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Unread 06-28-2012, 10:52 AM   #16
meep
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clean the whole throttle body. Mine looked clean to the eye but I removed it and painstakingly went through it and i kid you not it immediately gave me back almost a full mpg. I do not understand why. It *looked* clean. I also blew out the TPS, no canned air just took it apart and blew off dust by mouth. looked fine to start with. Makes no sense to me as I said it wasn't dirty per my opinion to start with, but I was chasing other problems so I cleaned it to check that off the list.

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Unread 06-28-2012, 11:08 AM   #17
06WKHEMI
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Quote:
Originally Posted by 90grandoneer
The Exhaust Gas Recirculation Valve (EGR), is located on the front, passenger side head and has an insulated tube going to the intake manifold. If this valve malfunctions, some of the symptoms are, erratic, almost stalling idle, low speed surging, and poor performance and fuel economy. Mine went bad (with a code) at ~54K miles. When is the last time the plugs were changed? What type of plugs were installed? Has the backside of the throttle body butterfly been cleaned? Do you have a catch can? If not, IMO, it is a must on the Hemi. Take the air tube off at the throttle body and manually (with engine off) open the butterfly. Shine a light in and examine the backside of the butterfly and the intake plenum behind it. Look for caked on oil crap, and puddling in the plenum. Guaranteed you'll have it, and it will probably be real bad. This crap may affect the proper operation of the MAP Sensor, which in turn will tank the fuel economy. When's the last time the PCV Valve was changed? Once all of this is sorted out and repaired/replaced, reinstall the DS Tuner. It should work real well....it does on mine.
Will it always throw a code if you have egr issues? My idle seems ok but i get surging at low speeds especially when cold but so far no CEL
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Unread 06-28-2012, 12:13 PM   #18
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Quote:
Originally Posted by fourtrax450r View Post
i understand but im saying you can achieve much better. people who are okay with 12 mpg when they can achieve 16 are lazy. i was that guy and then a month ago i said no...i want better gas mileage lol
You have to take into consideration where your driving. You cant just say everyone should get 16 mpg because I do. I drive 99.9% city and rarely can go over 1 mile without stopping mostly multiple times. If I go somewhere and get on the highway or even back roads with limited stopping I can get up into the 16-18s but stop and go driving kills gas mileage.
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Unread 06-28-2012, 01:08 PM   #19
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Quote:
Originally Posted by Static83
better then my 11 on my 4.7
I'm getting the same on my 4.7 lol
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Unread 06-28-2012, 01:50 PM   #20
Shafer57
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Quote:
Originally Posted by 90grandoneer View Post
The Exhaust Gas Recirculation Valve (EGR), is located on the front, passenger side head and has an insulated tube going to the intake manifold. If this valve malfunctions, some of the symptoms are, erratic, almost stalling idle, low speed surging, and poor performance and fuel economy. Mine went bad (with a code) at ~54K miles. When is the last time the plugs were changed? What type of plugs were installed? Has the backside of the throttle body butterfly been cleaned? Do you have a catch can? If not, IMO, it is a must on the Hemi. Take the air tube off at the throttle body and manually (with engine off) open the butterfly. Shine a light in and examine the backside of the butterfly and the intake plenum behind it. Look for caked on oil crap, and puddling in the plenum. Guaranteed you'll have it, and it will probably be real bad. This crap may affect the proper operation of the MAP Sensor, which in turn will tank the fuel economy. When's the last time the PCV Valve was changed? Once all of this is sorted out and repaired/replaced, reinstall the DS Tuner. It should work real well....it does on mine.
Good info thanks. Never cleaned the TB but have been meaning to, and planned on replacing the EGR to play it safe. Any particular wipe to use? Microfiber for less fibers sticking to it then getting sucked in? etc.
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Unread 06-28-2012, 02:25 PM   #21
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06WKHEMI, no it will not always throw a code. That is probably not the issue with yours, as the EGR is not functioning when the engine is cold. If you have these symptoms with a warm engine, then maybe yes.

When mine was failing I got a light. I cleared it, and then started monitoring EGR commanded and error rates with my DashHawk. The "commanded" settings were rapidly changing and were all over the place, sometimes to unrealistic %ages. The PCM tries to accomodate these commands, and has the "error rate" (correction) chasing and trying to catch up with the commands. When operating normally, the commands are somewhat predictable, usually ~50-60% on the highway, and the error rate is almost always close to or at zero. Since I didn't monitor mine before it failed, I can only assume that they start failing over time (like spark plugs), and may not be noticed until it throws a code. If you're getting any of the symptoms I listed above, and have 50K+ miles on it, that would be one of the first places I'd looked. I'll probably now make mine a "time change" item at either 50 or 60K intervals. I'll do that because mine began throwing the code on a highway trip, and I found it annoying. Once it's been changed and you cut the one bolt a little, it's a 30 minute, $40-50 job. Well worth a little preventative maintenance, IMO. Hope this helps you a little.

Shafer57, on yours I'd start with the easy, inexpensive stuff first, doing one thing at a time and see if it makes any difference. If the plugs haven't been changed, that might be the first place to go, followed by the TB cleaning and changing the PCV Valve, adding a catch can, and then on to the EGR, unless you have symptoms. Then I'd move it up the list. A couple other things....if your driving has a lot of stop and go, your mileage isn't really that bad. No matter what mods. you've done, it still takes a certain amount of power to get the nearly 5000 lb. WK moving again. Another factor is how long you sit at the stops. On some local "long" signals (2 min. or more), I'll shut mine off...if I saw it change to red. With all my mods., in town I still get ~12-14 mpg, but then again, I can't keep my foot out of it either. One other thing, you may want to increase your tire pressure a little. The recommended pressure is not always the optimum pressure for tire life or economy. I run mine at 40 PSI front and 38 PSI rears, and rotate them every 6000 miles. My tires are also siped.
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Unread 06-28-2012, 02:44 PM   #22
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Thanks 90 im picking up an egr and a pcv after work so ill have something to do tonight :-)
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Unread 06-28-2012, 04:31 PM   #23
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Quote:
Originally Posted by Shafer57 View Post
.... Any particular wipe to use? Microfiber for less fibers sticking to it then getting sucked in? etc.
When I do mine, it's an old, clean cotton t-shirt, isopropyl alcohol, and q-tips for the tight spots. Doesn't scratch anything.

Tip: I cut a new wooden paint stirrer to about 5" long and use it to CAREFULLY prop open the throttle body butterfly while I clean it. Adjust it perpendicular to the axis of the butterfly shaft and the butterfly will stay open as you clean, expecially around the shaft penetrations (with a q-tip).

Listen to 90grandoneer. Sage maintenance advice.
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Unread 06-28-2012, 06:51 PM   #24
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When you do your EGR Valve, be sure to cut about 3/16 in. (the unthreaded part) off the end of the bottom bolt. It'll make the job easier next time. In addition to cutting mine, I also ground the lip off the head of the bolt to get even a little more clearance. Also, don't completely remove the tube going to the intake. If you do, you risk ruining the seal that goes into the intake and it'll cost you a trip to the dealer. After loosening the tube, I just gently rotated it out of the way and secured while I changed the valve.

This is just my recommendation for the PCV Valve. I always install mine with the hole facing the rear. If it faces front, it gives any oil a direct path to the intake. My goal is to slow it down a little. Don't think it says to do it that way anywhere, and I don't know if it really helps. Just my thoughts. Also, IMO, you should get a catch can ASAP, so you won't have that oil contamination cycling through your engine. My last trip (~1350 miles) passed ~2.0-2.5 oz. into the can. For my vehicle, that means it may be time to look at the PCV valve again.
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Unread 06-28-2012, 07:54 PM   #25
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Thanks alot guys. All of the above listed things will be taken care of shortly Everything adds up, and I never expected a prius out of the hemi, but was curious what to start with to keep it at it's prime.

I'm going to poke around and figure out which catch can to go with, and how to install (beginning to end). And a beginning to end of the EGR replacement.
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Unread 07-01-2012, 09:13 AM   #26
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Here's how I spent my Saturday. I still have moe to do (i.e. check/replace valves/sensors), but I'm really glad I caught this post. Mine was really nasty - looked like bedliner.

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Unread 07-01-2012, 12:56 PM   #27
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These tips are great, I have an 07 5.7 Overland that I'd like to squeeze a few more MPGs out of.

I will do the throttle body, EGR, PCV and MAP sensors this week - it's been stalling a lot too. I have 67k miles, and I'm not sure how old the plugs are, so maybe a set of those is in order too.

Is there a standard catch can that everyone uses? Would removing the roof rack cross bars help any? Would a chip/tune make a difference on mileage if I could keep my foot out of it afterwards? How about synthetic oil? Any other tips known to work?
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Unread 07-01-2012, 05:55 PM   #28
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AA-Train, I think that's about the worst TB I've seen. Did you see any puddling in the plenum, or just the caked on crap? You can bet that your valves and piston tops look like that too. How many miles on yours? What's your fuel economy like? Last tune up at how many miles? If you have more than, say 60K on it, and maintenance is unknown or not current, you may want to also do the following, if they haven't already been done, expecially if your fuel economy is real bad:
--SeaFoam it. Many say this works great. I've never needed to do this, as I have a catch can and my intake is clean.
--New copper core spark plugs if they haven't been changed in a while. I use NGK LZTR4A-11, Stock No. 5306 on both my Hemi's.
--After SeaFoam (or other carbon remover/fuel injector cleaner) change the O2 Sensors. See this thread: http://www.jeepforum.com/forum/f67/o...rimer-1182446/
--Change the MAP Sensor
--For sure install some sort of catch can.
--Install a new PCV Valve.
--Install a new EGR Valve.
--Drive it hard for a while. It helps blow and keep the carbon out. I drive mine hard much of the time, but I keep all my maintenance current and do preventative maintenance on anything that is not quite up to snuff.

A couple side notes regarding carbon buildup:
--Years ago a buddy and I had taken his wife's Rustang somewhere, and coming back he hammered it. It promptly stalled and wouldn't start. Final diagnosis.....CARBON all came loose from the combustion chambers and stuck several valves open. Fix.....pull the heads, clean carbon from everything, and do a valve job while it's apart. Wife used to do nothing but putt around town, and do a lot of idling.
--A friend's mother had a 68 Chevy Caprice with a 409 engine and always used to putt it around town. After just a few months it would start to miss. I took it up on the Interstate and did a half dozen WOT runs with it. You should have seen the white hot carbon coming out the exhaust. Idle would improve, but new plugs were needed too. After that, she'd give it to me every few months to "fix the idle". Repeat procedure, sometimes with plugs, sometimes without.

DanV410, many of us use the Billet Technology catch can. It's a little spendy (~$100), but the quality is well worth it. There are others available for as little as $25-30, but generally, you get what you pay for. Like AA, if your mileage is still not up to par after you do your maintenance, you may also want to consider O2 Sensors. Cost of all 4 is ~$120. Installation on a stock exhaust, is a pain in the arse though....but doable.
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Unread 07-01-2012, 05:57 PM   #29
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Quote:
Originally Posted by DanV410 View Post
.... it's been stalling a lot too. I have 67k miles, and I'm not sure how old the plugs are, so maybe a set of those is in order too.

Is there a standard catch can that everyone uses? Would removing the roof rack cross bars help any? Would a chip/tune make a difference on mileage if I could keep my foot out of it afterwards? How about synthetic oil? Any other tips known to work?
1. Do a search for charlesrshell and 2007 5.7L HEMI's stalling. Long, but interesting thread. 2007 model year seems to be the common thread (pun intended).

2. Billet Technology oil catch can. Make your own L-bracket for mounting (~$2.50 at Home Depot).

3. 5W-20 full synthetic oil (e.g., Mobil-1, Castrol Syntec, etc) seems to work best in mine.

4. Mobil-1 85W-140 full synthetic differential lube (4 qts total) for the front and rear differentials. Add 4-oz. MOPAR friction modifier to each axle if you have QD-II (no substitute that I'm aware of).

5. MOPAR NV245/247 Transfer case fluid (2 qts total - no substitute here either).

http://www.wkjeeps.com/wk_maintenance.htm . That will get you started.

90grandoneer took off the cross bars on the roof rack. Don't remember if it made a difference.
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Unread 07-01-2012, 06:04 PM   #30
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If I don't win that 392 '5.7L' stroker at Carlisle, it is probably time for me to deal with installing a catch can.. and maybe getting a Fastman remachined TB (I am starting to think I have some actuator/TPS issues). And replacing the EGR.

But still, even without that, I have to work at it to get down below 12.5MPG. That takes some "spirited driving" for me, normal backroads foot-in-the-throttle-body for me is around 13.

...tom
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