[Reckless335]

Ok, so my stock LPFP was dipping super low (lowest I saw was 35) so I ordered an upgrade (decided to go with Boost Concepts after a long debate between them and the Fuel-It stage 2. Anyways, I get the pump in the mail and install it via the online instructions. Everything is good to go. However, my LPFP isn't doing any better. I'm still seeing it dip as low as 47psi. This thing is a brand new Walbro 450 certified for e85. (Which, I haven't even run yet, btw) I'm running straight 93 octane. Any idea why my LPFP psi is still dipping below 60? Before anyone asks, I haven't had a chance to log yet. Weather has been rainy lately. Someone said it could be the LPFP sensor? And someone else said it might be the EKPM? Any way to check either of these things to see if they're bad? The problem only happens under load. At idle my psi is 72.5 as it should be, and driving normally it's ok. It's only when I go WOT that it dips. Anyone experience anything like this or know what it could be?

[Jeff@TopGearSolutions]

Most people at this point suggest the LPFP sensor is toast, that would be your next step.

Wish I knew a way to test.

[bluemonstr]

If you haven't already I'd be talking to Chris at Boost concepts. He can probably give you better answers than any of us. He's super helpful and knows LPFP's like no one's business. Personally, I got my LPFP from him and was able to install and have been able to run more E85 than I can play with at the moment never seeing below 68psi since.

I'd guess that maybe you have a line that is leaking or not sealing/connecting correctly inside your tank or something (or sensors failing giving bad readings as mentioned above)...but that is just a WILD guess.

[csu87]

Like Jeff said, probably the sensor. Especially if you arent running e85 and its a new pump.

http://www.e90post.com/forums/showthread.php?t=1278339

[Reckless335]

So, I finally got around to being able to take some logs. I'm still kinda new to reading logs, but from what I see, they don't look good

Please excuse the first half of the first log. I was on the highway, and right as I pushed the button to start logging, I thought I saw the man.....turns out it wasn't him, so I continued to log.

http://datazap.me/u/latino1ny/cobb-s...og=0&data=3-13


Second log I logged STFTs and LTFTs along with my LPFP which, ironically only dipped to exactly 60 during the log

http://datazap.me/u/latino1ny/cobb-s...og=0&data=3-11

Actually, after adding ethanol I started noticing similar behavior with my setup as well.

Specs:
2007 E90 BMW 335i (Automatic) ~86k miles
7" VRSF FMIC
VRSF Catless Downpipes
MHD 7.1 OTS E40 tune (current mix in the fuel tank is around ~E50)

The following parts have less than ~5k miles on them:
NEW HPFP
NEW Index 12 injectors (all 6)
NEW Fuel-It! Stage 2 LPFP
NEW LPFP sensor/fuel line (latest revision - 13537622751)
NEW Primary O2 sensors

In the log below you'll see that the LPFP readings dip well into the low 50's; even as low as 49 psi. Same trend continues even after resetting all adaptations, etc.:
http://datazap.me/u/fcobra94/log-147...22&zoom=79-203

I currently have ~120 miles on the tune and more than a handful of 3rd gear WOT runs. I thought that maybe the LPFP psi figures would adapt upwards, but there's been no change so far and the trend of "low 50s" has continued.

I reached out to Steve from Fuel-It! and these were his thoughts:

Hard to say for sure, it could be due to the drivers side filter (clogged or cracked), EKP, or the DME pulling PWM to the pump. You're also welcome to send it in to be bench tested if you'd like.

The easiest thing to do at this point is swap out the EKP, so I copped a cheap used one on ebay to see if that makes a difference. Will keep you updated.

[Chris@BoostConcepts]

Originally Posted by Reckless335

So, I finally got around to being able to take some logs. I'm still kinda new to reading logs, but from what I see, they don't look good

Please excuse the first half of the first log. I was on the highway, and right as I pushed the button to start logging, I thought I saw the man.....turns out it wasn't him, so I continued to log.

http://datazap.me/u/latino1ny/cobb-s...og=0&data=3-13


Second log I logged STFTs and LTFTs along with my LPFP which, ironically only dipped to exactly 60 during the log

http://datazap.me/u/latino1ny/cobb-s...og=0&data=3-11

As per our offline correspondence, that log looks perfectly normal especially for a recent installation, It may smooth out with time as the DME learns the flow characteristics of the new pump. but as they are they are pretty normal looking. the important factor is to see that they are bouncing high and low which is most commonly due to both the intake pulses of the HPFP and the Fuel pressure regulator opening and closing as the pressure pulses force it open. there will be some mechanical lag that overlaps which is what causes those peaks and valleys.

I wouldn't replace anything at this point!

Originally Posted by FCobra94

Actually, after adding ethanol I started noticing similar behavior with my setup as well.

Specs:
2007 E90 BMW 335i (Automatic) ~86k miles
7" VRSF FMIC
VRSF Catless Downpipes
MHD 7.1 OTS E40 tune (current mix in the fuel tank is around ~E50)

The following parts have less than ~5k miles on them:
NEW HPFP
NEW Index 12 injectors (all 6)
NEW Fuel-It! Stage 2 LPFP
NEW LPFP sensor/fuel line (latest revision - 13537622751)
NEW Primary O2 sensors

In the log below you'll see that the LPFP readings dip well into the low 50's; even as low as 49 psi. Same trend continues even after resetting all adaptations, etc.:
http://datazap.me/u/fcobra94/log-147...22&zoom=79-203

I currently have ~120 miles on the tune and more than a handful of 3rd gear WOT runs. I thought that maybe the LPFP psi figures would adapt upwards, but there's been no change so far and the trend of "low 50s" has continued.

I reached out to Steve from Fuel-It! and these were his thoughts:


The easiest thing to do at this point is swap out the EKP, so I copped a cheap used one on ebay to see if that makes a difference. Will keep you updated.

There is a vast difference in your logs and Reckless335's, yours are not recovering, they are a steady fall meaning you are not flowing enough to maintain a mean targeted pressure. I would test your voltage at the pump under full load. if you are seeing max system voltage 13.5v+ under load then the issue is a mechanical problem. its tricky to test and requires two people really unless doing it on a dyno. don't need to be watching a volt meter and trying to reign in the car while accelerating, so be safe in your testing and use a buddy to watch the voltage output to the pump on the multi-meter.

If the pump output is not achieving max system voltage, then the issue lies in a component (Fuel Pump Module, DME, harness, plug etc..) or in the fuel pump control mapping. in the case of the link you posted previously for mojobmw_e90, he was seeing different pressures based on different tunes he flashed which leads me to believe that there is a potential link in the DME for the tables being used to tune with and the fuel pump PWM output control table(s). Because some tuners do not share access to their tunes it is hard to decipher what changes are being made to what tables that may potentially be causing this to happen (if it actually is).

As mentioned the first step is determining if the issue is pre-pump, the pump, or post pump.

Hope this helps!

Chris

Very much appreciated!

After scouring a few LPFP related issue threads, I had planned on doing exactly that; having a friend read voltage @ the pump during a pull. I noticed that EKP issues were somewhat common though and since they're fairly cheap, figured I'd pick one up and keep it on the shelf anyway "just 'cause."

Either way, thanks very much for offering your expertise!

[mojobmw_e90]

Originally Posted by Chris@BoostConcepts

As per our offline correspondence, that log looks perfectly normal especially for a recent installation, It may smooth out with time as the DME learns the flow characteristics of the new pump. but as they are they are pretty normal looking. the important factor is to see that they are bouncing high and low which is most commonly due to both the intake pulses of the HPFP and the Fuel pressure regulator opening and closing as the pressure pulses force it open. there will be some mechanical lag that overlaps which is what causes those peaks and valleys.

I wouldn't replace anything at this point!





There is a vast difference in your logs and Reckless335's, yours are not recovering, they are a steady fall meaning you are not flowing enough to maintain a mean targeted pressure. I would test your voltage at the pump under full load. if you are seeing max system voltage 13.5v+ under load then the issue is a mechanical problem. its tricky to test and requires two people really unless doing it on a dyno. don't need to be watching a volt meter and trying to reign in the car while accelerating, so be safe in your testing and use a buddy to watch the voltage output to the pump on the multi-meter.

If the pump output is not achieving max system voltage, then the issue lies in a component (Fuel Pump Module, DME, harness, plug etc..) or in the fuel pump control mapping. in the case of the link you posted previously for mojobmw_e90, he was seeing different pressures based on different tunes he flashed which leads me to believe that there is a potential link in the DME for the tables being used to tune with and the fuel pump PWM output control table(s). Because some tuners do not share access to their tunes it is hard to decipher what changes are being made to what tables that may potentially be causing this to happen (if it actually is).

As mentioned the first step is determining if the issue is pre-pump, the pump, or post pump.

Hope this helps!

Chris

Yes and no Chris. So many changes was made on my car via tuning and mechanical stuff being replaced that at the end of the day nothing helped bring the psi up into the 60s other than a s1 inline. I was not seeing changes on my fuel pressure even while switching maps. I drove around 200 miles on stock map, jb4 on map 0,stock backend flash and still didn't make a diffrence. I even tried the backend flash that's on n54tech.com and that didn't help either. So it might not be tune relayed at this point as if you recall my brother also has a 335xi and he also has custom tuning done by the same gentleman and his pump sits at 75psi idle. And that pump in his car came out of my car and I got a brand new unit.

[Chris@BoostConcepts]

Originally Posted by mojobmw_e90

Incorrect Chris. I was not seeing changes on my fuel pressure even while switching maps. I drove around 200 miles on stock map, jb4 on map 0,stock backend flash and still didn't make a diffrence. I even tried the backend flash that's on n54tech.com and that didn't help either. So it might not be tune relayed at this point as if you recall my brother also has a 335xi and he also has custom tuning done by the same gentleman and his pump sits at 75psi idle. And that pump in his car came out of my car and I got a brand new unit.

Perhaps I misunderstood what you meant in your email, but you stated "Today I loaded up a mhd jb4 backend flash and my idle psi is back up to 63psi" this was the last bit of information you sent regarding the troubleshooting you were performing. Obviously I was not present for the testing, and only have to go on the information you provided, but I put this in my notes with an asterisk as an important piece of information. if it isn't correct please let me know and I will strike it from my list of potential items to investigate.

Thanks Mojo!

Chris

[Chris@BoostConcepts]

Originally Posted by FCobra94

Very much appreciated!

After scouring a few LPFP related issue threads, I had planned on doing exactly that; having a friend read voltage @ the pump during a pull. I noticed that EKP issues were somewhat common though and since they're fairly cheap, figured I'd pick one up and keep it on the shelf anyway "just 'cause."

Either way, thanks very much for offering your expertise!

I don't know if I would call the Fuel Pump Module (EKP) cheap.. unless you are looking at used ones, and if you are, be careful as you never know the condition of those.

Please update with your voltage test results! I have a feeling that these odd instances will become more common going forward as the cars continue to age and any and all information pooled in one place helps the community!

Chris

[Martijn]

I have a similar problem.
I have a stage 2 lpfp from fuel it.
I've changed almost everything.
Brand new ekp with a full dme update at the dealer.
New lpfp sensor
New filter at the drivers side.
Reset adaptations
Still no luck. My stage 2 keeps dropping hard.
Even to the point it throws me on map 4 because of lean fuel mix.
I'm running e35 so nothing special.

Post logs if you have them.

[Martijn]

Yes I do.

http://datazap.me/u/martijn/lpfp-che...a=1-4-17-18-24

Here is the log.

I used to run 23-24psi. The lpfp was pretty low but it managed. Now it's absolutely terrible.
Map 1 is Allready giving trouble.

My setup is : fbo,inlets, pure stage 2 turbo, Stage 2 lpfp, Meth dual nozzle cm10 +5.

Originally Posted by Chris@BoostConcepts

There is a vast difference in your logs and Reckless335's, yours are not recovering, they are a steady fall meaning you are not flowing enough to maintain a mean targeted pressure. I would test your voltage at the pump under full load. if you are seeing max system voltage 13.5v+ under load then the issue is a mechanical problem. its tricky to test and requires two people really unless doing it on a dyno. don't need to be watching a volt meter and trying to reign in the car while accelerating, so be safe in your testing and use a buddy to watch the voltage output to the pump on the multi-meter.

So I was able to get under the rear seat for a bit today and attempt the last half of this test procedure:
http://www.pelicanparts.com/BMW/tech...mp_Testing.htm

Unfortunately the probes on my volt meter are way too fat to fit between the wires and the insulator on the LPFP power harness, so backprobing is out of the question; unless someone has any other ideas on how this can be done safely.

What I did instead was disconnect the power harness from the LPFP altogether and run the volt meter leads directly into the harness itself to get the following values while the car was not running:
- key on = 1.733V
- flashing a map via MHD = 12.06V
- Fuel-It HOW TO: VERIFY YOUR FUEL SYSTEM USING INPA = 11.99V / fuel control valve test = 5667hPa-5700hPa (~82psi)

*all testing was done with a 2A battery charger connected*

It's obvious that testing voltage under load is a necessary step, I just don't know how that can be done on this particular harness. Furthermore, how is there no option for INPA to tell you how much voltage the EKP is sending to the pump to begin with?!

[Donutz]

Can you fashion something conductive that will fit between the wire and insulator? If you can find something to extend the voltage signal, you could use alligator clips to attach your leads. Then use a video camera to record your volt meter while you drive. You just have to figure out how to secure all the gear so it isn't flying around (risk of shorting if you aren't careful).

Originally Posted by Donutz

Can you fashion something conductive that will fit between the wire and insulator? If you can find something to extend the voltage signal, you could use alligator clips to attach your leads. Then use a video camera to record your volt meter while you drive. You just have to figure out how to secure all the gear so it isn't flying around (risk of shorting if you aren't careful).

Yeah, I considered that as well...building a set of "jumper" wires just doesn't sound appealing to me at the moment lol

[Chris@BoostConcepts]

I use a jumper plug harness I made from an old top hat and harness plug, but I understand not everyone has access to those parts randomly laying around.

I brainstormed on how you could probe it, I would imagine sewing pins with the plastic ball heads are small enough to slip down in and used alligator clips on them with electrical tape to hold everything in place and insulate the leads from each other and anything potentially offering a ground path.

You could also use wire strippers to open a small section inside the cabin before the harness plug without damaging the conductor, reinsulating afterwards would require some close attention, I would use liquid electrical tape and regular electrical tape combines to ensure a good seal. This portion is inside the car and would not be exposed to the elements so it's mainly for short prevention.

Chris

[Martijn]

Even if you find a voltage problem . What can you do about it?

[Chris@BoostConcepts]

Start working back towards the DME to find what is creating the issue. It gives you a direction to work towards.

[mojobmw_e90]

Originally Posted by FCobra94

Yeah, I considered that as well...building a set of "jumper" wires just doesn't sound appealing to me at the moment lol

U can use 2 alligator clips and than taping the clips to the wires so it doesn't move around or ground out