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Popular Mechanics on EGR issues
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Author:  kjfishman [ Fri Jul 21, 2006 2:44 pm ]
Post subject:  Popular Mechanics on EGR issues
cut and pasted from http://www.popularmechanics.com/blog/au ... 22231.html


A Little More Info On Our Jeep Liberty CRD


CRD=Common Rail Diesel



Okay, as promised here's what we found out from DaimlerChrysler: the regional techs replaced the entire throttle body on the Liberty's little Italian-built 2.8-liter four-cylinder turbodiesel because of either 1. the possibility of temperature swing-induced leakage at the clamping areas, or 2. possible stripped teeth on a motor-driven, spring-loaded air management valve integral with the throttle body.

We believe that's a fair assessment because 1. No matter how many diagnostic trouble trees a tech completes, sometimes he just has to start thinking past his nose and let his black magic experience take over, and 2. this is the first application of this powertrain in a U.S.-spec Liberty so there are practically no past service issues to draw on. Plus, the Check Engine light is staying off, which likely means they nailed it.

The EGR valve apparently was never a real issue, but was replaced twice because the engine management system kept spitting out codes that led Manhattan Jeep down that line of diagnostics. Hopefully, they'll know better next time.

True, we're not strapped for a daily driver the way the typical Jeep Liberty CRD owner might have been under the same circumstances. So it's easier for us to say this was a well-handled, professional service experience. But we also didn't get any special treatment. Sometimes fixing modern cars just isn't that straightforward.--Ken Juran
Author:  kjfishman [ Fri Jul 21, 2006 3:36 pm ]
Post subject:  question?
"2. possible stripped teeth on a motor-driven, spring-loaded air management valve integral with the throttle body. "

Is the the EGR Flow control Valve?
Author:  Goglio704 [ Fri Jul 21, 2006 3:37 pm ]
Post subject: 
Sounds like it to me.
Author:  oldnavy [ Fri Jul 21, 2006 5:12 pm ]
Post subject:  Re: question?
kjfishman wrote:
"2. possible stripped teeth on a motor-driven, spring-loaded air management valve integral with the throttle body. "

Is the the EGR Flow control Valve?
Whoever wrote the article or report is a little confussed on their terms and what does what on a diesel.

Quote:
1. the possibility of temperature swing-induced leakage at the clamping areas
Is really funny, if they are refering to EGR Flow Control Valve as it seems they are. Only thing that would cause is a loss of boost pressure and at shutdown a trend toward running on or shudder. This problem would only be caused by improper install either at factory or by a tech who had it off and reinstalled. Very, very unlikely and the code would be low boost pressure if code is set.

Quote:
2. possible stripped teeth on a motor-driven, spring-loaded air management valve integral with the throttle body.


Very likely the problem if we are talking about the EGR Flow Control Valve, I have heard someone mention here on forum that they were told that first version had plastic gears and they failded easly were being replaced by ones with metal teeth. The only reason this Valve keeps being called a throttle body is it is similar in looks to a TB on a gasser, but that is where it ends as it does not doing anything a throttle body would on a gasser such as fuel or air flow control. It only serves one purpose and that is to stop the engine without the shuddering or after-run and to help eliminate the posibility of runaway engine if you were to blow a hole in a piston or or have total seal failure of the turbo seals. Failed turbo seals being the most common on these turbos on as on the VW's, and with our automatic the only way to stop the engine if you were driving down the highway/street would be to have that Flow Control Valve to close when you shut of the ignition switch otherwise the engine blows before you could get stopped, hood open and get something to block the air intake.
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