N54 having LPFP spikes over 110psi!

[alvinhobh]

N54 having LPFP spikes over 110psi!

2007 335i e92
Fuel-it stage 3 LPFP
550 cc PI
AIC2
Motiv- FF sensor
Running e85

In the process of tuning my car, noticed the LPFP pressure was all over the place, dropping below 40 and spikes over 100psi, so I decided to replace the following:

HPFP ( FCP lifetime warranty so why not)
HPFP sensor
LPFP sensor
Both LPFP filters
Driver side tank filter/ regulator tank
Removed and blocked off the stock FPR
Install an external FPR
Replaced the EKP ( used on from Ebay, coded with protool)

Pressure doesnt drop as lowe as before but still like crazy spikes! Tuner is working with me on this, giving me above and beyond support. He lowered the boost target so we can how things behave and I don't need help on analyzing anything in the log, but I wanted to put it out here and see if anyone has ever experienced the same issue with the LPFP spikes.

Hide legend Reset zoom

 

[sch4400]

The damper needs to be where B is or Z

FPR is has to be on the return line same position as in pic and lpfp sensor is on the FPR reference port.

if you have a flex sensor it can be anywhere it really doesn't matter A or Z position.

well..
should it connect boost line to damper ???

 

[martymil]

Big NO as our fuel pressure is static

 

[sch4400]

Big NO as our fuel pressure is static

well..
I just saw it.
is it working ??

Big Thank you for helping me out.

 

[bakerdou]

On the dead head system you want the LPFP sensor on the reference port of the FPR opposite the return line and the damper at A

Bypass FPR you want the LPFP sensor on the reference port of FPR and damper at Z

Do not connect boost line to FPR on either system.

Sorry about my being verbose but I found Radium carries a FPR-Damper integrated product, link to it as follows.

May I assume that if I install this prior to the HPFP, and mount the fuel pressure sensor to its reference port, it matches your description about the dead head system? Do need to make other modifications besides the removal of stock FPR?

 

[martymil]

Just run a return line from the fpr and that's it, I do prefer running in separately as you can mount the damper right near the pump where its most effective and the fpr under the car just after the ethanol sensor where its usually mounted.

I extend the wiring for the LPFP sensor to move it as far away from the HPFP as possible but on the fpr pressure reference point.

 

[marseille]

Does anyone know if either of these LPFP sensors is 1/8 NPT? I'm installing this into a Radium FPD in the NPT port.

FCP Euro - New style (silver color)

FCP Euro - Older style (brass with o-ring)