Rail Pressure Problems

frontside0815

Corporal
Nov 9, 2016
126
48
0
Germany
Hey there,

since i really have no idea what to look for next, i will try to get some ideas here:

My car has Upgraded Stage 2 Turbos (TTE550) since beginning of 2017. When they were installed, i was having rail pressure Problems at around 25psi redline, but along with LPFP dipping.
So i swapped my Walbro 450 (stage 2 Pump) against an OEM and Walbro 250 inline (Stage 1). Since then my LPFP is rock solid...

But here and there my rail pressure kept dipping- you couldnt really see a real Connection between stable and unstable rail pressure. So we tried mapping around it....

But since two weeks the Problem got worse: 20PSI Redline wasnt making Problems and rail was fine in the last months, but now everything in the near of 20PSI Redline makes the Rail pressure nose diving.

On the Weekend i tried a few things: I changed out my drilled fuel rail for a oem one, which made things even worse and resulted in Dipping rail pressure even at 15PSI Redline, see this log: https://datazap.me/u/raffi/track-v9-und-v6-mit-alter-hdp?log=2&data=3-25-26

Then i installed a new HPFP, which made it a Little bit better, so i could run the 15PSI Map without Problems: https://datazap.me/u/raffi/track-v5-mit-neuer-hdp-0?log=0&data=3-25-26

But when i tried a map with more power and around 20PSI Redline rail keeps crashing (see gear 4):
https://datazap.me/u/frontside0815/track-v2-mit-neuer-hdp?log=0&data=3-25-26

I tried everything:
i have new Index 12 Injectors, like told above a like new fuel pump, i changed out the fpr assembly with the fuel filter inside, i pulled the small filter in the HPFP, i checked all Connections, installed a brand new HPFP (altough the old one wasnt older than 5.000 miles).


I really have no idea what to Change next or how to analyze the Problem... I am not the only one with These Turbos and usually a fuel Setup like mine can handle 25PSI Redline with no signs of Rail Pressure dipping.
 

doublespaces

General of the Army
Oct 18, 2016
8,941
4,145
0
AZ
Ride
2009 E93 335i
Sounds awfully familiar to my situation. I've actually started getting some codes(29F2, 2AAE, 2FCA 2FDA) and my will even go into limp mode shortly after leaving the driveway, but gets better over time. Doesn't make any sense to me.
 

NoQuarter

Major
Nov 24, 2017
1,546
964
0
Indiana, USA
Ride
Z4 35is, 535xi, X5 35i
You are certain of the abilities in your tuning (or whomever is tuning for you) ?

So far, your assessment is essentially:
"The tune must be good" and
"Something must be wrong in the hardware"

Maybe rethink the tuning side of things?
 
  • Like
Reactions: Euro venom

matreyia

Major
Apr 19, 2017
1,748
685
0
Ride
335i e93
Hey there,

since i really have no idea what to look for next, i will try to get some ideas here:

My car has Upgraded Stage 2 Turbos (TTE550) since beginning of 2017. When they were installed, i was having rail pressure Problems at around 25psi redline, but along with LPFP dipping.
So i swapped my Walbro 450 (stage 2 Pump) against an OEM and Walbro 250 inline (Stage 1). Since then my LPFP is rock solid...

But here and there my rail pressure kept dipping- you couldnt really see a real Connection between stable and unstable rail pressure. So we tried mapping around it....

But since two weeks the Problem got worse: 20PSI Redline wasnt making Problems and rail was fine in the last months, but now everything in the near of 20PSI Redline makes the Rail pressure nose diving.

On the Weekend i tried a few things: I changed out my drilled fuel rail for a oem one, which made things even worse and resulted in Dipping rail pressure even at 15PSI Redline, see this log: https://datazap.me/u/raffi/track-v9-und-v6-mit-alter-hdp?log=2&data=3-25-26

Then i installed a new HPFP, which made it a Little bit better, so i could run the 15PSI Map without Problems: https://datazap.me/u/raffi/track-v5-mit-neuer-hdp-0?log=0&data=3-25-26

But when i tried a map with more power and around 20PSI Redline rail keeps crashing (see gear 4):
https://datazap.me/u/frontside0815/track-v2-mit-neuer-hdp?log=0&data=3-25-26

I tried everything:
i have new Index 12 Injectors, like told above a like new fuel pump, i changed out the fpr assembly with the fuel filter inside, i pulled the small filter in the HPFP, i checked all Connections, installed a brand new HPFP (altough the old one wasnt older than 5.000 miles).


I really have no idea what to Change next or how to analyze the Problem... I am not the only one with These Turbos and usually a fuel Setup like mine can handle 25PSI Redline with no signs of Rail Pressure dipping.


Did you follow best practice and replace lpfp sensor AND hpfp sensor when you changed the pumps? Pump replacement is almost pointless if you don't change the sensors. They are tied together. Do it even if you don't think there's anything wrong with them.
 

langsbr

Captain
Apr 5, 2017
1,176
673
0
Ride
07 335i 6MT e90
What fuel? E40ish? What stage 2 pump do you have? Bucketless?
 

frontside0815

Corporal
Nov 9, 2016
126
48
0
Germany
You are certain of the abilities in your tuning (or whomever is tuning for you) ?

So far, your assessment is essentially:
"The tune must be good" and
"Something must be wrong in the hardware"

Maybe rethink the tuning side of things?

I dont tune it myself. maybe you can tell me what can be changed for better rail pressure- afaik there isnt any Magic table which keeps rail pressure stable...

Like stated above it´s a Stage 1 Pump with OEM Inline- Me and a friend had better luck with Stage 1 Pumps than Stage 2, LPFP Pressure is totally stable since installing the Stage 1 whereas it dropped with a Walbro 450 in Bucket.

Fuel is european 102, so no E85 at all!

At the Moment i only changed the pump alone. I tried the following:
Old Pump and OEM Rail (non drilled)= Rail Pressure was even worse
New Pump and OEM Rail (non drilled)= RAil Pressure stable at 15PSI but still dipping at 20PSI.

I will install the drilled Rail again, to see if it helps- when i talk about rail i have a full equipped Rails here with Rail Pressure Sensor, so this means when i Change out the rail i also Change the sensor.

The LPFP Sensor wasn´t Changed, but LPFP seems rock solid so i didn´t think it could be a Problem. I have one here (hopefully the one, which fits) and i can Change it out just to give it a try!
 

Cheezy

Lieutenant
Nov 7, 2016
609
223
0
Toledo Ohio
Check the lpfp feed line into the hpfp, there's a restrictive screen in that connection. You can remove that and increase pressure a little
 

doublespaces

General of the Army
Oct 18, 2016
8,941
4,145
0
AZ
Ride
2009 E93 335i
I have removed those. Wish I didn't. If anyone is taking their out of a new hpfp I'd like to buy them.
 
  • Informative
Reactions: Torgus

doublespaces

General of the Army
Oct 18, 2016
8,941
4,145
0
AZ
Ride
2009 E93 335i
Because its a small price to pay to prevent little crud from clogging an injector causing much worse damage. I have an inline filter but I think it is just easier to leave them in.
 
  • Agree
Reactions: Jeffman and Torgus

zmon1300

Corporal
Nov 3, 2016
181
114
0
Chicagoland
Ride
'10 335xi
Maybe think about getting Port Meth? or VTT Shotgun ? Any of those two will help in terms of Rail pressure, if everything is okay otherwise. Stage 2 turbos ask for alot from both the LPFP and HPFP side of things, you may want to address that.

Good Luck!