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  #73  
Old 09-01-2013, 08:35 PM
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Re: Horrible, I mean really bad, mpg on my hemi

Ok, so today I did some datalogging and the average air/fuel commanded equivalence ratio was .99 which is right around 14.6/1. This included a wot run which brought the minimum down to .73 for a very short time. Otherwise the air/fuel equiv ratio is 1.
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  #74  
Old 09-02-2013, 09:26 AM
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Re: Horrible, I mean really bad, mpg on my hemi

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Replaced the spark plugs with campion 570s and now I am down to 7 mpg city. Is it really this bad?

Something is askew, as I drive mine with a heavy foot and am getting nearly double that, 12.5 city, and HWY driving logs over 20 mpg at 65 mph, with 90k on the odometer. I just put in new OEM plugs last week after exactly 30k on the old set, and it made a noticable difference in WOT and MDS 4 cyl operation is totally seamless.
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  #75  
Old 09-02-2013, 11:15 AM
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Re: Horrible, I mean really bad, mpg on my hemi

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Originally Posted by dmsfun View Post
Something is askew, as I drive mine with a heavy foot and am getting nearly double that, 12.5 city, and HWY driving logs over 20 mpg at 65 mph, with 90k on the odometer. I just put in new OEM plugs last week after exactly 30k on the old set, and it made a noticable difference in WOT and MDS 4 cyl operation is totally seamless.
Yes that's what I am thinking. I am having to fill the thing up with a full tank of gas every 3 days or so. Thinking I may just trade it in if I can't figure it out.
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  #76  
Old 09-02-2013, 11:21 AM
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Re: Horrible, I mean really bad, mpg on my hemi

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Originally Posted by dmsfun View Post
Something is askew, as I drive mine with a heavy foot and am getting nearly double that, 12.5 city, and HWY driving logs over 20 mpg at 65 mph, with 90k on the odometer. I just put in new OEM plugs last week after exactly 30k on the old set, and it made a noticable difference in WOT and MDS 4 cyl operation is totally seamless.
Yes that's what I am thinking. I am having to fill the thing up with a full tank of gas every 3 days or so. Thinking I may just trade it in if I can't figure it out. Also one thing to note is while I was changing my plugs I cracked the pcv hose(hose from oil spout to air filter) this shouldn't affect anything right?
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  #77  
Old 09-03-2013, 09:16 AM
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Old and new plugs
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  #78  
Old 09-09-2013, 03:28 PM
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Re: Horrible, I mean really bad, mpg on my hemi

Ok getting tired of filling up the tank every 3 days after only 130 miles. How do I know if I should replace the egr valve?
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  #79  
Old 09-10-2013, 05:21 PM
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Re: Horrible, I mean really bad, mpg on my hemi

When it is really bad, the EGR valve will trip a DTC. Although it is possible for it to need changing without the CEL coming on.

The most common symptoms are erratic idling and stalling at slow speeds, but it all depends on whether the valve is stuck open or closed or somewhere in between.

It's a cheap easy part to replace. If you think that it might need doing, you might as well replace it...though I doubt it is the root of your problem (but certainly wouldn't hurt).
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Old 09-11-2013, 12:15 AM
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  #81  
Old 09-14-2013, 08:41 AM
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Re: Horrible, I mean really bad, mpg on my hemi

I would go ahead and replace the EGR and MAP sensors as together they are under $100. (not from dealer) To replace the EGR, don't follow the pics and instructions posted in the how to section. It is very easy; just remove the intake, remove the 2 egr tube bolts on pass side, remove the top bolt on EGR, then wiggle it to loosen, and rotate all the way down to left, (pass side) so the lower bolt is now easily accessible and comes right out. To do the MAP sensor, you will have to cut off the plastic post on the intake to insert the new MAP sensor. Having done them, I could do the job in 30 minutes for both now.
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  #82  
Old 09-15-2013, 12:22 AM
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Re: Horrible, I mean really bad, mpg on my hemi

Quote:
Originally Posted by dmsfun View Post
I would go ahead and replace the EGR and MAP sensors as together they are under $100. (not from dealer) To replace the EGR, don't follow the pics and instructions posted in the how to section. It is very easy; just remove the intake, remove the 2 egr tube bolts on pass side, remove the top bolt on EGR, then wiggle it to loosen, and rotate all the way down to left, (pass side) so the lower bolt is now easily accessible and comes right out. To do the MAP sensor, you will have to cut off the plastic post on the intake to insert the new MAP sensor. Having done them, I could do the job in 30 minutes for both now.
Ok, I took the map sensor out a little while back to check its condition so I should be able to take care of that easily. I really dont understand why they put that stupid post there but I just broke it off with a screw driver. Will look into the egr. Does anyone know what the map sensor reading should be around?
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  #83  
Old 09-15-2013, 11:28 AM
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Quote:
Originally Posted by greenwayer View Post
Old and new plugs
the old plug dosen't even look that bad.
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  #84  
Old 09-18-2013, 08:29 PM
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Re: Horrible, I mean really bad, mpg on my hemi

Today when my mechanic checked all my sensors he found out that I had a vacuum leak and my car running rich and u could smell it all the time and when he fixed that an re programmed my diablo with a new tune since I have a comp cam Im getting over 300 miles on my tank using 93 octane and it is running way better now and Im getting about 10.7 in the city or 11 and on the highway I got 19.5 miles a gallon when cruise control after driving for 6 hours and I have a 05 hemi as well
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