LBZ: Thinking about some new go fast parts. What is considered good Rail Pressure?

Dozerboy

Dozerboy

Well-known member
Jun 23, 2009
4,837
413
83
TX of course
Thinking about a new turbo, but dont want to be pissing my $$ away. My truck has never had very good RP it only holds 23Kpsi at 2700us and 22.5K at 2800us, and has thrown low RP codes on both tunes a handful of times. I don't mind throwing a CP3 on to while doing the turbo that was kind of the plan, but I would hate to find out I need injectors too. $4.5k for 60s ouch....

I checked my balance rate today and they aint great. With the truck warm 2 of them are 3.5 with the AC on in Neutral and down to 2.8 in gear with the AC on. I recall reading I should check the return rates too. Something about just pulling the return line lose and measuring the fuel out of it with the truck running. My truck has 173K on it and stock other then EFI and lift pump.

Whats yalls thoughts? Any info at checking the injector return rates would be great. Thanks
 
TeaBagger2006

TeaBagger2006

Im a Garrett Nut Swinger
May 11, 2008
3,123
15
38
Bis ND
id say do a danville stage 2 68mm. its a straight drop in and has too many positive reviews. i would do the turbo first then see how you like it. lbz have peak 26k rail pressure so you are a tad under. a fresh cp3 wont hurt the wallet too much.if it was me id stick with the stockers and build the trans to handle the new turbo and tuning..... bigger injectors are a pretty penny
 
Dozerboy

Dozerboy

Well-known member
Jun 23, 2009
4,837
413
83
TX of course
Thanks Burn Down

Im looking at the 3794 Stg2 just not sure that Im going to do the 68. Not sure that I see much of a befit. Sticking with a stock appearing turbo is in the back of my mind. If the 3794 is even considered that. The Trans is done.

What has me concerned is that currently my truck makes more power 2700us then any more. My guess is due to the dropping rail. Im sure the 3794 will make more power with a 2700us, but how much?

Im killing the pilot at 3K RPMs. Ive always though my CP3 was weak. Ive never built a tune that would run more them 2800us @ 150MPa.

Ne-max you lost me can you log the position of the FPR with the V2?
 
ikeG

ikeG

Oughta Know Better
Apr 19, 2011
2,431
128
63
Western PA
www.facebook.com
Gaining that rail pressure back, whatever the reason for it being low, will result in a big power increase. Like you are aware of, its possible the injectors may need refreshed. At that mileage it wouldnt be uncommon that they should be replaced. If it were me i'd pull the injectors to get them tested, and once the results are in purchase a sportsman pump if funds allow. Your turbo will more than likely outlast the fuel system so i'd start there.
 
Ne-max

Ne-max

I like turtles
Nov 15, 2011
3,361
64
48
Lincoln, Ne
Dozerboy said:
Thanks Burn Down

Im looking at the 3794 Stg2 just not sure that Im going to do the 68. Not sure that I see much of a befit. Sticking with a stock appearing turbo is in the back of my mind. If the 3794 is even considered that. The Trans is done.

What has me concerned is that currently my truck makes more power 2700us then any more. My guess is due to the dropping rail. Im sure the 3794 will make more power with a 2700us, but how much?

Im killing the pilot at 3K RPMs. Ive always though my CP3 was weak. Ive never built a tune that would run more them 2800us @ 150MPa.

Ne-max you lost me can you log the position of the FPR with the V2?
Click to expand...

Yes you can. I learned that actual raol, commanded rail and fpr position will give you a lot of info.
 
Dozerboy

Dozerboy

Well-known member
Jun 23, 2009
4,837
413
83
TX of course
NC-smokinlmm said:
FPRV blocked or shimmed?
Click to expand...

Never had to do either. Done the bottle test years ago and not a drop of fuel.

04jimc said:
If it were me i'd pull the injectors to get them tested, and once the results are in purchase a sportsman pump if funds allow. Your turbo will more than likely outlast the fuel system so i'd start there.
Click to expand...

Going to see what I can find out on my own. Not sure there are any shops around here that would do it right.

Ne-max said:
Yes you can. I learned that actual raol, commanded rail and fpr position will give you a lot of info.
Click to expand...

Thanks I do actual and commanded, but will add FPR position.


Might be time for me to get a good repair manual recommendations?
 
melms23

melms23

Member
Jul 30, 2011
253
0
16
WI
FWIW I had to put a rail plug in my lmm. Wouldn't hold rail pressure even after being shimmed.
 
N

N2BRK

Well-known member
Dec 31, 2009
1,946
269
83
depending on your tune, that doesn't sound crazy low. I just tweaked my buddy's truck after we saw numbers like yours on his log from the track. He's on a stock LMM cp3 at around 90,000mi. I adjusted B1015 to ask more from the regulator and RP went to 25k+ instead of low 23 with a dip to 22 prior.

YMMV and use caution, but I'd log that puppy and then log a change to B1015 if it was my truck. You might find that you're fine.

Wally
 
NC-smokinlmm

NC-smokinlmm

<<<Future tuna killer
May 29, 2011
5,077
275
83
At Da Beach
Dozerboy said:
Never had to do either. Done the bottle test years ago and not a drop of fuel.



Going to see what I can find out on my own. Not sure there are any shops around here that would do it right.



Thanks I do actual and commanded, but will add FPR position.


Might be time for me to get a good repair manual recommendations?
Click to expand...

I'd plug it just for peace of mind.
 
Dozerboy

Dozerboy

Well-known member
Jun 23, 2009
4,837
413
83
TX of course
N2BRK said:
depending on your tune, that doesn't sound crazy low. I just tweaked my buddy's truck after we saw numbers like yours on his log from the track. He's on a stock LMM cp3 at around 90,000mi. I adjusted B1015 to ask more from the regulator and RP went to 25k+ instead of low 23 with a dip to 22 prior.

YMMV and use caution, but I'd log that puppy and then log a change to B1015 if it was my truck. You might find that you're fine.

Wally
Click to expand...

Thanks Wally
I must have missed the discussion about B1015 in the past. I'll be a little pissed if that brings my rail up. For years I just though my CP3 was an underachiever. Oh well thats what happens when you do your own tuning. From what little I have read this might fix my issue.

Now I just need to get my truck back out of the body shop. I want to start shorting my rods yet this year!:woott::woott:As long as I don't end up with a window in my block..:eek:
 
Dozerboy

Dozerboy

Well-known member
Jun 23, 2009
4,837
413
83
TX of course
Tested each bank of injector to see how much fuel they where returning. Both where fine.

Well B1015 was worth 300PSI. After that I ported my DS fuel rail and that was worth 1000PSI Im currently hold over 23Kpsi on a 3100us tune. I know I can gain some more if I lower my shift point from 3500 to 3300, but who knows if that will make my truck any faster or not.

The PSI that I have posted that Im holding is a average over a 0-90 WOT run.

Go fast parts are on hold for now we decided to do some more infertility treatments...:( but my boy needs a little sister to pick on.:roflmao: I also want to see if I really want to do a 12mm stroker or not based on how much RP i can get my stocker to hold. My engine will really be hating life if I do the 12mm.
 
You must log in or register to reply here.
Top Bottom