Rail Pressure at 70+mph with EZ

[JasonCzerak]

What are your rail pressures when cruising at 70 to 75mph?



EZ on 3 on slight hilly highways I see 22,500 and on some inclines 27,000. I put the EZ on 1 it drops 5,000psi, but still at times she gets back up to 25,000.



On top of that you can hear the injectors rattle like crazy. When you roll into the throttle the rattle goes, pressure stays up, little lower but you start to move. I'm assuming more duration is added and the fuel has a place to go.

 

[scootergmc]

What gauge are you using?

 

[ENafziger]

Hey Jason!



I just got my DiPricol rail pressure gauge installed (and some other ones too), and have been watching the effect that the Edge EZ has. I made a thousand mile trip over Thanksgiving, and running at 75 mph, EZ on 1, rail pressure max was about 22,000. With the EZ on 3, it will sometimes get as high as 25-26,000.



I've not noticed any injector rattle with mine. I'm running Smarty #3 (the one with timing), TST on 1/1, and EZ on 1. I downloaded Smarty #9 briefly, and turned TST to 7/7 and did get some rattle (and a burnt clutch). Each truck seems to respond a little differently...



Even driving with cruise control at 75, Smarty #3, TST 1/1, EZ 1, I still only got 17. 4 mpg though... a little disappointing. What are you seeing for mileage?



--Eric

 

[JStieger]

Jason-



With the MP8 off or on I see ~12,000 psi at steady 75 mph cruise. I thought that this was low because of my injectors so I emailed a buddy of mine with stock injectors and same year truck and he sees the same.



With the cruise control on I may see as high as 17,000 psi on a normal 8% interstate hill.



So under normal driving conditions the truck is putting out what the ECM is programmed to do based on boost etc.



However, if I get on the peddle just a bit with the MP8 on, then the rail pressure is accordingly higher.



I know the 04. 5+ trucks have higher idle and cruise rail pressure stock as compared to the 305/555 trucks.

 

[JasonCzerak]

I think I'll unplug the EZ and see what happens



What do you guys get at 40mph, in 4th at 2100rpm, flat ground. I'm a bit over 20,000 with the ez on 3.



I got the DiPrico one.

 

[JMerola]

Jason - this is a great thread. I have been very intersted recently as to what others are noticing in terms of rail pressure with various combos of fueling and driving style.



I am in the process of reworking my truck. I'm hoping to use rail pressure to optimize my fuel delivery. Right now, I am putting about 1000 miles/wk on the truck commuting back and forth to a new job (almost all interstate driving).



With the Smarty on SW 1 (w/DDP injectors), cruising at 68 mph - I am seeing rail pressures of 15-17 K. On grade, the RP will climb to 18-19k, but never over 20k. When I really get into it (passing cars), rail pressure falls to 13-14k, then recovers when I let off.



MPG hand calculated over the last three weeks is averaging 20. 4 mpg.



There also seems to be some variability in my RP at idle and at cruising speed from day to day. Some days, idle rail pressure is 7. 5k, some days 5k. Some days cruising RP is 15k, some days 17k - and I'm not sure why (inherent gauge error, or rail relief valve issues, or FCA/CP3 variablility)? My SOTP meter says the truck feels stronger when the RP measures higher (from one day to the next). Anyone else noticing this?



Anyway, keep the observations coming - they are definitely useful to me and others I'm sure.



The one thing I can say for certain - with any type of duration mod, it sure is a lot easier than I previously though to run the rail dry (with a stock CP3/stock rail that is).



Thanks again for the info,



- Jason

 

[JasonCzerak]

At highway speeds, and ez on 3 and running 25,000+ PSI most of the time. Is this bad? I can put hte EZ down to 1 and it's just about 20,000PSI. I heard pressure bad and pressure good. Well, what about close to max pressure all the time?

 

[JDerbedrossian]

Jason-



With the MP8 off or on I see ~12,000 psi at steady 75 mph cruise. I thought that this was low because of my injectors so I emailed a buddy of mine with stock injectors and same year truck and he sees the same.



With the cruise control on I may see as high as 17,000 psi on a normal 8% interstate hill.



.

Thats good to hear, my gauge shows the same.



Jake

 

[Bob4x4]

Remember the pre 325 motors run lower pressures... ...



Bob

 

[JEstes]

I'm completely new here, so please excuse the dumb question. How high is too high?

 

[CATCRACKER]

after reading this thread i think the ez is coming off the truck. that things makes my injectors rattle so bad even empty now i know why

 

[ENafziger]

I'm completely new here, so please excuse the dumb question. How high is too high?

I remember reading on here that bosch tests our fuel systems at 29,000 all day long (meaning durability testing). May want to check up on that. Also, a steady-state durability test may be very different than some of the quick spiking that occurs when backing off the throttle too quickly with daily driving. I think the general concensus is that pressure is alright if used very minimally (on the lowest setting), and using higher pressure only for track use.

Hope this helps... Eric