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02cumminsdude

Two in one: MPG and cool weather update

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Some of you may remember my "slightly disappointed with MPG" thread. My first fill-up since then I got 16.8 mpg, up from 14.2, just changing my driving style and installing a AFE stage 2 about halfway through the tank. Better, but not good enough yet. Still have to pinpoint the leak behind the head, not sure if it's at this banjo bolt which I have yet to find with my mirror lol, or the return line T fitting. So I'm expecting gains yet and still adjusting my driving, but good results so far.Anyways, I'm having a slight issue in low-mid 70 degree weather. Not only does it take noticeable longer to warm up, but it also flattens out at 1400 rpms or so through all the gears until it warms up substantially. This may just be normal for these trucks, but I've had it since last spring and it doesn't do it in summer 80+ degree weather. The Juice limiter is turned off, so it isn't that. It didn't do it quite as bad in the spring in similar weather, maybe it's the cooler air from the AFE being pulled in? I'm just worried that if it is doing now, how much worse will it be in the 20's and 30's?

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Some of you may remember my "slightly disappointed with MPG" thread. My first fill-up since then I got 16.8 mpg, up from 14.2, just changing my driving style and installing a AFE stage 2 about halfway through the tank. Better, but not good enough yet. Still have to pinpoint the leak behind the head, not sure if it's at this banjo bolt which I have yet to find with my mirror lol, or the return line T fitting. So I'm expecting gains yet and still adjusting my driving, but good results so far. Anyways, I'm having a slight issue in low-mid 70 degree weather. Not only does it take noticeable longer to warm up, but it also flattens out at 1400 rpms or so through all the gears until it warms up substantially. This may just be normal for these trucks, but I've had it since last spring and it doesn't do it in summer 80+ degree weather. The Juice limiter is turned off, so it isn't that. It didn't do it quite as bad in the spring in similar weather, maybe it's the cooler air from the AFE being pulled in? I'm just worried that if it is doing now, how much worse will it be in the 20's and 30's?

If you follow the return line off of the VP towards the back of the engine it will lead you to the tee. It can be seen by looking over the fuel cansiter just past the IAT sensor. If you just reach around the back of the head you can feel the return line banjo bolt in the center about 3" down. Not sure how to help with your second problem.

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Some of you may remember my "slightly disappointed with MPG" thread. My first fill-up since then I got 16.8 mpg, up from 14.2, just changing my driving style and installing a AFE stage 2 about halfway through the tank. Better, but not good enough yet. Still have to pinpoint the leak behind the head, not sure if it's at this banjo bolt which I have yet to find with my mirror lol, or the return line T fitting. So I'm expecting gains yet and still adjusting my driving, but good results so far. Anyways, I'm having a slight issue in low-mid 70 degree weather. Not only does it take noticeable longer to warm up, but it also flattens out at 1400 rpms or so through all the gears until it warms up substantially. This may just be normal for these trucks, but I've had it since last spring and it doesn't do it in summer 80+ degree weather. The Juice limiter is turned off, so it isn't that. It didn't do it quite as bad in the spring in similar weather, maybe it's the cooler air from the AFE being pulled in? I'm just worried that if it is doing now, how much worse will it be in the 20's and 30's?

Is it possible that a PO lived in a very cold climate? It's sounds like it's PCM driven to keep from damaging an engine with cold cold oil to me. I don't think I would worry about it, unless it worsens. It could be one of the add ons not sealing something correctly, until there is some warmth present. Call Dodge and see if the had an extreme weather flash, that would cause your engine to act that way.

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Fuel pressure is always a solid 14-15psi. I haven't done any WOT runs since I've been driving more conservative to increase mileage. It runs flawlessly when warmed up, I've just noticed that with only a 10 degree difference in weather in the 70's it's such a noticeable surge that it worries me about even cooler temps coming up. Would I just call Dodge and give them the VIN and they can look it up to see if it's been reflashed?

Dripley, I've seen the T fitting back there, just haven't been able see or feel the banjo bolt yet, which is probably where it's leaking since it's harder to get there :banghead:

- - - Updated - - -

Punched it in 5th for a few seconds on the way home, PSI dropped to 12 and held strong. Wasn't quite operating temp when I did this, but warm enough for the surging to stop. I'm not sure exactly what the surging feels like from an apps issue, but from what I've read here, it almost feels like that, but that wouldn't go away after warming up would it?

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I think it possibly could come and go with operating temps. When mine went out, it tried to give me a warning a few times before it went for good and it was always when i first fired it up after it had been sitting. i would take off, and it would falter or stumble briefly and the check engine light would come on. Once it warmed up, it wouldnt do it any more. This happened 3 times before it went south for good. Are you getting any codes when this happens? Maybe it could be a battery situation? Low voltage when you first start it ad it takes a little while to recharge your batt and then everythings fine? Low voltage makes these trucks do strange things ive seen that first hand too

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Interesting idea. I have no codes, but I do occasionally get the CCD light up in the overhead, it comes and goes and these batteries could be YEARS old for all I know. They also accumulate some build up on the terminals within days of cleaning them. I am planning on fresh batts and cleaning and sealing the leads on the terminals for the winter. Hopefully that clears up the CCD light and takes care of the surge as well. I love an easy fix :thumb1:

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