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Thread: Just Changed Spark Plugs and EGR Valve (Hemi)

  1. #1
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    Default Just Changed Spark Plugs and EGR Valve (Hemi)

    Wow, those plugs were horrible. They had 70k miles on them I guess. I saw where the new ones should be gapped at .045 so that is what I left them at (factory Champion 570's). The ones I took out were gapped at .060. No wonder my gas mileage sucked.

    This was on an 05 Hemi..

    I also changed the EGR Valve to. Not to bad..

  2. #2
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    Haha I wonder if the had ever been changed? They're supposed to be changed every 30K miles.
    -Frank the Tank-



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    There is no telling. Glad they are changed now though!

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    Quote Originally Posted by totty View Post
    Wow, those plugs were horrible. They had 70k miles on them I guess. I saw where the new ones should be gapped at .045 so that is what I left them at (factory Champion 570's). The ones I took out were gapped at .060. No wonder my gas mileage sucked.

    This was on an 05 Hemi..

    I also changed the EGR Valve to. Not to bad..
    Where did you get your EGR Valve from? I can't find one local. I have only found one at rock-auto.

    I have the spark plugs ready to go. I am just trying to source an EGR valve now.
    2008 JEEP GRAND CHEROKEE OVERLAND 4X4
    5.7 HEMI QDII
    2" OME MD : 265/70/17 ON MOABS : AFE STAGE II
    KICKER AUDIO : WEATHERTECH MATS : ROLA RACK
    4XGUARD 12-BOLT DIFF GUARD : BT CATCH CAN

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    Got mine at autozone. Still sounds like a woodpecker under the hood every now and then. Just drove from winchester, ky to pigeon forge, tn and got about 16mpg. Hell of a lot better than it has been!
    Sitting in a cabin over looking the mountains, drinkin beer! Woohoo!

  6. #6
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    Quote Originally Posted by totty View Post
    Got mine at autozone. Still sounds like a woodpecker under the hood every now and then. Just drove from winchester, ky to pigeon forge, tn and got about 16mpg. Hell of a lot better than it has been!
    Sitting in a cabin over looking the mountains, drinkin beer! Woohoo!
    That's funny. My Autozone and O'reilys both said they don't carry one. Oh well, I'll keep looking around.

    Enjoy the mountains!
    2008 JEEP GRAND CHEROKEE OVERLAND 4X4
    5.7 HEMI QDII
    2" OME MD : 265/70/17 ON MOABS : AFE STAGE II
    KICKER AUDIO : WEATHERTECH MATS : ROLA RACK
    4XGUARD 12-BOLT DIFF GUARD : BT CATCH CAN

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    Still only getting 16 mpg??? At what speed? How much air do you run in the tires and are they stock sized tires? Have you checked the PCV (~$25) Valve, behind the throttle body butterfly and intake runners for caked on oily crap, and have you ever changed the MAP sensor (also ~$25), or at least inspected it? They can also contribute to poor economy. Also, what kind of fuel are you running...octane and if it has ethonol, how much?
    06 GCO, Dark Khaki, QDII, Siped Toyo STII 265/295 R20 tires, Tinted Ft and WS Visor, Flashing, Hi 3rd Brake Lt, MDS "ON" Lt, Airtab Vortex Gens, Cbn Air Filter, Wheelskins Steer Wheel Cover, Debadged, DashHawk Veh Info Display, Fumoto Drain Valve, Billet Tech Catch Can, Chopped EGR Tube, Custom LX SRT-8 CAI W/Additional Air Inlet and K & N Air Filter, Sonnax Trans Line Press Booster, Superchips Tuner W/Adv Trans Tuning App., Diablosport Tuner, Cust Tubular Headers w/3 in Magnaflow/Xlerator AP Exh Sys, Bilsteins, SRT Lwr Springs/Sway Bars, Cust Color Engine Cover, SRT8 front/rear bumpers, FRI Sidewinder Cam w/6.1 valvetrain, SLP UD Pulley, BBK 90mm T-Body, SOS coils using .060 in. spark plug gaps, 20X9 and 10 in. SRT Rep. wheels.

  8. #8

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    I can't believe how good your fuel economy is on the 5.7L HEMI.

    I get 10 MPG city and 14 MPG highway.

    What can I do to improve this? How do I know if the MDS is working?
    2005 WH Limited Navigator 5.7L HEMI
    __________________________________________________ _____________
    QDII | Superchips | Metallic black | 10% metal tint | Headrest DVD's | MDS indicator light | Catch can | Fumoto valve | Custom skid plates

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    I haven't changed the map or the pcv. I have been running an 87-93 mix. When i get about half tank low on 87 i fill up with 93. My last tank last night was all 93.
    I am running a 3.5" rk lift with 265/70/17 duratrak's

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    Briteway, you can add the MDS "ON" light so you can tell when it's active, or you can purchase something like a DashHawk, which has a PID that tells you. How many miles is on your 05? Do you have the maintenance history for it? If so, tell us everything you know.....type of oil/when changed, plugs, EGR valve, PCV valve, spark plug wires, MAP sensor, make/size tires/tire pressure, when last alignment/tire wear pattern, diff./Xfer case fluid change, trans. fluid/filters change, type/grade fuel used, etc. There is a ton of things that can adversely affect economy. Most folks that drive semi sensibly (I am not always one of those) gets ~12-14 mpg all in town, ~14-17 mpg in mixed city/rural/highway driving, and ~17-22 mpg on the highway. If you always drive like you stole it, or drive many short (~1-5 miles) trips, you're probably not too far off at 10 mpg.

    Totty, unless you've had your odometer recalibrated, with that size tire on your mileage will be less than normal. Maybe check it against some mile markers on the highway to verify how much. Your tires are more than 2 in. greater in diameter than the stock ones. Also, a lift usually adversely affects mileage too.

    Jeepinxj3, I don't understand why O'Reilly's doesn't have it. That's where I got mine. Can they order it for you? Maybe try online or Napa.
    Last edited by jeepgcoman; 02-14-2011 at 07:02 PM.
    06 GCO, Dark Khaki, QDII, Siped Toyo STII 265/295 R20 tires, Tinted Ft and WS Visor, Flashing, Hi 3rd Brake Lt, MDS "ON" Lt, Airtab Vortex Gens, Cbn Air Filter, Wheelskins Steer Wheel Cover, Debadged, DashHawk Veh Info Display, Fumoto Drain Valve, Billet Tech Catch Can, Chopped EGR Tube, Custom LX SRT-8 CAI W/Additional Air Inlet and K & N Air Filter, Sonnax Trans Line Press Booster, Superchips Tuner W/Adv Trans Tuning App., Diablosport Tuner, Cust Tubular Headers w/3 in Magnaflow/Xlerator AP Exh Sys, Bilsteins, SRT Lwr Springs/Sway Bars, Cust Color Engine Cover, SRT8 front/rear bumpers, FRI Sidewinder Cam w/6.1 valvetrain, SLP UD Pulley, BBK 90mm T-Body, SOS coils using .060 in. spark plug gaps, 20X9 and 10 in. SRT Rep. wheels.

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    I keep a spreadsheet of every fuel fill up. (date, total miles, gallons, price per gallon) i keep a running tab of my "corrected" mileage and it confirmed a 15mpg round trip and i came back in a 15-20mph headwind. I have my gps to confirm the mileage difference.
    If anyone is interested in my spreadsheet, let me know. Its great for keeping track of what your monthly cost to operate your vehicle is. Quite helpful when looking for another vehicle or upgrades and what they would cost you per mile and how long it would take to re-coup the cost!
    In other wise a good way to keep the wife informed of your calculated or not so calculated thoughts!

  12. #12

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    Quote Originally Posted by jeepgcoman View Post
    Briteway, you can add the MDS "ON" light so you can tell when it's active,
    I'm interested in doing this. So, then, how would one do that?

  13. #13
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    JeepsFTW, I came up with this mod. about 5 years ago over on the LXForum for the 300C, Charger and Magnum RT's with the Hemi engine. Here's my thread over there, under my screen name, magnuman: http://www.lxforums.com/board/showth...5813#post55813

    The wiring pinouts are the same, but the job on the WK is easier than on the LX, because there is a nice firewall access right behind the PCM on the WK. Just route the wire in behind the glovebox and run it to where you want the light to be. Just make sure you "tap" the correct wire, as there are two brown/light blue wires in that plug. The pix here shows where I mounted mine on the WK. On the LX (with the on/off switch) I've never turned it off, so, IMO, it's not worth using a switched light. If you have any more questions, feel free to ask.
    Attached Images Attached Images
    06 GCO, Dark Khaki, QDII, Siped Toyo STII 265/295 R20 tires, Tinted Ft and WS Visor, Flashing, Hi 3rd Brake Lt, MDS "ON" Lt, Airtab Vortex Gens, Cbn Air Filter, Wheelskins Steer Wheel Cover, Debadged, DashHawk Veh Info Display, Fumoto Drain Valve, Billet Tech Catch Can, Chopped EGR Tube, Custom LX SRT-8 CAI W/Additional Air Inlet and K & N Air Filter, Sonnax Trans Line Press Booster, Superchips Tuner W/Adv Trans Tuning App., Diablosport Tuner, Cust Tubular Headers w/3 in Magnaflow/Xlerator AP Exh Sys, Bilsteins, SRT Lwr Springs/Sway Bars, Cust Color Engine Cover, SRT8 front/rear bumpers, FRI Sidewinder Cam w/6.1 valvetrain, SLP UD Pulley, BBK 90mm T-Body, SOS coils using .060 in. spark plug gaps, 20X9 and 10 in. SRT Rep. wheels.

  14. #14

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    Looks like I have my project for the weekend!

    It's hard to tell when it's going in and out of MDS. It says only between 40 - 60, but I see the RPM's move around at lower speeds too. I'm assuming that this is the MDS kicking in, but this light will let me know for sure.

    Thanks!

  15. #15
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    Damn! Lol love my 4.7! 13 city 19 highway at 65mph with 33" tires @ 40 psi
    WK Sold! Spare tire with 95% thread for sale. Also have one quick disco made to work with SL.

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    That is another thing. I was running my tires at 33 psi cold.

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    When working correctly, the MDS will begin kicking in at ~16=17 mph. On my LX I can keep it on (really light throttle) from ~17 mph all the way up to ~75 mph, even through the shifts. There are some "dead" spots (~36-40) where it won't come on if it's not already on. Usually you just have to "goose" it, or move the speed up or down just slightly. The good thing is that, once you have the light, you can begin to learn the activation parameters and adjust your driving style to maximize its use. Here's an article by a guy over on the LXForum that worked on the R and D for the MDS. It will give you an idea about the technology and work that went into setting it up. Also, be aware that the tuners (DS and SC) enhance the MDS operation and one of the primarily activation parameters isengine load....more power/torque equals more MDS time. The post is by, magnumrt:

    "The MDS system is much more complicated than most people realize. The design of the system took MANY more years than you may think, I actualy started working on this system back in 01 in some DC concept vehicles. Trust me, there were many issues to try and get it right. One of the requirements for this system was the electronic throttle controll. When you deactivate 4 of the 8 cyls, you get about a 50% reduction in air requirements meaning that when you hold your foot on the gas at 25%, in V8 mode, the throttle blades are at about 25% open, but when you go into 4cyl mode, we need to immidiatly adjust the throttle to about 15% throttle without YOU fealing it. This is an extreamly complex algorithm and is QUITE heavy in closed loop feedback with the MAP sensor, Crank/Cam position sensors, Input/output shaft speed sensors, etc. Also when you move from 8-4cyl there is obviously less vacuum being drawn by the motor. Lower vacuum to the MAP sensor is translated normaly as a higher load on the motor, but you need the PCM to realize that this is not the case at this particular moment. Now, as far as your question of why the motor doesnt stay in MDS longer to give you better fuel mileage? That is another compicated story that has been tuned quite extensively to give the best overall gas mileage without issues. When the lifters cut out and trap exhaust gasses in the cyl, that gas acts as a spring to keep the motor from wasting energy while the inactive pistons are going up and down. This gas begins to loose it's energy because the cyls will tend to leak a bit (through the rings and through the valves). The motor needs to re-initialize the cyl to allow the spent gases to escape. Now, the question is, why do you not re-initialize right away to save more gas? Simple, you gotta keep the engine's temperature equal so that you dont have 4 cyls working at a different opperating temperature than the others. The 4 cyls that are not firing will get cold as well as the valves, intake runners and specificaly the exaust pipes. Cold exhaust pipes dont flow as well as hot pipes and therefore you get an imbalance in those 4 cyls when running in V8 mode. The timing has been optomized for all these conditions to occur as transparently as possible. Extending the MDS time or frequency would end up creating more problems than are apparent to most.

    So yeah, in conclusion.... It aint easy to do, there wont be any way for quite some time for you to increase the amount of time the MDS turns on for the simple fact that the design aint simple ;-) Not to mention the strategy has been developed to be as optimal as it could be. Trust me, the goal was fuel economy and transparency, TONS of time and effort went into making it as good as it can be."
    06 GCO, Dark Khaki, QDII, Siped Toyo STII 265/295 R20 tires, Tinted Ft and WS Visor, Flashing, Hi 3rd Brake Lt, MDS "ON" Lt, Airtab Vortex Gens, Cbn Air Filter, Wheelskins Steer Wheel Cover, Debadged, DashHawk Veh Info Display, Fumoto Drain Valve, Billet Tech Catch Can, Chopped EGR Tube, Custom LX SRT-8 CAI W/Additional Air Inlet and K & N Air Filter, Sonnax Trans Line Press Booster, Superchips Tuner W/Adv Trans Tuning App., Diablosport Tuner, Cust Tubular Headers w/3 in Magnaflow/Xlerator AP Exh Sys, Bilsteins, SRT Lwr Springs/Sway Bars, Cust Color Engine Cover, SRT8 front/rear bumpers, FRI Sidewinder Cam w/6.1 valvetrain, SLP UD Pulley, BBK 90mm T-Body, SOS coils using .060 in. spark plug gaps, 20X9 and 10 in. SRT Rep. wheels.

  18. #18

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    Quote Originally Posted by jeepgcoman View Post
    How many miles is on your 05? Do you have the maintenance history for it? If so, tell us everything you know.....type of oil/when changed, plugs, EGR valve, PCV valve, spark plug wires, MAP sensor, make/size tires/tire pressure, when last alignment/tire wear pattern, diff./Xfer case fluid change, trans. fluid/filters change, type/grade fuel used, etc. There is a ton of things that can adversely affect economy.
    I have 41,600 miles on mine, serviced regularly. I'm not sure of changing any of the sensors, at least my mechanic never suggested nor have I seen it on any of the invoices. I think he used 5W-30 oil.

    Tires have never been replaced, front two are almost worn out so I'm thinking of getting a new set of 4 and an alignment.

    I'm not sure about the transmission, t/case and diffs fluids change.

    I generally use 87 fuel and from time to time 91.

    Most folks that drive semi sensibly (I am not always one of those) gets ~12-14 mpg all in town, ~14-17 mpg in mixed city/rural/highway driving, and ~17-22 mpg on the highway. If you always drive like you stole it, or drive many short (~1-5 miles) trips, you're probably not too far off at 10 mpg
    LOL, I drive sensibly, trying to increase fuel economy and always battling with this but from time to time, I'll give it a squirt, can't help it, it's a HEMI (but not as if I stole it, LOL).

    Quote Originally Posted by jeepgcoman View Post
    ...I came up with this mod. about 5 years ago over on the LXForum for the 300C, Charger and Magnum RT's with the Hemi engine. Here's my thread over there, under my screen name, magnuman: http://www.lxforums.com/board/showth...5813#post55813
    This is awesome, you must be pretty switched on . Thanks for that. I'll get around it one weekend and try it out. It should give me peace of mind when I see the MDS is working. They should've built this light in in the first place.

    Quote Originally Posted by jeepgcoman View Post
    When working correctly, the MDS will begin kicking in at ~16=17 mph. On my LX I can keep it on (really light throttle) from ~17 mph all the way up to ~75 mph, even through the shifts. There are some "dead" spots (~36-40) where it won't come on if it's not already on. Usually you just have to "goose" it, or move the speed up or down just slightly. The good thing is that, once you have the light, you can begin to learn the activation parameters and adjust your driving style to maximize its use.
    I think I'll have fun with this mod

    Also, be aware that the tuners (DS and SC) enhance the MDS operation and one of the primarily activation parameters isengine load....more power/torque equals more MDS time.
    I actually just received the SC tuner in the mail.

    I think I'm gonna have to do a major service with my GC, probably myself so I know definitely what's been changed and see how the fuel economy goes after that.

    I'll post back with results once everything's completed.
    2005 WH Limited Navigator 5.7L HEMI
    __________________________________________________ _____________
    QDII | Superchips | Metallic black | 10% metal tint | Headrest DVD's | MDS indicator light | Catch can | Fumoto valve | Custom skid plates

  19. #19

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    Quote Originally Posted by AcidCold View Post
    Damn! Lol love my 4.7! 13 city 19 highway at 65mph with 33" tires @ 40 psi
    My 4.7 is a dog in the lower RPM's. MPG is around 11 city and 16-17 highway. I live in the Seattle area so we have hills to conquer.
    2006 4.7L Limited Quaddra-Drive II
    255/70/17 Revo 2's
    Ronin 2 Wheels
    Bilstein's Front/Rear
    Rough Country 2" Lift/Level
    Flowmaster 50 muffler
    K&N FIPK intake
    Powerwire
    Frontt/rear window tint
    Painted front grill
    Powdercoated diamond mesh grill
    Hell 500ff's behind the grill
    Superchips

  20. #20
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    I've had two 4.7's one was an overland. Give me my hemi and a gas truck any day!!

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