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RS4 Fuel return valve

111K views 207 replies 49 participants last post by  0-60Motorsports 
#1 ·
Any one else tried this?
The RS4 valve can cope with up to 150bar of pressure requests
a must for stage 2+ cars with flat spots at 5k where more fuel is requested
 
#127 ·
Re: FV-QR (GolfRS)

Quote, originally posted by GolfRS »

Emmm...actually no.The issue with stock injectors and K03 vs a K04 is not the mid/high torque area, but the top/maximum power.As with a K03, the K04 can be covered by a HPFP and stock injectors (of course you'd have to limit the torque to K03 levels, but that is not THAT far away from a K04 with "normal" peak boost requests.
On the other hand stock GTI injectors can only support up to ~300 crank HP till they run out, and since (if you haven't noticed you can check it out yourself also) max rail pressure is attained at the highest revs, the ECU has the ability to overcome the requested pressure by almost +5bar for a certain range if it sees issues with top rev fueling.
If someone has a different experience do come forth...

you still sound a little confused. You've got to separate the injectors, hpfp, and pressure regulator valve into different categories and realize they all have different fueling limits at different parts in the poweband.
The stock injectors will not get maxed out till the top end when the hpfp is supplying plenty of fuel but the injectors can no longer flow any more. This is why an S3 will use the same stock hpfp as the A3 and GTI but need upgraded injectors.
The stock hpfp will first get maxed out in the low end (high torque area) when the engine is not reving fast enough to drive the fuel pump fast enough. The stock injectors are no where near being maxed out here.
The stock fuel pressure regulator valve maxes out at (in my case) ~127bar at the top end when enough fuel can be supplied by the hpfp and where the RS4 injectors can still keep up. So upgrading the valve prevents pressure dump while the other components are still capable of keeping up
 
#128 ·
http://www.genuinevwaudiparts....14407
Mechanical Catalog
Item Number MSRP Core Price Price
079130757 $97.50 $0.00 $70.20
Fuel system - Fuel induction - Fuel injection - Fuel pressure regulator
Fuel pressure regulator, r8 2008
This is the part we are looking for?
Is this the correct part to order from this website?
 
#130 ·
I had the same problem.
 
#131 ·
Re: FV-QR (ndifadvokit)

Quote, originally posted by ndifadvokit »

you still sound a little confused. You've got to separate the injectors, hpfp, and pressure regulator valve into different categories and realize they all have different fueling limits at different parts in the poweband.

Oh believe me i am very well aware of what i am saying.Not the slightest bit confused.Injectors, and rail pressure are DIRECTLY related when it comes to fuel delivery.Pump is just the means to get them going.If our direct injected engines where not capable of such low end torque, the pump would be out of the picture as far as "aftermarket" goes.Rail pressure on the other hand along with injector flow is what makes the top end power.
Quote »

The stock injectors will not get maxed out till the top end when the hpfp is supplying plenty of fuel but the injectors can no longer flow any more. This is why an S3 will use the same stock hpfp as the A3 and GTI but need upgraded injectors.
The stock hpfp will first get maxed out in the low end (high torque area) when the engine is not reving fast enough to drive the fuel pump fast enough. The stock injectors are no where near being maxed out here.

Wait..are you just repeating what i wrote you above ?Or are you trying to make others understand better ?Weird...There must be an echo in here...

Quote »
The stock fuel pressure regulator valve maxes out at (in my case) ~127bar at the top end when enough fuel can be supplied by the hpfp and where the RS4 injectors can still keep up. So upgrading the valve prevents pressure dump while the other components are still capable of keeping up

See this is what you are not getting...The stock Gti valve is good for 130 bar.NOTHING gets dumped until that limit is reached.That's why it is called a LIMITING VALVE.It LIMITS pressure to 130 bar.That means that since you are not even reaching 127 bar, your stock valve "SHOULD" be just fine...
I do believe however that if you were not using the RS4 injectors, you would be having other fueling problems as well, which are now "covered" by the higher flow injectors.
P.S.Btw, have you ever checked your cam/follower for wear ?
 
#132 ·
Re: FV-QR (GolfRS)

You really are trying to make this more difficult than it is...
Quote, originally posted by GolfRS »

Injectors, and rail pressure are DIRECTLY related when it comes to fuel delivery.

Yes. We're on the same page as far as this statement goes.
Quote, originally posted by GolfRS »

Wait..are you just repeating what i wrote you above ?Or are you trying to make others understand better ?Weird...There must be an echo in here...


Every time i think i'm getting through to you, you turn around and surprise me so a little repetition to clarify the facts seems appropriate.

Quote, originally posted by GolfRS »

See this is what you are not getting...The stock Gti valve is good for 130 bar.NOTHING gets dumped until that limit is reached.That's why it is called a LIMITING VALVE.It LIMITS pressure to 130 bar.That means that since you are not even reaching 127 bar, your stock valve "SHOULD" be just fine...

See, this is what you are not getting. My stock valve (supposedly rated to 130bar as you mentioned) was NOT, i repeat NOT, making it to 130bar even though 130bar was being requested. Rail pressure was instead getting dumped at 127bar. This is where your best guesses on what is *supposed* to happen are trumped by my real world experience. Call it a defective valve or an acceptable tolerance level or whatever you want. Fact is it wasn't making it to the requested 130bar value. If your stock valve consistently is, i'm thrilled for you. Mine however was not. But with the RS4 valve it is now consistently, 100% of the time meeting or exeeding the requested 130bar value at the top end.
Quote, originally posted by GolfRS »
P.S.Btw, have you ever checked your cam/follower for wear ?
I have literally personally taken apart almost every (reasonable) part of my car over the time i have owned it. I'm starting to think you have a superiority complex going here on or are just accustomed to dealing with really incompetent people. The answer is yes. I'm very aware of what requesting more rail pressure means to other components.
 
#133 ·
Re: FV-QR (ndifadvokit)

Quote, originally posted by ndifadvokit »

Every time i think i'm getting through to you, you turn around and surprise me so a little repetition to clarify the facts seems appropriate.

Wait...What ??

Quote »
See, this is what you are not getting. My stock valve (supposedly rated to 130bar as you mentioned) was NOT, i repeat NOT, making it to 130bar even though 130bar was being requested. Rail pressure was instead getting dumped at 127bar. This is where your best guesses on what is *supposed* to happen are trumped by my real world experience. Call it a defective valve or an acceptable tolerance level or whatever you want. Fact is it wasn't making it to the requested 130bar value. If your stock valve consistently is, i'm thrilled for you. Mine however was not. But with the RS4 valve it is now consistently, 100% of the time meeting or exeeding the requested 130bar value at the top end.

Aahhh ok...Now i get it...You simply do not understand how the system works, and what this valve you changed ACTUALLY DOES...It is understandable then why you keep trying to convince me of something that is WRONG, simply because you understand it wrongly, and that doesn't make it right..That's where the problem lies...
Here it goes then, this is what you are confusing, and the reason why i already said above that people that have no knowledge of how the system works should not be installing parts in their car simply because they were TOLD TO, or encouraged to do so...
The valve that is present in the fuel rail in both the GTI and the RS4 is called a PRESSURE LIMITING VALVE (as i have already mentioned above) for a reason.It is NOT making or raising the pressure by ITSELF.And this is what you keep confusing, and the reason you have everything mixed up in your head.
According to the pressure the valve is RATED AT, it ALLOWS fuel to BLEED OFF the system/rail to avoid excessive pressure.BUT once again, it is not the one MAKING THAT PRESSURE.
To make it even more understandable to you (and others you have possibly confused) i'll give you an analogy.
Say you have a faucet and a hose that is attached to it, and that hose is capped at the other end (in our case non spraying injectors).If you turn on the faucet and leave it on (this represents the HPFP) pressure starts to build up in the hose.Now in this hose you have a pressure sensor (the sensor on the rail) that monitors the pressure in that hose.You want to keep the pressure stable in that hose (for many reasons, i won't get into this now) so you have a)the sensor for checking and b)A PRESSURE LIMITING VALVE (yes this is what we are talking about) acting as a "hole" in the hose, a hole that opens at 130 bar "HOSE PRESSURE".So when that sensor sees 130+ bar..pssssss fuel leaks out and pressure returns to sub 130 bar levels.Is that clear so far ?Do you get the DIFFERENCE with what you as saying and is in your mind ?
Now...what IF...you had a "bad" faucet (or a bad HPFP/cam/follower) which COULD NOT EVER MAKE 130 bar (in your case as you say 127).WHAT GOOD WOULD A 136 bar (RS4) or even 130 bar (GTI) make ??ZERO...NADA...And that is because due to the fault in the system PRESSURE WOULD NEVER HAVE TO BE RELEASED!!Does that make sense now ?Do you get it ?

Of course all of the above is a rather simplified analogy, simply because of the fact this is a dynamic system, with constant variations in fuel demand and delivery, but it serves well for you to get the big picture.I hope now you'll see where you were wrong and think the whole thing over....
Quote »
I have literally personally taken apart almost every (reasonable) part of my car over the time i have owned it. I'm starting to think you have a superiority complex going here on or are just accustomed to dealing with really incompetent people. The answer is yes. I'm very aware of what requesting more rail pressure means to other components.

I'm not even gonna address the personal comments, i think i've answered those by taking the time to explain to you what you have understood wrong, and that is enough....
I am hoping others will benefit from it too.
 
#135 ·
Re: (Uber-A3)

Quote, originally posted by Uber-A3 »
If you were never meeting the 129.9 requested how is this going to help do that? Your output was never enough that the gti valve was bleeding off, right?

There we go...
Now we are getting in the right path... http://****************.com/smile/emthup.gif
It becomes obvious though he didn't really know what the valve he installed does, but i am guessing that also goes for many other people that might be rushing to spend good money on this.
But i guess this is how a forum works...


Modified by GolfRS at 1:17 AM 4-14-2010


Modified by GolfRS at 1:17 AM 4-14-2010
 
#136 ·
Re: (GolfRS)

another thing I just thought of and maybe it was mentioned before.. How can this valve help the "flat feeling" at about 5k if rail pressure is nowhere near 130 bar? Not saying it doesn't but I am having a hard time wrapping my mind around how it could be beneficial.


Modified by Uber-A3 at 3:24 PM 4-13-2010
 
#137 ·
Re: (Uber-A3)

Quote, originally posted by Uber-A3 »
another thing I just thought of and maybe it was mentioned before.. How can this valve help the "flat feeling" at about 5k if rail pressure is nowhere near 130 bar? Not saying it doesn't but I am having a hard time wrapping my mind around how it could be beneficial.

Modified by Uber-A3 at 3:19 PM 4-13-2010

As i said, placebo effect...
It happens to all of us, with everything, starting from a simple valve going to an intake etc etc.
We are just wishing it to work so that the money and effort doesn't go to waste...
I can't begin to remember all the stuff i have in the garage that were.."supposed to work", but...didn't...
 
#138 ·
Re: FV-QR (GolfRS)

Seriously?? Have you read a single one of my responses thus far? You are regurgitating my own responses in order to pretend you're enlightening me. I have from the beginning been explaining to you that the valve in question here dumps pressure once it's rated limit is reached. This was stated from the beginning and the basis of all of my subsequent posts. Let's have some fun and do a quick review for those with reading comprehension problems...
Quote, originally posted by ndifadvokit »

Again, this valve won't magically add fuel where there wouldn't be fuel before. As you said, the stock fuel pump and RS4 injectors are more than able to keep up with what my software is requesting and what my humble turbo needs at the top. BUT, what isn't able to keep up is the stock fuel pressure valve as it would release rail pressure before the rail pressure could meet what was being requested (i.e. 129.99 bar).

Quote, originally posted by GolfRS »

The valve that is present in the fuel rail in both the GTI and the RS4 is called a PRESSURE LIMITING VALVE (as i have already mentioned above) for a reason.It is NOT making or raising the pressure by ITSELF.And this is what you keep confusing, and the reason you have everything mixed up in your head.
According to the pressure the valve is RATED AT, it ALLOWS fuel to BLEED OFF the system/rail to avoid excessive pressure.BUT once again, it is not the one MAKING THAT PRESSURE.

LMAO

Quote, originally posted by GolfRS »

Now...what IF...you had a "bad" faucet (or a bad HPFP/cam/follower) which COULD NOT EVER MAKE 130 bar (in your case as you say 127).WHAT GOOD WOULD A 136 bar (RS4) or even 130 bar (GTI) make ??ZERO...NADA...And that is because due to the fault in the system PRESSURE WOULD NEVER HAVE TO BE RELEASED!!Does that make sense now ?Do you get it ?

Quote, originally posted by ndifadvokit »

My stock valve (supposedly rated to 130bar as you mentioned) was NOT, i repeat NOT, making it to 130bar even though 130bar was being requested. Rail pressure was instead getting dumped at 127bar. This is where your best guesses on what is *supposed* to happen are trumped by my real world experience. Call it a defective valve or an acceptable tolerance level or whatever you want. Fact is it wasn't making it to the requested 130bar value. If your stock valve consistently is, i'm thrilled for you. Mine however was not. But with the RS4 valve it is now consistently, 100% of the time meeting or exeeding the requested 130bar value at the top end.

You keep thinking that because the valve is rated at 130bar it is only going to dump pressure when it gets to 130bar. WRONG. Again, i have shown that my valve was prematurely dumping at 127bar. I have also shown that with no other variables changed other than installing the RS4 valve that pressure is now correctly getting bled off after meeting the value being requested. Your theories and best guesses are less than my proven real world results.
GolfRS, you seem like a nice guy but you are proving to be too stubborn to learn. I am no longer going to try to teach you. My answers are recorded here for all to read. If you'd like to continue this conversation feel free to IM me. I challenge you to actually do some real world testing and then try to prove me wrong. I have data proving my point. You have nothing but your "theories". What needed to be said has been said and i'm done with replying to the same questions over and over again.
 
#139 ·
Re: (Uber-A3)

Quote, originally posted by Uber-A3 »
If you were never meeting the 129.9 requested how is this going to help do that? Your output was never enough that the gti valve was bleeding off, right?

You should first be asking WHY i wasn't meeting the 129.9bar request. My stock fuel regulator valve was dumping the pressure before it ever reached what it was supposed to. Just because the valve is rated to 130bar doesn't mean it actually is working at 130bar. Parts are not always perfect.
With nothing else changed other than installing the RS4 valve i am now able to easily meet and exceed 130bar. Not every once in a while, but 100% of the time. If you put two and two together it makes perfect sense.
 
#140 ·
Re: FV-QR (ndifadvokit)

Quote, originally posted by ndifadvokit »
Seriously?? Have you read a single one of my responses thus far? You are regurgitating my own responses in order to pretend you're enlightening me. I have from the beginning been explaining to you that the valve in question here dumps pressure once it's rated limit is reached. This was stated from the beginning and the basis of all of my subsequent posts. Let's have some fun and do a quick review for those with reading comprehension problems...
LMAO

You keep thinking that because the valve is rated at 130bar it is only going to dump pressure when it gets to 130bar. WRONG. Again, i have shown that my valve was prematurely dumping at 127bar. I have also shown that with no other variables changed other than installing the RS4 valve that pressure is now correctly getting bled off after meeting the value being requested. Your theories and best guesses are less than my proven real world results.
GolfRS, you seem like a nice guy but you are proving to be too stubborn to learn. I am no longer going to try to teach you. My answers are recorded here for all to read. If you'd like to continue this conversation feel free to IM me. I challenge you to actually do some real world testing and then try to prove me wrong. I have data proving my point. You have nothing but your "theories". What needed to be said has been said and i'm done with replying to the same questions over and over again.


Oh dear God....

It so seems you are not only unwilling to learn, but you are also an ASS, cause instead of acknowledging you have this thing all wrong and trying to UNDERSTAND, you keep repeating your lack of knowledge "trying" to make it look like you actually HAVE A CLUE....
So you have a GTI valve rated a 130 bar but bleeds off at 127 (now it bleeds, before it wasn't... "making that pressure") and you installed a 136 bar release valve that "magically works" (only you and God know what it does exactly), in a very strange way since according to your graphs you only reach ~134 bar of rail pressure for like a MILLISECOND and then pressure drops right off, RIGHT WHEN RAIL PRESSURE SHOULD BE AT ITS HIGHEST, and that is the rev limit...How amazing...

You know i've really tried to maintain my calm through all this, but i don't think this is working.
One thing i don't appreciate is people that "think they know" not only trying to force their wrong "knowledge", but also refuse to acknowledge they were wrong in the first place..And that because those are the people that spread misinformation, and cause all sorts of problems to people that simply don't know but are looking to learn.
So yeah man, say whatever you want, and shape it any way you want to.The fact is you have NO CLUE WHATSOEVER, and there actually might be something wrong with your car that you simply refuse to accept, and deal with.
As to who people want to believe and accept, i simply leave it to the readers.I'm pretty confident i've explained things in a way those that want to learn will see through all the garbage you've posted, and truly understand what (if anything) this valve "may" or "may not" do...
Best of luck with your car...You'll need it if you keep thinking like that... http://****************.com/smile/emthdown.gif
 
#141 ·
Re: FV-QR (GolfRS)

Quote, originally posted by GolfRS »

according to your graphs you only reach ~134 bar of rail pressure for like a MILLISECOND and then pressure drops right off, RIGHT WHEN RAIL PRESSURE SHOULD BE AT ITS HIGHEST, and that is the rev limit...How amazing...

Learn to read.
Quote, originally posted by Uber-A3 »

why the big drop off in rail pressure after the rs4, the one where is is way above requested and them just drops?

Quote, originally posted by ndifadvokit »

I let off the throttle. Keep in mind the sample rate is pretty bad and the graph is merely connecting one dot to another with a line. So it looks like it's dipping down however, there're only two data points recorded which are 134 bar and then straight to 124 bar. I probably could've cut that last point out but i used it in the other graphs so i left it in there. My other two runs from the same session stay at 129 & 130 bar
 
#142 ·
Re: FV-QR (ndifadvokit)

Quote, originally posted by ndifadvokit »

Learn to read.

Yeah man, that right there proves you don't have a clue what the f*ck you are talking about...
When you..."lift off the throttle" as you say, your requested boost doesn't stay at 19 psi, (nor does you actual at 16 psi for that matter), your lambda value should have been offset and not stable at 0.8, and your requested rail pressure should have also fell along with your actual, cause you don't keep 130 bar requested rail pressure for 500 rpm...OFF THE THROTTLE.
So next time, cut the bull****, get some more knowledge and a few more posts under your belt, and THEN come back and tell me I CAN'T READ.
F*IN NOOB...
 
#143 ·
Re: FV-QR (GolfRS)

Quote, originally posted by GolfRS »

When you..."lift off the throttle" as you say, your requested boost doesn't stay at 19 psi, (nor does you actual at 16 psi for that matter), your lambda value should have been offset and not stable at 0.8, and your requested rail pressure should have also fell along with your actual, cause you don't keep 130 bar requested rail pressure for 500 rpm...OFF THE THROTTLE.
So next time, cut the bull****, get some more knowledge and a few more posts under your belt, and THEN come back and tell me I CAN'T READ.

Quote, originally posted by LEWXCORE »

when you let off throttle and stay in gear fuel delivery cuts off completely

Quote, originally posted by ndifadvokit »

only if you let off the throttle completely. Accelerator pedal position goes from 99.6% to 73.3%.

Maybe a different question but same answer.
 
#144 ·
Re: (ndifadvokit)

Quote, originally posted by ndifadvokit »

You should first be asking WHY i wasn't meeting the 129.9bar request. My stock fuel regulator valve was dumping the pressure before it ever reached what it was supposed to. Just because the valve is rated to 130bar doesn't mean it actually is working at 130bar. Parts are not always perfect.
With nothing else changed other than installing the RS4 valve i am now able to easily meet and exceed 130bar. Not every once in a while, but 100% of the time. If you put two and two together it makes perfect sense.

then your stock valve was bad and replacing with the gti valve would have netted the same results. Not by going over 129.9 but up to it at least. Unless the stock valve really isn't rated at the claimed 130 bar.
 
#145 ·
Re: FV-QR (ndifadvokit)

Quote, originally posted by ndifadvokit »

Maybe a different question but same answer.

Quote »
only if you let off the throttle completely. Accelerator pedal position goes from 99.6% to 73.3%.

FFS stop writing crap.
Have you tried lifting off the throttle even 10% while in full boost ?
Do you have ANY IDEA what happens to your boost ?
You can't maintain a smooth boost line ant 16 psi running PART THROTTLE...

You are full of it man.
Please stop it.You are making an ass of yourself.
 
#147 ·
Re: (Uber-A3)

Quote, originally posted by Uber-A3 »

then your stock valve was bad and replacing with the gti valve would have netted the same results. Not by going over 129.9 but up to it at least. Unless the stock valve really isn't rated at the claimed 130 bar.

right. but i had the choice of replacing my stock valve with another stock one that might or might not have the same problem as my first one or go with the RS4 valve which probably costs the same and is rated higher. What would you choose?
 
#148 ·
Re: (Uber-A3)

Quote, originally posted by Uber-A3 »

then your stock valve was bad and replacing with the gti valve would have netted the same results. Not by going over 129.9 but up to it at least. Unless the stock valve really isn't rated at the claimed 130 bar.

Why are you trying to have a logical debate with this person ?
It is obvious he is talking out of his "other hole"...
Don't even try to reason with him, he doesn't have a clue FFS !!!
 
#150 ·
Re: FV-QR (GolfRS)

Quote, originally posted by GolfRS »

FFS stop writing crap.
Have you tried lifting off the throttle even 10% while in full boost ?
Do you have ANY IDEA what happens to your boost ?
You can't maintain a smooth boost line ant 16 psi running PART THROTTLE...

You are full of it man.
Please stop it.You are making an ass of yourself.


If you honestly think i am lying you are more than welcome to take this offline with me on IMs. Run the same logs using the same poor sample rate i'm stuck with and then report back.
 
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