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  #37  
Old 08-01-2013, 09:47 AM
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Re: Horrible, I mean really bad, mpg on my hemi

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Originally Posted by greenwayer View Post
So I have had my 05 5.7 jgc for 3 months now and man the gas mileage is bad. According to the specs its supposed to get 14 city 21 why, but if I drive it like a v6 i will be lucky to get 11 mpg city. Normally I get around 10.5 with moderate throttle. If I step on it at almost every light I get 9 mpg. On a 60 mile hwy trip I average 17.5 mpg at a constant 65 mph. So is it running rich or is this normal? I mean I didnt buy this car for gas mileage, but this is srt bad without the power. I tried seafoaming it through the brake booster, gas tank, and the oil (didn't help) and I also changed the oil with mobil 1 synthetic 5w-20(also didn't help). I fill plus gas (89 octane) every time, which should also help gas mileage but it doesn't . No check engine light. What do you think?


Maybe change the temp sensor?
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  #38  
Old 08-01-2013, 10:55 AM
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Re: Horrible, I mean really bad, mpg on my hemi

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Originally Posted by greenwayer View Post
I did a seafoam treatment and replaced all the fluids with synthetics. Which sensors should I replace. My plugs seemed ok when I pulled them for a compression test.

Plugs typically don't look bad after 30k, but that is the service interval to put in new ones. If you have an 05, plug wires should be done at 60k too. If you did not get service records, there is no way of knowing how old the plugs are. If they have 35k or more, they will be the mpg culprit. Only put in OEM plugs. You can also replace the MAP sensor, PCV and EGR. For all three, it cost under $100 (not from dealer). The PCV takes a few seconds to install. MAP sensor is a bit more involved, since a post on the plastic intake has to be cut off. EGR is a 20 minute job; just don't follow the wrong instructions and pics posted in the how to section. Remove the intake, then remove the top EGR bolt, wiggle the EGR til loose, and rotate to the left all the way to expose the lower bolt, which is easy to get to now, and will come right out.
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  #39  
Old 08-01-2013, 07:50 PM
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When you say buy OEM plugs, and not from the dealer, where were you referring to? I need to order me up some

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Originally Posted by dmsfun View Post
It is senseless to debate this; drive one that corners and you will be humbled very quickly. Even when new the stock WK suspension is terrible at cornering. Considering that these suspensions get worn out in as little as around 40k miles, your 2WD is a marshmellow needing new shocks, springs, isolators, sway bar bushings, and end links. An upgraded suspension like mine is a totally different vehicle than a new stock WK, and corners hard, under total control.
All 4wd systems are not alike as well. The QDII system is very advanced, has front and rear limited slip differentials along with a ltd slip transfer case, so it will transfer power to the wheels with the most traction automatically. 100% of the power can go to just one wheel if that is the only wheel with traction. In a rainstorm, I can floor it from a stop and it will just fly with no wheelspin. Your 2WD has an open differential, the worst for cornering.
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  #40  
Old 08-01-2013, 09:38 PM
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Re: Horrible, I mean really bad, mpg on my hemi

IMO, you don't really need "OEM" Champion plugs. I've been running NGK LZTR4A-11, Stock No. 5306 plugs in my 05 Hemi LX (for about 7 years) and my 06 Hemi WK (for almost 4 years) and have never had the slightest problem. Also, the NGK's are a better quallity plug to begin with.
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  #41  
Old 08-01-2013, 11:18 PM
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Re: Horrible, I mean really bad, mpg on my hemi

Damn man that's low mpg. I get 10-12mpg and have plenty of fun while doing it. On the hwy I get 14-16 depending how much my foot is in it. Good luck on finding a solution!
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  #42  
Old 08-03-2013, 12:48 AM
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Re: Horrible, I mean really bad, mpg on my hemi

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Originally Posted by 5280SRT8 View Post
Damn man that's low mpg. I get 10-12mpg and have plenty of fun while doing it. On the hwy I get 14-16 depending how much my foot is in it. Good luck on finding a solution!
It sucks man, our mpg is as bad, and you have a supercharged srt. I am pissed. I should at least be getting 14-15
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Old 08-03-2013, 08:40 AM
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Re: Horrible, I mean really bad, mpg on my hemi

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Originally Posted by jeepgcoman View Post
IMO, you don't really need "OEM" Champion plugs. I've been running NGK LZTR4A-11, Stock No. 5306 plugs in my 05 Hemi LX (for about 7 years) and my 06 Hemi WK (for almost 4 years) and have never had the slightest problem. Also, the NGK's are a better quallity plug to begin with.
I've used OEM Champions for 89k in my 06 WK and about to purchase another set. If people want to go with another, good luck. Some might work OK, others not but improved performance over OEM is not going to happen. Champions will always work, are US made and the #1 choice of the fastest cars in racing.. used by four out of the last five NASCAR Cup Champions, the last six NHRA Top Fuel Champions and also won 400 Formula 1 races - more than all other plug manufacturers combined.
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  #44  
Old 08-03-2013, 05:36 PM
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Re: Horrible, I mean really bad, mpg on my hemi

Well, let's see, I don't drive a NASCAR vehicle (wish I did though), I don't drive a Top Fuel Dragster (wish I did though), and I don't drive a Formula 1 vehicle (wish I did though), but I do have a Hemi WK that I do drive on the street every day. Do you really think all these professional racers go down to Auto Zone and pick up the plugs for their vehicles? Hell no!! They're special plugs, made specifically for special purposes. I base my opinions on actual experience using and working on vehicles (both stock and race) and aircraft that utilized Champion (and other brands) spark plugs. In my experience (going way back before they had so many to choose from), Autolite's were the worst (don't know if they even make them any more), AC's were the next best (don't know if they still make them either), and Champions were the best of the three. Bosch plugs weren't used to much, except in German vehicles.....IMO, they're not very good anymore either. Years ago I used to use Champions, and they were pretty good back then. In today's world there are many more choices, with many of them being much better than the Champions.

To give you an idea, there is a thread on another Jeep forum, dealing with quite a few Hemi stalling/misfire issues, that has been going on since January 2011, and currently is 68 pages long and has over 1000 responses. Near the center of this discussion is the Champion/Mopar 570's vs. "regular" Champion 570's. Walt, the Physics Professor, has access to some cool test equipment and has tested both. Here, in part, is what he said:
"OK. Here's what I got with the LCR meter for the Champion 570's, Champion 3570's, and MOPAR OEM spark plugs. Some of these were difficult to get and replicate after multiple attempts. Readings are in Henry's, nano- or pico-Farads, and kilo-Ohms.
I'm thinking the effect on the RC, LC, and RL constants changes the response in the secondary circuit. The surface capacitance across the center and ground electrodes will change because the diameter of the Champion 570 and 3570 (platinum) center electrodes is much different."

And here's the most recent entry from, jeffC3210:
"Kevin, I concur with you. I had just used the Champion plugs from Advanced auto about six months ago, and had major stalling issues. I went to the dealer and bought the OEM Mopar plugs a couple of weeks ago (two numbers/letters on box) (4-SPRE14MCC4) & (RE14MCC4) with the numbers 570 on the spark plug boxes inside. (They had the exact same numbers on the plugs but wern't Mopar OEM Copper Plus) Oh, and the tops were black on the new OEM's. The 570 number isn’t on the outside of the four pack box itself, but it is on the end of each individual plug box in the four packs. I also moved the ground wire that goes to the passenger wheel well to the (ECU?) I think. I took it away from a metal line it was going over and attached it to rubber hoses away from any metal. Also removed the three inch piece of aluminum heat shield tin off the (heater hose?) at the rear of the passenger side head, and replaced it with a piece of cut rubber hosing about the same length. (All three of these were suggested on this list, and I thank you guys.) I wish I would have done one thing at a time, but I can tell you now that the dam thing runs just like the day I bought it, and I’ve got ninety-thousand miles. There are no more stalls, (I was getting at least two a week) and it pulls so cleanly now. I can tell the difference in the way it feels for sure. When I touch the peddle when in too high of a gear, I used to say it seemed low on power and would have to downshift to get it to pull, but not now, it’s running and pulling super strong again!!! I’m almost a hundred percent sure that it was just the plugs. So try those first and let us know."

So, to use part of your quote, "If people want to go with another (replace another with Champions), good luck." I still say, these days there are many brands that are far superior to Champions. In the end though, TO EACH HIS/HER OWN. Whatever floats your boat.
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  #45  
Old 08-03-2013, 08:13 PM
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Re: Horrible, I mean really bad, mpg on my hemi

Quote:
Originally Posted by jeepgcoman View Post
Well, let's see, I don't drive a NASCAR vehicle (wish I did though), I don't drive a Top Fuel Dragster (wish I did though), and I don't drive a Formula 1 vehicle (wish I did though), but I do have a Hemi WK that I do drive on the street every day. Do you really think all these professional racers go down to Auto Zone and pick up the plugs for their vehicles? Hell no!! They're special plugs, made specifically for special purposes. I base my opinions on actual experience using and working on vehicles (both stock and race) and aircraft that utilized Champion (and other brands) spark plugs. In my experience (going way back before they had so many to choose from), Autolite's were the worst (don't know if they even make them any more), AC's were the next best (don't know if they still make them either), and Champions were the best of the three. Bosch plugs weren't used to much, except in German vehicles.....IMO, they're not very good anymore either. Years ago I used to use Champions, and they were pretty good back then. In today's world there are many more choices, with many of them being much better than the Champions.

To give you an idea, there is a thread on another Jeep forum, dealing with quite a few Hemi stalling/misfire issues, that has been going on since January 2011, and currently is 68 pages long and has over 1000 responses. Near the center of this discussion is the Champion/Mopar 570's vs. "regular" Champion 570's. Walt, the Physics Professor, has access to some cool test equipment and has tested both. Here, in part, is what he said:
"OK. Here's what I got with the LCR meter for the Champion 570's, Champion 3570's, and MOPAR OEM spark plugs. Some of these were difficult to get and replicate after multiple attempts. Readings are in Henry's, nano- or pico-Farads, and kilo-Ohms.
I'm thinking the effect on the RC, LC, and RL constants changes the response in the secondary circuit. The surface capacitance across the center and ground electrodes will change because the diameter of the Champion 570 and 3570 center electrodes is much different." Why do you suppose that is, when they're supposedly the same plug???

So, to use part of your quote, "If people want to go with another (replace another with Champions), good luck." I still say, these days there are many brands that are far superior to Champions. In the end though, TO EACH HIS/HER OWN. Whatever floats your boat.
So what do you think champion 7570 double platinum?
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Old 08-03-2013, 08:15 PM
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Re: Horrible, I mean really bad, mpg on my hemi

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Originally Posted by dmsfun View Post
I've used OEM Champions for 89k in my 06 WK and about to purchase another set. If people want to go with another, good luck. Some might work OK, others not but improved performance over OEM is not going to happen. Champions will always work, are US made and the #1 choice of the fastest cars in racing.. used by four out of the last five NASCAR Cup Champions, the last six NHRA Top Fuel Champions and also won 400 Formula 1 races - more than all other plug manufacturers combined.
Havent they been replaced with e3's?
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Old 08-04-2013, 04:12 PM
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Re: Horrible, I mean really bad, mpg on my hemi

Greenwayer, you can give the platinums a try, but be aware that many of the 05's (in particular) were very sensitive to the type plugs installed. If they work, great. If not, you get to buy some other type/brand. Usually, when you go to a platinum plug when a copper core is recommended, you'll have to open up the gap a little, because it takes less voltage to fire the platinums. If you run the platinums, and have a loss of power, using the stock copper plug gap may be the culprit.
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Old 08-04-2013, 04:17 PM
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Re: Horrible, I mean really bad, mpg on my hemi

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Originally Posted by jeepgcoman View Post
Greenwayer, you can give the platinums a try, but be aware that many of the 05's (in particular) were very sensitive to the type plugs installed. If they work, great. If not, you get to buy some other type/brand. Usually, when you go to a platinum plug when a copper core is recommended, you'll have to open up the gap a little, because it takes less voltage to fire the platinums. If you run the platinums, and have a loss of power, using the stock copper plug gap may be the culprit.
I was just thinking the platinums might be a better plug, but I didnt know the coppers are recommended. Actually the coppers are cheaper, I have no problem using those. I'd rather stick with something thats tested and has proven results. So champion copper plus 570?
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