Fuel Milelage

[jimnance]

Originally posted by Parshal

I averaged around 17. 5 in town before I added the EZ. I was getting 18. 7 in town with the EZ. Last check at fillup before towing was 16. 78 though so I'm a bit worried something thas happened here. Before the EZ, I got 12. 5 towing my 3600 lbs. travel trailer at 70 mph. I just towed the trailer this weekend with the EZ and I got around 11 mpg at 70. Best was 13 and worst was 8. 5 mpg. I did add 1 1/2" blocks to the trailer to get it to level properly, though. I can't figure out how people are towing 10,000 lbs. trailers and getting over 13 mpg. It blows my mind when I look at the little thing I'm towing.

Since the present version of the Edge only increases rail pressure it should not be a surprise that fuel economy has decreased. Raising rail pressure does not improve efficiency. It does improve power because more fuel is being delivered to the engine.



Don't expect improved fuel economy until boxes which control fuel pressure AND injection timing. Even then, you'll have to resist the temptation to hammer the pedal!

 

[Parshal]

Originally posted by jimnance

Since the present version of the Edge only increases rail pressure it should not be a surprise that fuel economy has decreased. Raising rail pressure does not improve efficiency. It does improve power because more fuel is being delivered to the engine.



Don't expect improved fuel economy until boxes which control fuel pressure AND injection timing. Even then, you'll have to resist the temptation to hammer the pedal!

But this is wrong. I have seen a 1. 2 mpg improvement in mileage since adding the EZ and that is over 3,000 miles. Most people with the EZ on the '03's are seeing the same results.



I forgot to add that towing the load I was at about 15 - 16 lbs. of boost and 725 degrees pre turbo on flat and level.

 

[jimnance]

Let me say that it shouldn't improve. Your driving habits may vary.



What the Edge does which is good is to increase the amount of air delivered along with the fuel delivery. I don't see where efficiency would improve however.



I for one will wait for the next generation of Edge which promises more efficient fuel delivery. However, they say this version will not be released for another four months.

 

[Maddey]

Got the truck back last night. Dealer did not find any codes when they hooked up the computer. They said that they reflashed the computer to reset everything and to see if that helps. It is really dissapointing to hear things like that, knowing that I was getting 17mpg out of my perfectly good '01 2500 4x4 and 19mpg out of my '99 3500 4x2. I called Cummins to see if they had any input, however, they told me that they cannot work on the '03 since they are providing the new engines to Dodge with no warranty. They did however, agree that I should be getting much better mileage and there is definitely something not right. I guess I will just hope for better mileage as time goes on.

 

[Mathew Clausen]

Jim - on rail pressure -vs- economy - think about what raising the rail pressure does ..... if your cruising down the road you need 'x' amount of power. To get that power you need to inject a certain amount of fuel. At a certain pressure (stock) - you need some duration to do that. If you raise the pressure - the duration (or injection time) is shorter to get the same fuel. So even if you don't change the start of injection - you have shortened the duration. -AND - the ECM thinks you are not putting out as much power as you are (because you are tricking it) - so I suspect in many situations the start injection timing is changed from stock because the ecm thinks your load is less than it really is.



I could be off here as I certainly don't know all the details - but it makes sense to me that increasing the injection pressure will change the timing. Apparently (from the mileage that people are seeing) it changes it in a direction that is good.



But - I think I will wait till the boxes that actually just change the injection timing directly come out because that seems like a better (although more complicated) approach.



Mathew