13.30s with super low rail press!

dmaxfireman

'Can do' kind of guy
Apr 8, 2007
2,329
1
38
CT
i wonder if you got any bad fuel and your rail fittings are clogged...

have you tried commanding full pressure with the dvt's in efi? to see if your cp3 can make the pressure?
 

paint94979

Beer Nazi
Sep 18, 2006
11,715
8
38
37
how to use DVT function to test rail pressure:

open Scan Tool
turn truck on
connect to scan tool
look at the tabs it will say Console, OBD II, PIDs, Data, Dashboard, Maps, and DVT you could also just press F12
Now turn on the Activate button
Click on Desired Rail Pressure Control
where it says 40MPA increase that to 180MPA and if your truck goes to 26,000k then your CP3 is not bad.

You could also avoid ALL of this stuff my simply unplugging your Fuel Pressure Regulator connector like i said a week ago
 

RTanner

New member
May 5, 2010
33
0
0
Schaumburg, IL
how to use DVT function to test rail pressure:

open Scan Tool
turn truck on
connect to scan tool
look at the tabs it will say Console, OBD II, PIDs, Data, Dashboard, Maps, and DVT you could also just press F12
Now turn on the Activate button
Click on Desired Rail Pressure Control
where it says 40MPA increase that to 180MPA and if your truck goes to 26,000k then your CP3 is not bad.

You could also avoid ALL of this stuff my simply unplugging your Fuel Pressure Regulator connector like i said a week ago

Yea, i didnt have that step by step procedure! :D Honestly ive been pretty lazy about further diagnosis, eventually ill try the dvt thing but i have kinda lost all motivation right now. :(
 

duratothemax

<--- slippery roads
Aug 28, 2006
7,139
10
0
Wyoming
The problem with just shimming the FPRV is that over time it can get so weak that it will still pop open... I have had the Race Valve in for a few years now with not a single issue. Best 50$ i have spent

x2. I shimmed mine years ago and still had some rail pressure issues. Put in a race valve and I couldnt beleive the difference.
 

CCSBLBZ

New member
Dec 11, 2009
36
0
0
So what shouhld be expected, is it alright to be a few thousand shy,(26,000vs24,000), or should it be alot closer? If the pressure isn't there, will the timing stay the same, and be early? If enough fuel is not there, can the lack of fuel wreck a motor due to over advanced timing?
 
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03-GMC

Let there be light!!
Mar 26, 2009
485
0
0
38
SLC, Utah
how to use DVT function to test rail pressure:

open Scan Tool
turn truck on
connect to scan tool
look at the tabs it will say Console, OBD II, PIDs, Data, Dashboard, Maps, and DVT you could also just press F12
Now turn on the Activate button
Click on Desired Rail Pressure Control
where it says 40MPA increase that to 180MPA and if your truck goes to 26,000k then your CP3 is not bad.

You could also avoid ALL of this stuff my simply unplugging your Fuel Pressure Regulator connector like i said a week ago


This is great info, thanks paint :thumb:

Book marking this so I can check a few things when I get home.
 

Redbowties88

Sideways > Straight ;)
Aug 24, 2009
1,943
1
0
609 New Jersey
how to use DVT function to test rail pressure:

open Scan Tool
turn truck on
connect to scan tool
look at the tabs it will say Console, OBD II, PIDs, Data, Dashboard, Maps, and DVT you could also just press F12
Now turn on the Activate button
Click on Desired Rail Pressure Control
where it says 40MPA increase that to 180MPA and if your truck goes to 26,000k then your CP3 is not bad.

You could also avoid ALL of this stuff my simply unplugging your Fuel Pressure Regulator connector like i said a week ago

nick is that test really accurate? it seems to me like it would be quite easy to build 180mpa with the truck at idle. much harder with a fuel command though:confused:

just thinking outloud
 

03-GMC

Let there be light!!
Mar 26, 2009
485
0
0
38
SLC, Utah
nick is that test really accurate? it seems to me like it would be quite easy to build 180mpa with the truck at idle. much harder with a fuel command though:confused:

just thinking outloud

I know I just talked to a GM tech and he told me the beginning of an injector test starts out with this. They comand 160MPA and if the rail goes below 158MPA then they will continue with the rest of the tests.
 

TrentNell

Finally underway !!!!!
Jul 7, 2008
7,543
0
0
44
slc tuah
nick is that test really accurate? it seems to me like it would be quite easy to build 180mpa with the truck at idle. much harder with a fuel command though:confused:

just thinking outloud

If you have a rail issue it will show most times with that test , when i had bad injectors I could only build 22k at idle with Dual Cp3's :eek: , minor issue's it may not spot but it is def work checking , it only takes 5 min and could tell you alot .
 

dmaxfireman

'Can do' kind of guy
Apr 8, 2007
2,329
1
38
CT
have you replaced your fpr or modded it? it looks cranky.. too high when you command low and too low when you command high.