12 Valve 2nd Gen Dodge Cummins 94-98 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with P7100 Injection Pumps

1998 12 valve 2X4 2500 fuel milage

Old Sep 28, 2010 | 10:55 PM
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Question 1998 12 valve 2X4 2500 fuel milage

Just purchased the 98 with 100K and have completed 100k check up. All oils/filters/liquids changed. Transmission bands adjusted, TPS cleaned. Empty 18-21 (68-72)mpg. 5th Wheel GCW 16.6K mileage down to 11 (68-72)mpg, dropped speed to 55mpg and only got 13.7 mpg. This is a stock vehicle. Besides the right foot weight removed any suggestion for improvement in towing mpg increase??
 
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Old Sep 29, 2010 | 07:41 AM
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cold air intake and exhaust will help
 
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Old Sep 29, 2010 | 04:38 PM
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turn ur starwheel in. that helped me
 
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Old Sep 29, 2010 | 07:18 PM
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I've tried a lot of stuff, but no matter what I do or what I tow, big, small, heavy, light, I get 12 mpg average while towing. Empty I get 19-20 at 60-65 and 17-18 at 75-80. This is when it was stock, when it had ~340 hp and now it's around ~400 and getting still about the same. I look at it as, if it was gas and had the power it has, I would get 10 empty and less than 5 towing like I do.
 
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Old Sep 29, 2010 | 07:22 PM
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I get about 16-18 mpg @ 60-65 mph (auto transmission)...
 
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Old Sep 29, 2010 | 09:35 PM
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i get 28.8 on the last trip i took doin 65-70
 
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Old Sep 29, 2010 | 11:03 PM
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In your dreams....
 
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Old Sep 30, 2010 | 01:20 PM
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Yeah but your tc is bummed. I have hand calculated numbers of a stock '96 getting less than 15 and then changing a few things ($18,000 in work) and getting 34. Granted these are extreme cases and are NOT common nor are they normal. Average on that truck was 26 after this work.

There area ways of doing some major improvements but there isnt a stock truck out there with a fuelling plate and an exhaust that would get this sort of improvement! You have to pay to play.
 
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Old Sep 30, 2010 | 03:49 PM
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Originally Posted by Wyatt Earp
Yeah but your tc is bummed. I have hand calculated numbers of a stock '96 getting less than 15 and then changing a few things ($18,000 in work) and getting 34. Granted these are extreme cases and are NOT common nor are they normal. Average on that truck was 26 after this work.
What was done there? Auto or manual?


Mrs. Evil's Dad claimed his 96 dually 4X4 got 26-28 mpg ???
 

Last edited by Dr. Evil; Sep 30, 2010 at 03:52 PM.
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