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Discussion Starter · #1 ·
Hi all recently I have had some problems with my 2013 Ram 2500 with the 5.7l Hemi. Traveling through the mountains(RPMs fluctuate with hills and acceleration) I averag around 23L/100km. But when i drive on flat prairie highways doing a 100km/h on cruise i will get around 30L/100km (consistent rpm around 1500 going in 6th gear). If i engage tow haul (draws out shifting point, more pressure in the transmission) i can average 18L/100km on a flat highway doing 100km/h at 2100 RPM. Or if i drop the truck into fourth gear doing 100km/h it will average around 21L/100km at 2500 RPM. (at low rpm it burns lots of fuel. at higher RPM it does better on fuel) Around town it does allright on fuel. I have spent 5k$ at the dealership getting the lifters done that did nothing. I have changed the spark plugs and O2 sensors are good. If anyone has an idea of why the truck burns so much fuel at a lower RPM cruising down the highway, it would be much appreciated.
 

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Hello and Welcome to the HEMI Truck Club Forum. Enjoy your Ride and the Site.
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Sadly it’s because it’s a heavy truck and a small motor. It’s lugging to maintain speed even though it seems as though it’s not.
 

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Discussion Starter · #6 ·
Sadly it’s because it’s a heavy truck and a small motor. It’s lugging to maintain speed even though it seems as though it’s not.
Sadly it’s because it’s a heavy truck and a small motor. It’s lugging to maintain speed even though it seems as though it’s not.
ok thanks but in tow haul or higher RPM the fuel efficiency bar/gauge is steady. at low RPM the bar is always moving and trying to find the correct amount of fuel to put into the system. currently im trying to find why the fueling would not be consistent and eliminate that problem. Any ideas what would cause my feul consumption to wander at low RPM?

49846
 

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It’s all a calculation of weight and throttle needed to keep engine at a set rpm. It’s simply the truck is heavy and the computer is varying the throttle or wind resistance is playing its part.
 

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Discussion Starter · #8 ·
It’s all a calculation of weight and throttle needed to keep engine at a set rpm. It’s simply the truck is heavy and the computer is varying the throttle or wind resistance is playing its part.
How then does tow haul give me better fuel consumption? what do you recommend i do to stop the computer from wandering ?
 

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In tow haul it normally stays out of lockup or 5/6th gear which will raise the rpm and make more torque thus allowing the engine to hold a steady throttle to maintain same speed. Not much you can do PCM does it all for you based on inputs it sees is all
 

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I stay in tow/haul mode until I reach 55 if posted as such. Other wise Tow/Haul is active under 55 for side roads or twisty roads. ;)
 

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Discussion Starter · #11 ·
I have come upon some new information and would like your opinions. What if my torque converter clutch is slipping then grabbing, then the truck would continually be putting more fuel in to make up for the powerand that would explain the wandering fuel consumption at lower RPM. Would that make sense?. Trying to hold the truck at a steady 100km/h with my foot is a struggle because the trucks torque converter clutch is continually slipping, thats the theory, not sure if it is actually slipping.( hope i am understanding the torque converter)
 

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Will need a scanner to confirm this. The data will show you engine and input speeds and give you a slip percentage and how locked up converter is. Only odd part is if it was skipping the computer would set a code for it with only a 150rpm slip difference over 2-5secs
 
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