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Old 09-26-2010, 11:59 AM
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EGR System Observations

Quite a few of the 5.7 Hemi WK owners have experienced problems with the EGR system. Symptoms are, at a minimum, erratic idle, low speed surging, and poor performance and fuel economy. I decided to keep a closer eye on the EGR system operation after I got an EGR MIL that subsequently ended with the change of the EGR valve.

Since I have two (LX and WK) 5.7 Hemi powered vehicles, both equipped with a DashHawk (http://www.dashhawk.com/) Vehicle Information Display, I decided to see if I could find any differences in operation between the two.

I installed a new EGR valve in the WK at about 54000 miles. The LX has about 45000 miles and never had the valve changed. After I got my first light on the WK, I reset it and it returned about 2 days later. I then started monitoring the EGR system, %age commanded vs. %age error. Both fluctuated very rapidly and wildly, achieving unrealistic (more than 100%) numbers on both items. After changing the EGR valve, the commanded vs. error %ages were realistic and somewhat predictable. There is still movement, but not as rapidly. The continuous changing is due to the PCM's ongoing changes to engine settings based on throttle opening, engine temperature, timing, etc.

On the LX I have noticed that the %age commanded vs. error is slightly more under all conditions than with the new valve on the WK. I am thinking that the valves, with age/mileage, begin to lose their effectiveness and responsiveness, eventually to the point that it throws a MIL. I think Walt is on to something when he says these should be changed at a set interval. The price of the valve is only about $50 and, after the first change, it is only about a half hour job. I am going to keep an eye on the system in the LX, and see if it progressively gets worse. I will probably add it to my scheduled maintenance schedule for about 48000 miles, even though I can monitor its operation. Being that it appears to lose its effectiveness slowly over time, one would not normally be aware that this COULD be the cause of some of the problems listed above.
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Old 09-26-2010, 01:17 PM
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Re: EGR System Observations

Excellent write up with great information. I can relate to some of the symptoms you are referring to in such situations: when I use my remote start, the engine starts and then I get an immediate surge in RPM before the engine begins to idle down. I also feel surging under acceleration intermediately but not all the time. I have the Diablo tune and I can't get nearly the MPG others are reporting. I've checked all the basics from tires to spark plugs and it still seems poor by comparison.

Is this something I can read with the Diablo tuner? I've yet to have a MIL show up but I feel that the EGR valve *could be on it's way out and if you've replaced yours at 54k and I currently have 65k, I wouldn't be hesitant to replace it.
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Old 09-26-2010, 03:39 PM
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Re: EGR System Observations

Blackpepper, I too have a DS tuner, and it does not give you the capability to monitor the EGR. I also have the Superchips tuner, and it doesn't either. You'll need something like the DashHawk to monitor it.

I don't know what it is with the EGR valve that causes this, but I can speculate since I tore my old one apart, and it is really a basic electomagnetic solenoid controlling the valve (pintle) opening by varying application voltage. I think the big culprit is probably the duty cycle life of the unit is being approached when things start to act up. Heat also has to be a factor. IMO, a number of things could be going on to cause this. The spring could loose its designed tension, the valve and seat could be compromised (leaking), and more likely, the solenoid is slowly dying. One more theory of mine is that the type of driving one does could affect valve longevity. Predominantly in town driving will cycle the valve many more times than driving on the highway. I am also curious to see how the aftermarket valves will work over time. Will they fail sooner, last about the same, or longer. Time will tell.

To answer your question, With your mileage, I would change it if you are experiencing some of the symptoms. There are several "how to's" on these forums that give good instructions. I was able to get mine out without moving the alternator or cutting the original bolt. Definitely try that first. It will require a little prying and force, but I didn't damage anything when I got mine out. On the new bottom bolt, just be sure to cut about a quarter inch off of it, chamfer the end real good so you don't cross thread it going in, and I also belt sanded the small lip off the head of the new bolt. First time takes about 1 1/2 to 2 hours. Subsequent times should take no more than about a half hour. One other caution....don't remove the tube from the intake manifold unless you have a spare seal in your possession. I just rotated and secured mine out of the way during the R and R. Hope this helps.
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Old 09-27-2010, 11:20 AM
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Re: EGR System Observations

id like to know what we need to do to completely remove it. ive done it on some other cars before. all you need is a block off plate.
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Old 10-02-2010, 09:11 PM
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Re: EGR System Observations

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Originally Posted by tig488 View Post
id like to know what we need to do to completely remove it. ive done it on some other cars before. all you need is a block off plate.
Thought about that myself. Might not be as simple on the WK as on earlier engines.

There is a "device" sold to cure the HEMI tick. It seems to be nothing more than a $20 gasket with a reduced flow area for exhaust gas recirculation. It throws a code on some of them.
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Old 10-05-2010, 08:35 AM
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Re: EGR System Observations

Did you replace the valve yourself? I think I recall looking at mine and it seemed like it might be an easy replacement but I can't recall.
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Old 10-05-2010, 05:59 PM
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Re: EGR System Observations

I replaced mine myself. The first time it is kind of a pain, because the lower bolt is hard to get out. It hits on the alternator just has it starts to clear the head. There are some "how to's" on some of the forums that give good guidance. I was able to get the bolt out without messing with the alternator or cutting the old bolt. Also, didn't remove the tube.....just tied it out of the way. If you pull the tube, you risk damaging/breaking the seal that goes into the intake manifold. If you must remove it, be sure you have a replacement seal on hand, just in case. After the initial R and R, any subsequent R and R's should take about 1/2 hour, as long as you've cut about a 1/4 in. off the bottom bolt.
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Old 12-01-2011, 12:08 AM
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Well I have been monitoring the EGR percents and error percents with my dashhawk. At idle the numbers are % is .078 and error % is 0.00, Driving faster the Com% is all over the place , But the error % is sometimes - or + numbers, But the thing that is making think the the EGR valve is going bad, Is when I get that hemi hestinant at 35-40 going up a incline the numbers go back it CMD % .078 error 0.00, So is my EGR going bad I got 40k on the jeep. So could you guys check your numbers see what you are getting.

Thanks

Chris
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Old 12-01-2011, 01:09 PM
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Re: EGR System Observations

Chris, it doesn't sound like it's going bad. What you're getting at idle (also when cold) is the valve not being actuated.....hence the .078%. At cruise you should be getting probably 50+% and slightly fluctuating (at constant throttle on level ground) with fairly low error plus and minus correction %ages. You may get a couple "spikes" on error %ages. If it were real bad, both commanded and error %ages would be wildly and continuously fluctuating to quite unrealistic numbers. You'd also notice surging, especially at slower speeds, when this is happening. Anytime you change throttle settings, or driving environment (wind, incline/decline, etc.) the EGR settings will change.
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Old 12-10-2011, 08:49 PM
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Re: EGR System Observations

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Originally Posted by jeepgcoman View Post
Chris, it doesn't sound like it's going bad. What you're getting at idle (also when cold) is the valve not being actuated.....hence the .078%. At cruise you should be getting probably 50+% and slightly fluctuating (at constant throttle on level ground) with fairly low error plus and minus correction %ages. You may get a couple "spikes" on error %ages. If it were real bad, both commanded and error %ages would be wildly and continuously fluctuating to quite unrealistic numbers. You'd also notice surging, especially at slower speeds, when this is happening. Anytime you change throttle settings, or driving environment (wind, incline/decline, etc.) the EGR settings will change.
X2. Mine is closed at idle. Varies at other speeds, but it goes from a commanded change to its new position quickly and EGR error percent goes to ~0%. Top opening that I recall is 65% and typically ~50-55%.

Interesting that it will go to 0% under low-load MDS operation with cruise control on. As load increases, the opening increases (as it should). Exhaust gas recirculation cools down the combustion temperature to reduce oxides of nitrogen (NOx) and that happens under higher load.

Mine went bad at 45K miles. Now at 73.6K miles and it continues to function acceptably.

My 2 cents. Hope it helps.
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Old 12-19-2011, 08:53 AM
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Re: EGR System Observations

Quote:
Originally Posted by jeepgcoman View Post
I replaced mine myself. The first time it is kind of a pain, because the lower bolt is hard to get out. It hits on the alternator just has it starts to clear the head. There are some "how to's" on some of the forums that give good guidance. I was able to get the bolt out without messing with the alternator or cutting the old bolt. Also, didn't remove the tube.....just tied it out of the way. If you pull the tube, you risk damaging/breaking the seal that goes into the intake manifold. If you must remove it, be sure you have a replacement seal on hand, just in case. After the initial R and R, any subsequent R and R's should take about 1/2 hour, as long as you've cut about a 1/4 in. off the bottom bolt.

Definitely replace the EGR if you have 50k or more. They only cost $39 at most parts stores for the 5.7, and are simple to replace. I read about so many people cutting the bolt and buying a shorter one, etc.. For anyone that has basic mechanical skills, it is very easy to replace the 5.7 EGR without having to go through all this.
Remove the top right bolt, then rotate the EGR all the way to the left. THe bottom bolt is now very easy to get to and easily clears the alternator. Same way for installation; took me about 20 minutes total (I have a CAI so that saves time).
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