Fuel rail pressure

M

mechman3

no such thing as too fast
Jan 7, 2015
181
2
18
Saratoga Springs, Utah
Ok so I am relatively new to diesel performance. My truck is as listed in my sig. I was curious as the fuel rail pressure. My cts only reads anywhere from 10K to 16K is the most I have seen. I see guys on the forum stating 20k + for their frp. What are the advantages to a higher frp and what needs to be modified/replaced to get there? Is it worth it on my truck or do I need more mods before I would see any real advantages/gains?

Just a stupid question from someone who wants to learn.:eek:
 
PureHybrid

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
3,495
476
83
Central OH
Have you run it at WOT? A stock truck carries 20kpsi +, nothing needs to be modified. Maybe check/change the fuel filter. And do you have a lift pump?
 
SSchmi5519

SSchmi5519

LLY Cult Leader
Oct 19, 2008
3,387
1
36
Arizona
Your CTS can log actual rail pressure (ACT RAIL) and desired rail pressure (DES RAIL). You should be watching both. That will tell you if there's an issue. You want ACT RAIL to follow DES RAIL as closely as possible.
 
clrussell

clrussell

pro-procrastinator
Sep 23, 2013
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SSchmi5519 said:
Your CTS can log actual rail pressure (ACT RAIL) and desired rail pressure (DES RAIL). You should be watching both. That will tell you if there's an issue. You want ACT RAIL to follow DES RAIL as closely as possible.
Click to expand...


It will actually log it? Or just show both on the screen? I've not played with my cts much.. Be cool if it'll actually log


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SSchmi5519

SSchmi5519

LLY Cult Leader
Oct 19, 2008
3,387
1
36
Arizona
You can still get a pretty good idea if your actual rail is following along with desired just by watching the two values on the screen side by side. :thumb:
 
M

mechman3

no such thing as too fast
Jan 7, 2015
181
2
18
Saratoga Springs, Utah
Ok so I did and actual vs desired were within 0.1 of each other. Max I could get on my mileage tune at WOT was 19.6Kpsi. Max on my boosted drive tune was 23.2Kpsi

I am guessing that my CP3 is doing ok.:thumb:
 
Awenta

Awenta

Active member
Sep 28, 2014
4,090
2
38
CT
clrussell said:
It will actually log it? Or just show both on the screen? I've not played with my cts much.. Be cool if it'll actually log


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Click to expand...
It will log too. It's not great but it works

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Awenta

Awenta

Active member
Sep 28, 2014
4,090
2
38
CT
But I don't remember exactly which parameters it will log

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Henry95

Henry95

Member
Apr 4, 2015
283
0
16
What is the max fuel rail pressure a stock lly cp3 make on a stock tune?

Just curious, mine will make 23.6 and it has 318 thousand km on it.


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N

NRA223

New member
May 20, 2015
288
0
0
I have my CS set up to keep 6 parameters on the main screen. I put desired and actual rail pressure next to each other so it's easy to keep an eye on.
 
Burn Down

Burn Down

Hotrodder
Sep 14, 2008
7,092
28
48
Boise Idaho
You can unplug the regulator on the cp3 and the pump will go to max pressure, ck on the cts what you have. As others stated you should get 23K sitting at idle with the reg un plugged. You can also do it with efi live in the scan tool or use a tech 2.

If it won't make 23k at idle you have fuel issues.

Underload not making rail could be as simple as needing a lift pump depending on how aggressive the tuning is. Or the rail relief valve is leaking, Bottle test will confirm.
 
CaptPhil

CaptPhil

Active member
Sep 10, 2011
1,012
0
36
Delaware
Burn Down said:
You can unplug the regulator on the cp3 and the pump will go to max pressure, ck on the cts what you have. As others stated you should get 23K sitting at idle with the reg un plugged. You can also do it with efi live in the scan tool or use a tech 2.

If it won't make 23k at idle you have fuel issues.

Underload not making rail could be as simple as needing a lift pump depending on how aggressive the tuning is. Or the rail relief valve is leaking, Bottle test will confirm.
Click to expand...
You will actually get 26k with the reg unplugged. The pressure is higher than that, but that is all the lly rail pressure sensor will read.

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Burn Down

Burn Down

Hotrodder
Sep 14, 2008
7,092
28
48
Boise Idaho
CaptPhil said:
You will actually get 26k with the reg unplugged. The pressure is higher than that, but that is all the lly rail pressure sensor will read.

Sent from my SM-G900V using Tapatalk
Click to expand...

Yep your right. But it will still show if the fuel system is healthy or not.
 
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