Brutal MPG!

[24VTurbo]

Hey guys, I've been averaging 450 km to a tank! :banghead: i dont understand it! my 400 in my old ford 1/2 ton gets better miledge!! can anyone give me some info onto what this might be!?Thanks guys:pray:

[LiveOak]

Can you provide more background on the engine and fuel system of your truck? It would be very helpful in providing a more practical and accurate reply to your question. In the mean time you might try cleaning or replacing the IAT sensor. http://dodgeram.org/tech/dsl/sensors/IAT/clean.htm Mike also has that topic very well covered too! http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/26-engine-systems/59-intake-air-temperature-sensor-iat-sensor

[Mopar1973Man]

Hey guys, I've been averaging 450 km to a tank! :banghead: i dont understand it! my 400 in my old ford 1/2 ton gets better miledge!! can anyone give me some info onto what this might be!? Thanks guys:pray:

More information about the truck is needed for sure. Mods, any kind of work, mileage, etc. 450 km = 279 miles or roughly 9.3 MPG figuring against 30 gallons of fuel. Ouch... So I need to know what is your fuel pressure and if there is any error codes present? (Yes. Error codes can be present without a check engine light)

[24VTurbo]

wow! responses are waaaay quicker and sound like you guys actually wanna help compared to cummins forum! I like that!! this is the new site for me! GREAT job mopar man i just did my sig. i got no CEL on but i can get my codes checked tonight in about 3 hours. and my fuel pressure is 15psi. and 11psi WOT I have yet to install my FASS! thinking i should have got that mech pump I just read about that is belt driven off your crank!

[Rogan]

but, on a 20gal refill, or even a 23 gallon refill with a 25gal tank, 23gal = 12.1. 20gal = is almost 14mpg..But follow Michael's lead.. we need more info.

[24VTurbo]

Can you provide more background on the engine and fuel system of your truck? It would be very helpful in providing a more practical and accurate reply to your question. In the mean time you might try cleaning or replacing the IAT sensor.

http://dodgeram.org/tech/dsl/sensors/IAT/clean.htm

Mike also has that topic very well covered too!

http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/26-engine-systems/59-intake-air-temperature-sensor-iat-sensor

Wow! i never even thought of cleaning that sensor! I know when the motor was rebuilt I just screwed it back in and I remember is was BLLLLAAAACCCKKK! and that was 25,000 km ago!!! im gunna do that before I go to my buddys and scan my truck!! thanks!

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but, on a 20gal refill, or even a 23 gallon refill with a 25gal tank, 23gal = 12.1.

20gal = is almost 14mpg..

But follow Michael's lead.. we need more info.

450km is at quarter tank. its usually $110-$130 fill. the best I ever got was 600 km when the truck was BONE stock and i had a tail wind the whole way.

[Mopar1973Man]

Well Lets say you need a goal to hit. I've been very capable of hold 21-22 MPG for the most part so for you that would be 1,100 Km to 1,200 km roughly speaking.So your getting a new fuel system that a good start. But I rather concerned with the condition of the VP44. I think you might be fighting a losing battle against a pup that might be totally wore out. This why I'm asking about the fuel pressure and the error codes because it might give a clue to what is wrong. Do you see any white smoke at start up? (digging for more info)

[24VTurbo]

The IP say's reman on it. when I got the truck I put a FP gauge on it. it was 14psi idle and 9psi WOT. I replaced it with a brand new Cummins fuel pump. and it brought it up to 15 & 11, and no white smoke ever...

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The codes ive gotten are ( no communication between ECM and IP ) turned out to be plug on back of IP was cracked and was hit and miss making a connection... new wiring harness later... and the over boost code I use to always get until I chiped it now i havent seen it. But like I said ill get them checked tonight..

[Mopar1973Man]

I got the truck I put a FP gauge on it. it was 14psi idle and 9psi WOT.

and it brought it up to 15 & 11

Ekkk... Low pressure. Your lowest pressure you want is 14 PSI. But 10 PSI is the service limit. But remember as the pressure fall below 14 the overflow valve starts closing and is completely closed by 10 PSI so cooling and lubing got limited.

no white smoke ever

We'll see if the previous low pressure has any tell tales with error codes.

[24VTurbo]

codes are: p0237 turbo boose sensor A circut low ( I unplugged my chip while it was running before I went to get codes read. CEL came on and went out as soon as I plugged it in. Im guessing I got this code from doing that?P1689 no communication between ecm and Injection pump, this was the code I kept getting when the main plug on my vp was brocken. I never did clear codes after I fixed it. so that would have been from then. anyways I cleared the codes, filled up and drove 55 mph home. (40 km) usually this would take me 1/8th of a tank. but its still over full... I usually drive 90km/h on my speedo at 1900 rpms. I used my gps this time and turns out i have been going 70mph this whole time. when I go 55mph my motor is only turning 1400 rpms. is this to low? or is that okay. it was hard to keep a constant 55 mph because I barely had any pressure on pedal at all lol. this tank Im gunna drive 55mph and well see what happens. I cleaned the IAT sensor ( plugged solid ) i could tell immeditally the difference in the responisvnice of truck. Im going to cleap map tommorow, set my APPS, and set my valves as well. and see if this helps at all. has anyone screwed around with valve lash? like gone a few thousands tighter???

[CUMMINSDIESELPWR]

i think 8 and 18 is as tight as you want

[diesel4life]

just looking at your sig i dont know how much better your going to get with your set up. 35" tires and 150 horse sticks is not a good recipe for fuel mileage! Even if you baby it you still wont see the numbers of a stock truck. Im stock with the exception of a smarty and when i stepped up to a 285/75 my mpg dropped by about 1. I drive conservative and i avg 20 to 21 mpg per tank empty no towing. Thats a mix of country road and freeway with maybe 10 percent in town driving just to give you something to compare to.Someone else will be able to chime in a little more about your set up but im thinkin a stock HX may be about at its limits with those big injectors which isnt helping your situation either

[Mopar1973Man]

1999 Dodge 2500 ExtCab. SB. 4x4. 4:10 gears. dana 80 rear. rebuilt NV4500. rebuilt 24V Cummins. Fass 200gph. 5" straight pipe into dual 5" stacks. DDP150 sticks. Rebuilt HX35. Edge Comp Box. mech. gauges (fuel,oil,pyro,boost,watertemp) 35x12.50x20 Mud Grapplers. 20" XD badlands. 3" level + 3" body lift. HD front end... oil leaks

Well if it was me in the quest of MPG's...

[*]Ditch the 4.10 gear and swap for 3.55 gears.

[*]Ditch the 35" tires and get back down to 235's

[*]Ditch the 3' body lift and cut your wind drag down.

[*]Ditch the 150HP sticks and drop down to +40 (RV275) to no more than +75HP

You got way to much going against you to gain any kind of MPG's.

Like for example for every 4 pounds of rotational mass you remove your required 1 less HP to keep rolling. So I can bet you got something like 120 pounds of weight in one tire/rim assembly. (attach pic) What you gain from the size for ratio you lost in weight of the tire.

The more aggressive the tread pattern the more rolling resistance you have. Give you an idea the optimal tire for rolling resistance is a racing slick. Since its smooth face it has none.

Then frontal area. that 3" body lift just place your truck even higher into the wind creating more drag.

Oh rule of thumb if you want 20+ MPG you Pyrometer need to be below 600*F and the boost below 5 PSI. In the video below my boost is 1.5 to 3 PSI and pyrometer wondering between 450-600*F. Now that efficient.

Here is a sample.

http-~~-//www.youtube.com/watch?v=SRQdoPs_tLo

[Rogan]

as previously stated, 150hp sticks + hx35 is way too much fuel; the hx35 doesn't truly flow enough air to clean-burn the 150's fuel delivery.I'd love to know what the 35"s on a 20" wheel would weigh. I can imagine quite a lot. I would not be surprised if there's 5-600 lbs in un-sprung rotating mass there.Even with 35s, if you're turning 1400rpm at 55mph with 4.10:1 R&P, that doesn't sound right. Unless that's GPS-speed, and your speedo showed like 30mph..

[24VTurbo]

Well sounds like its time to swap in a 1st gen ve cummins. I really don't want to get into changing my gears and ditching my $3400 tires and wheels. I just thought something was wrong with truck cause when I bought it it was bone stock and I've always gotten shitty miledge...

[rancherman]

our 2000 Ram 3500 dually 4X4 USED to get 18-20 mpg (according to the display) on pure flat roads, no wind, and 55-60. (empty) I don't know if that is close to actual or not, but it's sure less than it used to be.Last week when I pulled that '98 home on the flatbed, 8-9 was all I could manage... and had a 45mph tailwind to boot. Even without a trailer, it's difficult to find 16+mpg lately.3.55 gear, stock tires, running 5th gear @ 55mph, I'll get 8-9mpg.. and 6th gear @60-65mph will knock off 10-11 mpg No white smoke @startup....just a light puff of black. Heading out the door right now to implement a IAT cleansing! I have wondered though, if it's puking that much fuel.... why is the exaust so clean?? I would think at 8 mpg.... there would be quite the smoke trail! even when 'totally in' the throttle.I'll have a report on the IAT here later tonight.. stay tuned

[dripley]

Are you using the GPS for miles driven or the odometer? Any time you go bigger on the tires its going to throw the odometer off.

[diesel4life]

Had to make an unexpected trip to cincinnati today. A little over 300 miles one way i filled up when i got to town and hand calculated my mileage as i was thinking about what you were saying you got for mileage. It came out to 15.8 mpg i ran between 65 and 70 the entire trip. Could have gotten a little better but it was pouring rain the whole way and was fighting a nasty crosswind from Sandy. My trailer weighs in at 2400 and my best guess on the car is 3000 to 3500?just a guess i dont know for sure so that puts me around 6k. Not alot of weight by any means but just tryin to give you an idea of what a stock truck (besides a smarty) will get. Another factor is how you drive. Im pretty conservative on the skinny pedal i dont use cruise and i dont keep my foot into it just to keep up with traffic. I run the speed limit and if people wanna go around me then theyre more than welcome. You were saying you got bad numbers even when stock what kind of mileage were you getting?

[24VTurbo]

Are you using the GPS for miles driven or the odometer? Any time you go bigger on the tires its going to throw the odometer off.

Ive been using the odometer... it would be out you figure?

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[ATTACH=CONFIG]4600[/ATTACH]

Had to make an unexpected trip to cincinnati today. A little over 300 miles one way i filled up when i got to town and hand calculated my mileage as i was thinking about what you were saying you got for mileage. It came out to 15.8 mpg i ran between 65 and 70 the entire trip. Could have gotten a little better but it was pouring rain the whole way and was fighting a nasty crosswind from Sandy. My trailer weighs in at 2400 and my best guess on the car is 3000 to 3500?just a guess i dont know for sure so that puts me around 6k. Not alot of weight by any means but just tryin to give you an idea of what a stock truck (besides a smarty) will get. Another factor is how you drive. Im pretty conservative on the skinny pedal i dont use cruise and i dont keep my foot into it just to keep up with traffic. I run the speed limit and if people wanna go around me then theyre more than welcome. You were saying you got bad numbers even when stock what kind of mileage were you getting?

best I got was 600km or 650km I cant remember that was bone stock.

now I filled up last night and I got 92 km and its still over full! is this good???? . I never once got into the throttle, kept my smoke down to none at all basically, and drove a steady 55mph. about 8 km of that is not highway. If i go fill up right now how would I calculate my miledge? i have my receipt from last night:

(this was almost on the fuel light)

litres: 95.38

price: $1.17/L

total: $112.45

so how many litres would my tank hold? im confuseed on how to figure out my miledge. im gunna go top up my tank and see what I get!

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this is my truck p.s

[dobienut]

thinking i should have got that mech pump I just read about that is belt driven off your crank!

Had one for must be 4 years now...no regrets. 16-19psi always with a little splash of 2 stroke mix