LPFP options and possible development.

[GolfRS]

So my LPFP is toast and can't even hold "normal" boost pressures anymore.

I went ahead and got a new CL version OEM pump since it seems it is a "malfunction"
issue rather than a "insufficient volume" issue, and i'll have to see how it does from there.

So the question is what are the options besides the USP solution which i don't really like?

I've seen some individual tries but all seem to run into issues.One is the "starvation issue"
which i don't really comprehend.What is the difference between the OEM pump and the
aftermarket ones that make them starve of fuel ?I mean most are replacing the "core pump"
and not the whole basket so why is there a problem ??Anyone got any schematics that might
be of help ?

I really can't understand how there hasn't been a serious aftermarket LPFP all of this time.
I know we have a returnless fuel system and that the pump is volume controlled by the ECU
but SOMEONE of those big companies should be able to make a pump work the same way and
provide increased volume !!!!

Oh and another thing...If you find your injection duty has gone up lately, better check the
LPFP.Up to now i was under the impression a bad LPFP would normally starve the HPFP and
drop rail pressure but that is NOT the case (at least with a low performing pump like mine was).
Instead the ECU increases injection time to provide the extra fuel but that reaches an end point and
then the problem starts (and it also stresses the injectors).The issue seems to be worse with the S3 injectors that provide less flow in the same rail pressures, so you should be extra careful if using those....

[loudgli]

So my LPFP is toast and can't even hold "normal" boost pressures anymore.

I went ahead and got a new CL version OEM pump since it seems it is a "malfunction"
issue rather than a "insufficient volume" issue, and i'll have to see how it does from there.

So the question is what are the options besides the USP solution which i don't really like?

I've seen some individual tries but all seem to run into issues.One is the "starvation issue"
which i don't really comprehend.What is the difference between the OEM pump and the
aftermarket ones that make them starve of fuel ?I mean most are replacing the "core pump"
and not the whole basket so why is there a problem ??Anyone got any schematics that might
be of help ?

I really can't understand how there hasn't been a serious aftermarket LPFP all of this time.
I know we have a returnless fuel system and that the pump is volume controlled by the ECU
but SOMEONE of those big companies should be able to make a pump work the same way and
provide increased volume !!!!

Oh and another thing...If you find your injection duty has gone up lately, better check the
LPFP.Up to now i was under the impression a bad LPFP would normally starve the HPFP and
drop rail pressure but that is NOT the case (at least with a low performing pump like mine was).
Instead the ECU increases injection time to provide the extra fuel but that reaches an end point and
then the problem starts (and it also stresses the injectors).The issue seems to be worse with the S3 injectors that provide less flow in the same rail pressures, so you should be extra careful if using those....

drop in pumps aside from the apr drop in dont work because they dont fill the basket up in the same way that the oem pump does. there are 2 different styles depending on year but both use a system that is able to fill the basket up regardless of fuel level in the tank. One uses a venturi style/vacumm system. The other uses a seperate port/impeller on the outside of the pump to fill the basket.

pagparts has a pretty decent drop in replacement. Uses an aeromotive pump and a 1 way valve with a metal basket. I dunno if its a perfect solution but should work better than any "drop in" solution.

Ive made up my own assy using a bmw basket that utilizes a 1 way "flapper" in the bottom along with a factory walbro 400. Im still doing testing but it seems to work better than several other solutions ive tried. Its not a "no mods" necessary solution. Took alot of work to get correct fitment.

Still doing some logs with it though. fuel pressure seems lower than with the 044 pump I tried but hpfp logs show a more consistant pressure. Im about to mix everything up though when I switch from my giac 140bar tune to eurodyne 130bar. I am going to try to change the maps on the eurodyne to 140-145bar to maxmize my hardware on pump gas.

[GolfRS]

drop in pumps aside from the apr drop in dont work because they dont fill the basket up in the same way that the oem pump does. there are 2 different styles depending on year but both use a system that is able to fill the basket up regardless of fuel level in the tank. One uses a venturi style/vacumm system. The other uses a seperate port/impeller on the outside of the pump to fill the basket.

pagparts has a pretty decent drop in replacement. Uses an aeromotive pump and a 1 way valve with a metal basket. I dunno if its a perfect solution but should work better than any "drop in" solution.

Ive made up my own assy using a bmw basket that utilizes a 1 way "flapper" in the bottom along with a factory walbro 400. Im still doing testing but it seems to work better than several other solutions ive tried. Its not a "no mods" necessary solution. Took alot of work to get correct fitment.

Still doing some logs with it though. fuel pressure seems lower than with the 044 pump I tried but hpfp logs show a more consistant pressure. Im about to mix everything up though when I switch from my giac 140bar tune to eurodyne 130bar. I am going to try to change the maps on the eurodyne to 140-145bar to maxmize my hardware on pump gas.

I understand there is some sort of "special" OEM design, what i still don't get is why it is so hard for a serious company to COPY it, while still using a larger pump.If it is up to the pump core design, and not the basket arrangement, isn't there a larger pump mimicking that function ?And if it IS the whole basket design....i don't see how it is hard to make something out of plastic nowadays...

In any case i will be dismantling my old pump to see what can be done about it...I'm sure many of you have tried different stuff, but the more minds that think about it the better

P.S.Most probably (as it is the RULE in the aftermarket ) it is not "value for money" for the companies, meaning it costs to make more than it will profit them....Typical...but not stopping me once again....

[loudgli]

I understand there is some sort of "special" OEM design, what i still don't get is why it is so hard for a serious company to COPY it, while still using a larger pump.If it is up to the pump core design, and not the basket arrangement, isn't there a larger pump mimicking that function ?And if it IS the whole basket design....i don't see how it is hard to make something out of plastic nowadays...

In any case i will be dismantling my old pump to see what can be done about it...I'm sure many of you have tried different stuff, but the more minds that think about it the better

P.S.Most probably (as it is the RULE in the aftermarket ) it is not "value for money" for the companies, meaning it costs to make more than it will profit them....Typical...but not stopping me once again....

You'll realize once you take it apart its a fairly complex setup, depending on design and not something that you could duplicate easily. You would have to duplicate the pump size, shape, and features almost identical while trying to add more volume. Or completely redesign the basket altogether with an aftermarket pump and duplicate the level sensor along with the top "lid"

I just doubt theres the money for it. At the power my car is/was making when I started this project I probably didn't even need to upgrade but knew I would at some point to maxmize my pump gas tune.

[GolfRS]

You'll realize once you take it apart its a fairly complex setup, depending on design and not something that you could duplicate easily. You would have to duplicate the pump size, shape, and features almost identical while trying to add more volume. Or completely redesign the basket altogether with an aftermarket pump and duplicate the level sensor along with the top "lid"

I just doubt theres the money for it. At the power my car is/was making when I started this project I probably didn't even need to upgrade but knew I would at some point to maxmize my pump gas tune.

Well fist thing's first, i have to see if the latest "CL" revision is sufficient to my needs.Then
i will get into looking how to improve the low pressure system.

I understand what you are saying about the setup being complex, but that doesn't scare me.
I am pretty resourceful .

I still believe the aftermarket scene has to obey certain profit/quality/etc laws that possibly prohibit the development of such a high flow pump.I also still believe that something might be possible to give
even a bit of extra flow for BT cars.I will take one step at a time....

[thea3kid]

Though the latest revision is "DB" instead of "CL"

[CoNGLoMeRaTeGTi]

OP,

It must suck being banned from GOLFMKV.com.

We are all experimenting with several LPFP options.

From 044s, Aeromotives, and one guy is running a modded BMW pump that hasn't gone under 3 bar yet.

Good luck.

[GolfRS]

OP,

It must suck being banned from GOLFMKV.com.

We are all experimenting with several LPFP options.

From 044s, Aeromotives, and one guy is running a modded BMW pump that hasn't gone under 3 bar yet.

Good luck.

Doesn't really suck...I can still read everything so...LOL.

There are cases though when i could have helped someone and i didn't/couldn't.
So that is the forum's loss not mine...Some might say that is a good thing though...LOL
I could have opened a new account if i wanted to..So many others do it...
But i wouldn't like to keep posting in a censored forum so it's for the best.

So no it doesn't suck.

As for the pump issue, i just swapped my old one for the CL one, and first impressions are good.
I believe the rear pump has been left out of the aftermarket for too long, and seeing what effects a
BAD pump has/had, i believe someone should step forward.I am also experimenting with something but i want to see the difference between a good/working pump vs an old/malfunctioning one before
i go ahead and do what i plan on doing.If i have enough fuel with this new OEM pump i will reconsider if it makes sense pursuing a higher flowing one...There might actually be an injector/rear pump relationship that could fix the "big injector" issue...

Let's see....

[GolfRS]

Well i just did a log pull and i honestly don't know if i should be happy or sad....

There was ZERO difference (well maybe just a bit but only down low) with the
new pump....

It goes all the way to max 91.8% just like the older pump did...SUCKS...

Now the "fun" begins...How to make a rear pump that flows more...Hmmm...

As for those that are running the BMW pumps...Did you guys ever check the
pump load on block 231 ??Cause i'm also at 3 bar @ redline but the pump is MAXED OUT..
Is this how it is supposed to run ???

Please make some logs of the rear pump load and post them up...Just curious....

[loudgli]

Well i just did a log pull and i honestly don't know if i should be happy or sad....

There was ZERO difference (well maybe just a bit but only down low) with the
new pump....

It goes all the way to max 91.8% just like the older pump did...SUCKS...

Now the "fun" begins...How to make a rear pump that flows more...Hmmm...

As for those that are running the BMW pumps...Did you guys ever check the
pump load on block 231 ??Cause i'm also at 3 bar @ redline but the pump is MAXED OUT..
Is this how it is supposed to run ???

Please make some logs of the rear pump load and post them up...Just curious....

I use like 103 for lpf pressure. Is that different than 231? Whats this %? calculated duty cycle? would a non factory pump calculate correctly? my bmw walbro 400 is reading ~3.8-9 bar at redline. The 044 was slightly higher but my hpfp logs are more consistant now. This pump has to have the capacity (its used on bmw's 5L TT V8) but whether the controller can utilize it correctly I dunno... my car currently only makes about 350whp. Im about to swap the majority of my hardware out along with switching to eurodyne so Ill know whether the pump can support higher hp here pretty soon.

[GolfRS]

I use like 103 for lpf pressure. Is that different than 231? Whats this %? calculated duty cycle? would a non factory pump calculate correctly? my bmw walbro 400 is reading ~3.8-9 bar at redline. The 044 was slightly higher but my hpfp logs are more consistant now. This pump has to have the capacity (its used on bmw's 5L TT V8) but whether the controller can utilize it correctly I dunno... my car currently only makes about 350whp. Im about to swap the majority of my hardware out along with switching to eurodyne so Ill know whether the pump can support higher hp here pretty soon.

Block 231 has the pump duty cycle and the pressure too.

I wouldn't mind working the pump 100% if i knew it wont go boom on me soon...

Also the high injection time tells me that even at full capacity the pressure produced is not enough to
lower the inj. time so....the pump is not working as it should...

As for the aftermarket pumps, i cant be certain, but i believe if it is still ECU controlled it should at least show what the ECU is demanding of the pump, if anything.

Log block 231 and see....

[loudgli]

Block 231 has the pump duty cycle and the pressure too.

I wouldn't mind working the pump 100% if i knew it wont go boom on me soon...

Also the high injection time tells me that even at full capacity the pressure produced is not enough to
lower the inj. time so....the pump is not working as it should...

As for the aftermarket pumps, i cant be certain, but i believe if it is still ECU controlled it should at least show what the ECU is demanding of the pump, if anything.

Log block 231 and see....

What do you consider high injection time?

I would think that for a correct duty cycle the ecu would need to know maximum output of the pump. the only thing I can think where this wouldn't be true is if it's using voltage output to calculate duty cycle.

Example.

I think the pump controller maxes out at about 12v. If a stock pump has to be ran at 12v to supply correct fuel then it's at 100%. If aftermarket pump only needs to run at 9v then it's 75%. Just an idea. Had i known about 231 I would have logged this with my different setups but I didn't. My car is down again right now. Hopefully have it back up this weekend and I'll do some more logging to compare.

Sent from my Galaxy Nexus

[GolfRS]

What do you consider high injection time?

I would think that for a correct duty cycle the ecu would need to know maximum output of the pump. the only thing I can think where this wouldn't be true is if it's using voltage output to calculate duty cycle.

Example.

I think the pump controller maxes out at about 12v. If a stock pump has to be ran at 12v to supply correct fuel then it's at 100%. If aftermarket pump only needs to run at 9v then it's 75%. Just an idea. Had i known about 231 I would have logged this with my different setups but I didn't. My car is down again right now. Hopefully have it back up this weekend and I'll do some more logging to compare.

Sent from my Galaxy Nexus

High injection time is seen with the injectors actually "flat lining" and unable to maintain the
requested AFR.Since our system is ECU regulated, i believe when the ECU is seeing lack of fuel
from one of the components (the LPFP in this case) it does the only thing it can which is to increase
the injection time (since the pump is already maxed out).At first i thought this would also show in the
rail logs as a drop in pressure, but this was not the case (why is whole other story...).

In any case, what you are thinking about the voltage is correct (at least i agree with you) but keep in mind our low pressure system is "adaptable" and there might be some coding that determines what is
the "proper voltage" for the OEM pump, and any deviation might not seem nice to the ECU (as you put it you don't know if it is cooperating...

Another thing is that low pressure is dependent on the AMOUNT of fuel injected.If the fuel needed is a lot, even your pump might reach the 3 bar limit.As you said you are still at 350whp and that might be sufficient for the pump...I wouldn't rush to judgement and keep a pump for a "BT intank pump".Once you go bigger, you might see what we all see right now...

[loudgli]

High injection time is seen with the injectors actually "flat lining" and unable to maintain the
requested AFR.Since our system is ECU regulated, i believe when the ECU is seeing lack of fuel
from one of the components (the LPFP in this case) it does the only thing it can which is to increase
the injection time (since the pump is already maxed out).At first i thought this would also show in the
rail logs as a drop in pressure, but this was not the case (why is whole other story...).

In any case, what you are thinking about the voltage is correct (at least i agree with you) but keep in mind our low pressure system is "adaptable" and there might be some coding that determines what is
the "proper voltage" for the OEM pump, and any deviation might not seem nice to the ECU (as you put it you don't know if it is cooperating...

Another thing is that low pressure is dependent on the AMOUNT of fuel injected.If the fuel needed is a lot, even your pump might reach the 3 bar limit.As you said you are still at 350whp and that might be sufficient for the pump...I wouldn't rush to judgement and keep a pump for a "BT intank pump".Once you go bigger, you might see what we all see right now...

I should have been more clear. What injector timing numerically do you consider high?

According to several sources I've found, this walbro pump flows fairly similar to a 044 pump. But everything looks completely different when it's installed in the car. (from variances in pressure and voltage at idle and load to different high pressure constants) and i don't mean the numbers are different but the controller seems to control then completely different. That's why I wish I understood more how the fuel pump controller works along with its interaction with the hpfp and injectors. more testing will eventually show us maybe not how it works but what works.

Sent from my Galaxy Nexus

[GolfRS]

Are you asking about absolute numbers ?

The FSI injectors have very different injection times than the older ones.

To give you an example i was seeing ~10 ms on the S3 injectors when i maxed them out,
and i am seeing 8.9 ms with the RS4's...But the two injectors are different, so i am
guessing that is the max they work at...

Btw, how much a rear pump can "support" a setup depends heavily also upon the
AFR one wants to run...It's completely different running 0.77-0.80 and 0.83.
Puts much more strain on the fueling system.

So please make a few logs on block 231 with your pump...I'm curious...

[loudgli]

Are you asking about absolute numbers ?

The FSI injectors have very different injection times than the older ones.

To give you an example i was seeing ~10 ms on the S3 injectors when i maxed them out,
and i am seeing 8.9 ms with the RS4's...But the two injectors are different, so i am
guessing that is the max they work at...

Btw, how much a rear pump can "support" a setup depends heavily also upon the
AFR one wants to run...It's completely different running 0.77-0.80 and 0.83.
Puts much more strain on the fueling system.

So please make a few logs on block 231 with your pump...I'm curious...

yeah absolute numbers.

Ive never seen more than high 6's on RS4's on my car @ .79-.80 afr

But then again I dont know what pressure your car runs at either. Mine originally was 132 but now is 140.

ill put some logs together of different setups Ive had. I found a couple older ones where I did use 231. not sure when/why i went to 103.

[GolfRS]

yeah absolute numbers.

Ive never seen more than high 6's on RS4's on my car @ .79-.80 afr

But then again I dont know what pressure your car runs at either. Mine originally was 132 but now is 140.

ill put some logs together of different setups Ive had. I found a couple older ones where I did use 231. not sure when/why i went to 103.

As i said above rail pressure plays a big role, as well as the amount of fuel needed by the ECU.

One think that no one has mentioned ever, and it opened my eyes as far as the importance of the rear pump is that rail pressure ISN'T an indication of the available FUEL quantity...It may sound strange
but the way i see it you can pressurize a certain QUANTITY of fuel to a certain PRESSURE but that doesn't guarantee the amount of fuel pressurized.If you think about the internal volume of the pump you can fill all of that space (with a good and powerful rear pump) and pressurize it to lets say 130 bar, but you can also pressurize SMALLER volume (cause the rear pump can't keep up) to the SAME RAIL PRESSURE but you would have LESS FUEL....

Don't know if i am making this clear enough, if someone doesn't understand i can try and explain it better...Overall what it comes down to is the rear pressure system is vital to the QUANTITY of fuel present and pressurized (to the requested pressure), but it may not effect the pressure itself (well maybe until it is too late...).So rail pressure should not be an indication the rear pump is functioning properly.There is a difference between not being able to pump fuel and not being able to simply keep up....

[loudgli]

This would be the most current setup.

This was same setup but with 142frv

Bosch 044 with 142frv

[GolfRS]

Ill edit this when I get more graphs made up. This would be the most current setup.

Kind of a difficult graph to follow, but from what i can tell your low pressure is around 4 bar and holding
which is good but not all that good cause your injector timing seems also high (for a K04 that is).
From what i have seen on the OEM pump until the 5000-5500 mark the pump makes upwards of 4.5 bar and then drops to 3 bar at 7000, but that again is with the BT and 130 bar of requested pressure.

Once again don't take rail pressure as a measure of the low pressure health because it isn't...

Other than that it looks ok, but i really doubt it can hold the flow of a BT setup, seeing that your injection time is a little under 8 ms (if i am reading this correctly) and as i've seen the RS4's seem to max at high 8's...

What about the pump load ?Do you have that ?

[loudgli]

Kind of a difficult graph to follow, but from what i can tell your low pressure is around 4 bar and holding
which is good but not all that good cause your injector timing seems also high (for a K04 that is).
Current setup is GT2871R
From what i have seen on the OEM pump until the 5000-5500 mark the pump makes upwards of 4.5 bar and then drops to 3 bar at 7000, but that again is with the BT and 130 bar of requested pressure.

Once again don't take rail pressure as a measure of the low pressure health because it isn't...
If you look at both graphs its obvious that with the higher pressures w/ the new frv that the low pressure pump has slightly lower pressure. So there is a correlation

Other than that it looks ok, but i really doubt it can hold the flow of a BT setup, seeing that your injection time is a little under 8 ms (if i am reading this correctly) and as i've seen the RS4's seem to max at high 8's...

Injection time never went above 7.15...not saying thats great but...

What about the pump load ?Do you have that

looking for my older logs, give me a minute

[GolfRS]

Current setup is GT2871R

Yeah, well that would explain the injection timing then, but as i said there is that RS4 limit, and 7.15 isn't that great as you said.On what boost are you at the moment ? That also plays an important role trying to maintain AFR.

If you look at both graphs its obvious that with the higher pressures w/ the new frv that the low pressure pump has slightly lower pressure. So there is a correlation

You didn't understand me.Of course there is a correlation between how much rail pressure you run and how the low pressure lowers cause the pump is trying harder to compensate.What i said was having a good/stable rail pressure isn't proof you are also having the fuel you need, hence the high injection time.It's a little paradox and hard to understand cause in TFSIland we have connected rail pressure to fuel amount, and that simply ISN'T SO...

Injection time never went above 7.15...not saying thats great but...

Once again it depends in what boost you are running (and what turbo for that matter).
More air demands more fuel, and the low pressure is the WEAK link...

[mrbikle]

how about running the 044 on off a voltage/amperage repeater box inline after the in take but before the fuel filter?

thats how the 1.8t guys do it.... the setup is good for ~700whp

[GolfRS]

how about running the 044 on off a voltage/amperage repeater box inline after the in take but before the fuel filter?

thats how the 1.8t guys do it.... the setup is good for ~700whp

I had in mind to use an inline pump with some sort of pressure switch (is this how USP is doing it ?)
to have it activate when pressure drops bellow 4 bar for example, but i am pretty sure
since the rear pump is ECU controlled i'm gonna run into issues...

Besides i have always been a fan of OEM.

One thing that puzzles me though is that i see ~5 bar at idle and for all i know our pumps (just like the 225 1.8T pumps before) are 4.0 bar pumps.And i am not talking about pressure at throttle lift.
What is up with that...I also saw i big difference after going to the CL pump performance wise up to ~5000 rpm...After that it had no difference to my old pump...

[loudgli]

Updated w/ bosch 044 setup. As you can easily see the 044 supplies a decent amount more pressure starting out but only sits about 1/2-3/4 bar higher at higher rpms

Yeah, well that would explain the injection timing then, but as i said there is that RS4 limit, and 7.15 isn't that great as you said.On what boost are you at the moment ? That also plays an important role trying to maintain AFR.

I believe all these logs are at 24-25psi.

You didn't understand me.Of course there is a correlation between how much rail pressure you run and how the low pressure lowers cause the pump is trying harder to compensate.What i said was having a good/stable rail pressure isn't proof you are also having the fuel you need, hence the high injection time.It's a little paradox and hard to understand cause in TFSIland we have connected rail pressure to fuel amount, and that simply ISN'T SO...

You're right I guess I dont fully follow. I know my previous 044 was able to supply more fuel than it was putting out. It ran at like 8 volts compared to the APR LPFP drop in which ran at like 12volts. So why wouldn't the hpfp have an easier time of creating requested pressure along with the injectors being able to lower injector timing?


Once again it depends in what boost you are running (and what turbo for that matter).
More air demands more fuel, and the low pressure is the WEAK link...

I think the lpfp controller along with tuning has something to do with this "weak" link and not necessarily just the pump itself as Ive explained my reasoning above.

In a perfect world I would attempt to use the 044 with this newer 155frv to see how that effects injector timing. But Ive abandoned using the 044 for now because I cant get it to work with any baskets that dont cause starvation issues.

[loudgli]

It goes all the way to max 91.8% just like the older pump did...SUCKS...

For reference sake. Ive found several logs with different tune variations/boost variations/low pressure pumps that Ive ran in the past and they all log 91.8% on block 231. Im not convinced that really means what we think it means. just a thought.

[GolfRS]

For reference sake. Ive found several logs with different tune variations/boost variations/low pressure pumps that Ive ran in the past and they all log 91.8% on block 231. Im not convinced that really means what we think it means. just a thought.

The thing is...is that maxed state "expected" ?

Something like a "throttle body" going to WOT ?

Is it detrimental to the pump's function ?
Or is it supposed to max out ??

And if so, why are the injectors maxed too ?

Don't know the answers to those questions....

[loudgli]

The thing is...is that maxed state "expected" ?

Something like a "throttle body" going to WOT ?

Is it detrimental to the pump's function ?
Or is it supposed to max out ??

And if so, why are the injectors maxed too ?

Don't know the answers to those questions....

Id bet money if I reinstalled the 044. Ran 231 it would show 91.8%. I could test voltage and it will probably show ~8v under wot when I know the controller is able to supply 12v. maybe amperage is a factor?

I not know.

[GolfRS]

Id bet money if I reinstalled the 044. Ran 231 it would show 91.8%. I could test voltage and it will probably show ~8v under wot when I know the controller is able to supply 12v. maybe amperage is a factor?

I not know.

Well LPFP programming is unknown territory...For all i know there might be
coding that could help with the flow of the pump, just hasn't been looked into yet,
and we (the consumers) are struggling with hardware.

It's is not even clear what this 91.8% really means.Does it correlate to pump voltage ?
Does it correlate to percentage of flow RELATED to actual requested low pressure values ?
Meaning is it hitting max requested pressure ?Would a different coding actually increase the
flow (short of like the torque limit on the DSG or the targeted engine torque by the ECU) ?
We could go as far as say the pump controller itself might need to be tampered with....

It's all a mystery....

[kevin160]

My 044 doesn't go much over 70%.

[GolfRS]

My 044 doesn't go much over 70%.

What is your setup, your rail pressures and your injection times ?

[kevin160]

My setup. http://forums.vwvortex.com/showthrea...GTX3071r-build

I'll have to check my logs. I just got a 155 frv. So the highest pressure i've run is 135.

[loudgli]

Id bet money if I reinstalled the 044. Ran 231 it would show 91.8%. I could test voltage and it will probably show ~8v under wot when I know the controller is able to supply 12v. maybe amperage is a factor?

I not know.

fixed my car today.
ran a 231 log. I guess I was wrong. my walbro runs alot less than 91%

I re-installed the rs4 frv. I dont like seeing that >150bar pressure.

[GolfRS]

fixed my car today.
ran a 231 log. I guess I was wrong. my walbro runs alot less than 91%

I re-installed the rs4 frv. I dont like seeing that >150bar pressure.

See this just confirms my hypothesis and something that has not been told before in the TFSI tuning scene.

That the rear pump is far more important than previously thought in how the INJECTORS provide enough flow for BT setups, and even more how another forum member was able to make 520 whp with just a rear pump upgrade....

Your injection time is also in agreement with this theory.

This proves how important is for a company to come up with a SERIOUS OEM like rear pump for the
TFSI platform.....

[mrbikle]

That's old news, just not overly public.

Sent from my SPH-D710 using Tapatalk

[GolfRS]

That's old news, just not overly public.

Sent from my SPH-D710 using Tapatalk

I don't believe it's old news as you say cause i am also referring to K04 setups that
might be experiencing high duty cycle and have upgrated to RS4's to cope.

Up to now what was "old news" was the fact the rear pump supports a certain HP and
above that you need something more.Things show even with lower HP if your rear pump is
going you might be starving of fuel and the ECU is just covering it up by increasing the
injector time.THAT is not old news....