided to replace the rockers while I was in there, did all kinds of other "mods" that have acronyms to confuse those that are not in-the-know, and have read most of the pertinent posts pertaining to the most stubborn and common problems our beloved CRDs exhibit.
One thing that strikes me as seriously flawed though, is the thought that we should remove the flow control valve in the intake. I'm sure that some people may think that it improves performance, removes some sort of perceived future point of failure, or is just some superfluous piece of equipment that will only tip the Jeep over due to increasing the center of gravity while rock crawling. What I haven't found (pardon if it has been mentioned) is the fact that the FCV (note, I *first* defined what the FCV acronym stands for so that future readers will not be confused :jester: ) is an important safety device. Have you ever seen a runaway diesel engine? Our FCV eliminates this possibility...
Food for thought, and thanks to everyone for making such a wonderful forum and warehouse of information on our KJs!
Author:  Jay ne Ohio [ Wed Aug 21, 2013 1:14 pm ]
Post subject:  Re: Thinking about removing your FCV?
The FCV does not prevent a runaway engine. It only closes for a second when the ignition key is turned off and then it reopens. This has been discussed many times in the past on this forum by people with more knowledge of this Jeep than I. However, I do have firsthand experience with a runaway engine and I can confirm that the FCV does NOT stop it from happening. I have three CRD's: one of them has the FCV unplugged with no ill effects, except for the check engine light being on.
Author:  kd4pbs [ Wed Aug 21, 2013 2:42 pm ]
Post subject:  Re: Thinking about removing your FCV?
So, repeatedly cycling the key from off to on, then quickly back off again will indeed cause each cycle to close the FCV and therefore quench the runaway condition, even if only a little at a time. Which would you rather have; a runaway diesel with a FCV that you can activate in one second intervals or a runaway diesel with nothing? I'll keep my FCV there, thanks :)
How about wire a switch to it to energize it in case of emergency? It would be a trivial matter that I'd think any forum member with the skills to wire a fog light could accomplish. This would totally nullify any argument that it can't be used to stop a runaway and the associated property and/or personal damage involved.
Author:  cerich [ Wed Aug 21, 2013 3:00 pm ]
Post subject:  Re: Thinking about removing your FCV?
how exciting, a fix for something that I don't think has ever been even reported on here...
Author:  geordi [ Wed Aug 21, 2013 3:14 pm ]
Post subject:  Re: Thinking about removing your FCV?
It does not have anything to do with preventing or stopping a runaway condition.

You seem to be resolved in your belief that it does, so I will stick to the facts:

Merely "cycling the key" will not cause the FCV to close a second or future times, because the single FCV closure is programmed as some type of "anti-shudder" shutdown device. The FCV will not close a second time with just a key cycle, because the ECU will not recognize that the engine is still spinning. It thinks the car is just in "on" mode, not running. The computer CANNOT DETECT A RUNAWAY with the way it is currently programmed.

The VW TDIs have this anti-shudder "feature" as a reason for a similar flap across the intake, and many of the TDI people also erroneously think that it will somehow prevent a runaway. There have been many more TDIs out there than CRDs, and comparatively many more TDI runaways... And NOT ONE was prevented or stopped by this flap in the intake.

Please do not spread disinformation about this. The FCV exists solely as part of the EGR system, and is programmed as such. The EGR runs on the CRD whenever the throttle is less than about 40%, so it runs a LOT. As you are slowing down / stopping, obviously the throttle is at idle, and the EGR will be at a "max flow" condition, where the FCV will be commanded at least partially closed, to maximize this exhaust gas flow. From this point, commanding it to close momentarily when a key-off is detected is an easy thing, and lends authenticity to the assertion that it is an "anti-shudder" device and not some emission control device that people would be more apt to mess with.

For reference: I have owned 2 TDIs that had this valve in place, and a CRD that also did. The shutdown on each was IDENTICAL before and after the devices were removed. No difference in shutdown time or "shudder" or roughness was seen.
Author:  papaindigo [ Wed Aug 21, 2013 3:22 pm ]
Post subject:  Re: Thinking about removing your FCV?
One report from a member who had a turbo failure and forgot to clean the excess oil out of his intercooler before restart result in worrisome high revs for a relatively short period of time. Zero, as far as I know, reports of similar events during a turbo failure due to dumping oil.

Whether the FCV valve would, even by cycling the key, have any effect on a runaway is a nice theoretical discussion but the fact remains that the FCV is not designed to nor is the engine software programmed to prevent a runaway.

Of course if the plastic gear that opens/closes the FCV has failed, as they often do, and the FCV is frozen in the open position all the key cycling in the world won't do anything.
Author:  kd4pbs [ Wed Aug 21, 2013 3:50 pm ]
Post subject:  Re: Thinking about removing your FCV?
Quote:
It does not have anything to do with preventing or stopping a runaway condition.

You seem to be resolved in your belief that it does, so I will stick to the facts:

Merely "cycling the key" will not cause the FCV to close a second or future times, because the single FCV closure is programmed as some type of "anti-shudder" shutdown device. The FCV will not close a second time with just a key cycle, because the ECU will not recognize that the engine is still spinning. It thinks the car is just in "on" mode, not running. The computer CANNOT DETECT A RUNAWAY with the way it is currently programmed.


So, if I turn the key off while driving down the highway, then back on, the ECM will believe the engine is not running, causing me to come to a complete stop so that the engine is not being driven through the transmission, put it in park or neutral, then hit the starter? Do tell. :roll:

Quote:
The VW TDIs have this anti-shudder "feature" as a reason for a similar flap across the intake, and many of the TDI people also erroneously think that it will somehow prevent a runaway.


Shudder? What are you talking about? Please show me where I mentioned anything about shutdown shudder, because while I might be long in the tooth, I can't remember writing anything about that.
Why didn't you reference my idea of adding an emergency shutdown switch to close the FCV? Are you contending that a throttle valve installed in the intake line, after the turbocharger will NOT shutdown a runaway diesel engine? Please do not post misinformation about a butterfly valve being mounted in the intake not being usable for an emergency shutoff valve.
Author:  kd4pbs [ Wed Aug 21, 2013 3:52 pm ]
Post subject:  Re: Thinking about removing your FCV?
papaindigo wrote:
Of course if the plastic gear that opens/closes the FCV has failed, as they often do, and the FCV is frozen in the open position all the key cycling in the world won't do anything.


Which only furthers my thoughts that maintaining a WORKING FCV is a good thing. Again, which would you rather have; a runaway with a FCV or a runaway without?
Author:  dirtmover [ Thu Aug 22, 2013 10:15 am ]
Post subject:  Re: Thinking about removing your FCV?
kd4pbs wrote:
Which only furthers my thoughts that maintaining a WORKING FCV is a good thing. Again, which would you rather have; a runaway with a FCV or a runaway without?


A runaway without.

My FCV is currently broken and if my engine runs away and self destructs it's next stop is the junkyard. I'd rather not scrap a few hundred dollars worth of new FCV in the process.

My point is that the FCV isn't going to prevent runaway. You need to cut the air completely and you're dreaming if you think that any amount of key flipping is going to achieve this.

With a properly disabled EGR system the FCV should remain open 100% of the time. Now, if someone can propose and prove out a means to manually wire in a kill switch then it may be worth considering. I'd still, however, make it a purely manual control by disconnecting it from the ECU in order to save the plastic gears.
Author:  flash7210 [ Fri Aug 23, 2013 8:15 am ]
Post subject:  Re: Thinking about removing your FCV?
If a run away occurs, maybe you could use these to pinch off a CAC hose.

Image
Author:  geordi [ Fri Aug 23, 2013 12:59 pm ]
Post subject:  Re: Thinking about removing your FCV?
You could do that... However, the time needed to stop the vehicle safely, throw it into neutral (in order to stop the car) and then jump out, run around to the hood, open the hood, grab the tool, and finally squeeze the hose off...

How many thousand RPMs above 5000 do you think the engine would have reached?

I would tend to think that the pistons would be coming through the hood before you got it open.
This topic is either a troll, or someone who is sadly lacking in specific knowledge about the CRD and its operations.

FYI: The intake flap on the TDI is known in their service manual and parts lists as a "Anti-shudder-device" and the part description says its purpose is to 'soften' the vibrations on engine shutdown. It does not do this, and it performs exactly the same way as the same device on the CRD - closes for less than a second on engine shut down, then releases.

6 posts, 4 in this thread, and you are a CRD expert? No, I don't think so. Thanks for playing though!
Author:  flash7210 [ Fri Aug 23, 2013 1:38 pm ]
Post subject:  Re: Thinking about removing your FCV?
I think a run away engine is very unlikely to happen.
But if a special clamp tool helps you feel better about it then keep one in your Jeep.

For me, making every effort to keep oil out of the intake (i.e. EHM) gives me piece of mind.
Author:  LMWatBullRun [ Fri Aug 23, 2013 2:10 pm ]
Post subject:  Re: Thinking about removing your FCV?
flash7210 wrote:
I think a run away engine is very unlikely to happen.
But if a special clamp tool helps you feel better about it then keep one in your Jeep.

For me, making every effort to keep oil out of the intake (i.e. EHM) gives me piece of mind.


X2. Runaways have happened and will continue to happen, and the way to avoid them is to keep oil OUT of the intake. If you are even more anal than I you might install a flap or gate valve with a cable and handle inside the driver's compartment to shut the engine off, but a little PM is a much less invasive solution.
Author:  Brianawd [ Fri Aug 23, 2013 4:50 pm ]
Post subject:  Re: Thinking about removing your FCV?
Runaway on a 4 stroke is really rare. Its manly a issue with old 2 stroke diesels.
Author:  Turbo Tim [ Sat Aug 24, 2013 12:23 pm ]
Post subject:  Re: Thinking about removing your FCV?
Also note that a “Runaway” condition you should be able to choke off the air before any real damage occurs to the engine.
Have any of you ever wondered why the RPM Red Line is only around 3 to 4K on a diesel? And why it is much higher on a gasser?
It is not because the engine crank and other rotating assembly cannot go that high; it is because of the Burn Speed of the fuel. Diesel fuel burns real slow compared to gas.
Author:  kjjet [ Sat Aug 24, 2013 7:15 pm ]
Post subject:  Re: Thinking about removing your FCV?
I do not had a FCV installed. None of the EGR system. That's all the FCV is used for (EGR). It is not a butter fly valve like in a Gasser. Take it out. and eliminate any problems.
Author:  kd4pbs [ Wed Aug 28, 2013 11:08 pm ]
Post subject:  Re: Thinking about removing your FCV?
geordi wrote:
This topic is either a troll, or someone who is sadly lacking in specific knowledge about the CRD and its operations.

Wow, what a pompous little sensored word you are. I mean, I have indeed seen some real forum know-it-all-but-nothings before in my 30 years of being online, but you take the cake, sir. My hat is off to you and your arrogance. I didn't catch the location, but I'd peg you for a yankee. [EDIT:] Ahh. I see you hail from the fine state of Georgia.
LOL.

Just a little update, but to all the nay-sayers on this issue, first let me preface this thought with the fact that the engineers of the 3508 750KW CAT powered (twin turbo) as well as the Kohler 750ROZD genset engines that I maintain must be idiots, because both of them put an emergency shutdown valve in the intake right between the turbocharger outlet and the intake valves. They must be pretty stupid as well.

Second, and perhaps it is due to the GDE Hot Tune that I just loaded, but I noticed that the FCV stays actively closed for around 10--15 seconds after the key is switched off. That would either indicate that GDE has thought of this exact scenario or that the OEM thought of this exact scenario. It would also indicate who in this "argument" has their heads up their asses, because if I remember correctly, someone stated that it only stayed closed for a second after shutoff.

Thank you so very much for letting me, as well as the rest of the people in the world know what a pompous, arrogant booty you are, as well as the fact that a perceived "newbie" has totally shown your pompous, arrogant booty up when it comes to the discussion at hand.

All I can say is that I am certainly GLAD I did not follow my gut instinct, which was to pay for a lifetime membership to this site because of what I thought were a bunch of like-minded individuals that had common sense. I appreciate the few true trolls that chimed in on this thread, and I appreciate to no end the fact that I have been shown your true colors.

Troll on, sensored word. Bite it.

Admin: Please delete me from your user database. It is clear that few here know their booty from their head. If only you knew who I am and what I have contributed to the GMECM tuning crowd in the past with several "hacks" on GM ECM models and .bin's over the years, you'd actually know this is not a troll. That being said, I've grown weary over schooling stupid morons like you, and bid you a fine FU.
:seuss: :mrgreen:
Author:  flash7210 [ Thu Aug 29, 2013 8:04 am ]
Post subject:  Re: Thinking about removing your FCV?
Dont let one member here ruin your entire LOST CRD experience.
This entire forum is full opinions and assumptions.
While most here have lots of experience with diesel engines, the Liberty CRD is unique and
unlike any other CAT, Cummins, International, or GM engines.
No one here is a VM Motori engineer or technician.
I dont think anyone here can really consider themselves an expert on this engine.

I'm sure you have lots of valuable experience that can be passed on to all the other CRD
owners here.
Who knows, maybe you will be able to solve the great mysteries behind turbo failure, rocker
arm failure, and head gasket failure that have created many, many long discussions on this
forum.
Author:  papaindigo [ Thu Aug 29, 2013 9:13 am ]
Post subject:  Re: Thinking about removing your FCV?
My my.

1. can a diesel engine runaway - yes
2. do some diesel engines have an emergency shutdown switch to kill a runaway - I don't know about all diesel generator engines but certainly those used in petroleum rich environments (ex. well drilling or refinery) are required to have such a switch. Do light duty diesel cars and trucks have such a switch; none that I know of or at least no switch designed for that purpose (I can speak for 1993 and 1994 and 1998 Dodge D250 Cummins, 1970's Mercedes turbo and non-turbo diesel and 05/06 KJ CRD). Do heavy duty commercial trucks have such a switch; I have no clue but there are clearly after market switches that can be obtained that probably could be installed on a light duty diesel car or truck.
3. does the CRD flow control valve butterfly function in such a manner as to act as an emergency shut down switch. In the context of a moving vehicle where the safety of turning off the ignition key is questionable the answer is no as there is no or no known engine hardware or software that will shut that valve automatically in a runaway nor is there a button on the dash, like on or near a generator, to do so. In the context of a stopped or nearly stopped vehicle will the CRD FCV butterfly stop a runaway. To the best of my knowledge the answer is no as the FCV, assuming it functions and the plastic gear that drives it can strip with no CEL, does not close long enough or perhaps tight enough.
4. can the FCV be forced or in some circumstances perhaps stop a runaway. Frankly I don't think anyone knows for 100% sure and short of forceably inducing a runaway to try and find out I'm not sure the answer can be determined.
5. are runaways an issue with CRDs. To the best of my knowledge none of the several folks that have blown a turbo while in motion have experienced a runaway. The only brief runaway that's been mentioned was where a blown turbo dumped a lot of oil into the intercooler, which was not cleaned, and a runaway occurred upon first start-up after a new turbo install.
6. are there folks operating with a affirmatively disabled FCV or one that's unknowingly not functional; yes. Are they having problems; apparently not. Is it a good idea to do so in the context of a hypothetical runaway; maybe/maybe not see above.

Bottom line. This is a nice theoretical debate comparing the possible function of the CRD FCV to indirectly (in the sense that it is not a design function) stop a runaway vs. the known function of a designed emergency shutdown switch on a diesel generator. As such I personally find it rather pointless as, absent the experiment mentioned above (not on my engine), there is no DATA relative to the CRD. If the OP or anyone else is worried about a CRD runaway then bit the bullet and install an after market emergency air block switch in the system and be done with it.
Author:  Hexus [ Thu Aug 29, 2013 10:40 am ]
Post subject:  Re: Thinking about removing your FCV?
Quote:
I mean, I have indeed seen some real forum know-it-all-but-nothings before in my 30 years of being online,


I really doubt you were connecting to ARPANET and and NSFNET back in the Mid 1980's, typically people who got online with DOS and UNIX have better typing and grammatical skills sir.

Commercial ISP's weren't even really available until the LATE 1980's, I know because I was there doing it.

Nice exaggeration though.
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