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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Fueling Resistors -- What Do They Do? Using This Data for Upgraded Turbos or Nitrous



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      05-13-2010, 06:08 PM   #1
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Fueling Resistors -- What Do They Do? Using This Data for Upgraded Turbos or Nitrous

Let me start by saying this is not going to be another one of my long winded reviews. LOL! My hope is this will turn into a valuable discussion, using real data, to discuss the fueling capabilities of the stock fuel system. All the testing you will see was done on a JB3 2.0 running Map 7 (~14 psi) and approximately 670 ml/min of water/methanol (~70/30). All the data was retrieved with an FJO wideband using high speed datalogging. Off nitrous, my car has an increase of about 150 rwhp over stock on a Mustang Dyno or about 165 rwhp on a dynojet. My car makes about 406 rwhp on a Mustang Dyno and about 445 rwhp on dynojet without nitrous.

Each tune has fueling resistors that determine how much additional fuel the tune can ask for. Why does this matter? Well on lower boost it is really not that important, but as you go to higher boost, race gas settings, nitrous, and ultimately upgraded turbos it will matter a whole lot. Through testing I am finding out what different fueling resistors will do. I want to present some of the data now for the community to look over.

5.5k Ohm Resistors



3.3k Ohm Resistors



2.2k Ohm Resistors



1.0k Ohm Resistors



Finally, a comparison between the 2.2k ohm resistors and 1k ohm resistors.





So what does that mean? Well you can see the lower the resistance on the fueling resistor the richer the car will run when the tune is asking for 100% fuel. You can also see that with the 5.5k ohm fueling resistor the car is aiming for an A/F ratio of 14:1 at 3000 rpms when asking for 100% fuel increase. With the 1.0k ohm fueling resistor the car is aiming for an A/F ratio of 12.5:1 at 3000 rpms when asking for 100% fuel increase. Up top with the 5.5k ohm fueling resistors the car is aiming for an A/F ratio of 12.5:1 at 6000 rpms when asking for 100% fuel increase. Up top with the 1k ohm fueling resistor the car is asking for 10.2:1 A/F ratio at 6000 rpms when the tune is asking for 100% fuel increase.

Those are the facts. Now why in the world would you want a rich A/F of 10.2:1 up top? You would not, but having the ability to richen up the mid rpms is tremendously important for upgraded turbos and nitrous. I am not sure how each tune works, but the JB3 can very easily swap fueling resistors on the board in about 20 minutes. It is easy work and clearly Terry was thinking of the future when designing the board this way. What this means is Terry can design an alternative set of maps for the 1.0k ohm resistors and allow us to run a much richer mid rpm and just ask for less than 100% fuel up top to keep the 12.0:1 - 12.5:1 ratios. On a low boost car, the DI clearly can handle the 14.0:1 A/F ratio without knock, but on nitrous or upgraded turbos that is just too lean for my taste. Terry is in the process of making the A/F adjustments for 1.0k ohm fueling resistors as I suspect a lot of people will be changing over with the introduction of nitrous and turbo upgrades.

One other thing that is very important to note is that this will give us REAL insight into the capacity of the N54 fueling system. Clearly at appoximately 445 rwhp on pump, the car has a lot of fuel left of it would not show such a huge difference between the 2.2k ohm resistor and 1.0k ohm resistor. I will be testing more and more nitrous to find out when the car cannot maintain A/F ratio and we will find the real limits of this fuel system rather than speculating. I was not going to run more nitrous until we were able to sufficiently richen up the mid rpms, but now with the 1k ohm resistors we have it where it needs to be. Once Terry leans the top from 10.2:1 up to around 11.5:1 then my testing with more nitrous will begin. Thus far I have made 487 rwhp on a Mustang Dyno with a 35 shot (.031 jet) or 526 rwhp dynojet equivelant on pump gas. I hope to make a little more shortly. I will hopefully test the limits of the stock fuel system on pump, then see what power we can make on MS109.

I have a lot of other thoughts, but I wanted to open this discussion. I have monitored fuel pressure during the testing as well, so I will now be able to comment with direct knowledge on how fuel pressure changes with increasing fuel demands. Anyone that wants to go this route on the JB3 (once Terry finishes the tune for the 1.0k ohm resistors) can simply change out the fueling resistors. I think this is going to be the future especially for the guys upgrading turbos and using nitrous. This will give you a whole lot more headroom and a lot more safety especially considering the N54 is a DI motor in my opinion.
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      05-13-2010, 06:11 PM   #2
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      05-13-2010, 06:27 PM   #3
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One other thing that is very important to note is that this will give us REAL insight into the capacity of the N54 fueling system. Clearly at appoximately 445 rwhp on pump, the car has a lot of fuel left of it would not show such a huge difference between the 2.2k ohm resistor and 1.0k ohm resistor. I will be testing more and more nitrous to find out when the car cannot maintain A/F ratio and we will find the real limits of this fuel system rather than speculating.
Good to know re: fueling system.

As always, we're grateful for your contribution to the community. Keep up the good work Former_Boosted_IS!
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      05-13-2010, 06:47 PM   #4
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I wonder what Shiv has to say about this and what the Procede can do in respect to running nitrous with the A/F...I am glad Terry has been working with you...Looking forward to seeing what your car can do with even a bigger jet of .31!!! Your a maniac
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      05-13-2010, 07:03 PM   #5
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Originally Posted by cn555ic View Post
I wonder what Shiv has to say about this and what the Procede can do in respect to running nitrous with the A/F...I am glad Terry has been working with you...Looking forward to seeing what your car can do with even a bigger jet of .31!!! Your a maniac
+1

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      05-13-2010, 07:23 PM   #6
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Keep in mind that there is only so much fuel available. Running map 7 will nto produce numbers where you will be running out of fuel. I have personally made a fpred turbo request so much fuel that the fuel pressure was not able to keep up. You will soon run into this problem. Good luck and keep it safe, I hope you have a way to accuratly log direct fuel pressure, not meaningless numbers. If you're wondering this was the AMS car
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      05-14-2010, 05:57 AM   #7
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Good to know re: fueling system.

As always, we're grateful for your contribution to the community. Keep up the good work Former_Boosted_IS!
We should know a lot more as I move forward.

On thing to note is that during peak torque on the stock fueling resistors on both tunes it appears the car can only target about a 14.0:1 A/F ratio. Those that are running aggressive setups really need to change those fueling resistors bad. I will be testing more now that I have fattened up the peak torque area and I will move forward.
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      05-14-2010, 05:59 AM   #8
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Originally Posted by cn555ic View Post
I wonder what Shiv has to say about this and what the Procede can do in respect to running nitrous with the A/F...I am glad Terry has been working with you...Looking forward to seeing what your car can do with even a bigger jet of .31!!! Your a maniac
Just an enthusiast like the rest.

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+1

keep pushin' FBI!!
Thanks. I will let you guys know what I come up with.
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      05-14-2010, 06:07 AM   #9
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Keep in mind that there is only so much fuel available. Running map 7 will nto produce numbers where you will be running out of fuel. I have personally made a fpred turbo request so much fuel that the fuel pressure was not able to keep up. You will soon run into this problem. Good luck and keep it safe, I hope you have a way to accuratly log direct fuel pressure, not meaningless numbers. If you're wondering this was the AMS car
I do have a way log fuel pressure accurately and have been doing so. When I put down 487 rwhp on the Mustang Dyno (or 526 Dynojet equivelant), I logged a FP of about 760-780. I still haven't got to the point even with nitrous that the car cannot hit the target A/F ratio. I am not implying map 7 will tax the fuel system, but nitrous and 16 psi of boost eventually will. I felt it was a necessary precaution to rich up peak torque A/F from 14.0:1 up to 12.5:1 before pushing forward. Now that I have done that I will lean out the upper rpms to about 11.2-11.5:1 and move forward.

On top of this, I will be making some turbo changes that should really help me to put down some nice numbers.
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      05-14-2010, 06:12 AM   #10
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Shiv hasn't chimed in, so I would think Procede is capable of this...He is changing the Procede to read the Lamba front 02 sensors so it should be more accurate, but from what I have logged using the rear sensors, the A/F in the upper RPM bands have been consistently near or under 12:1

I know Terry gives great support and the product is awesome, question is how come you never tried the V4 especially since you are usually on top of the cutting edge stuff? I just find it really odd that you didn't even try it out???
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      05-14-2010, 06:55 AM   #11
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Shiv hasn't chimed in, so I would think Procede is capable of this...He is changing the Procede to read the Lamba front 02 sensors so it should be more accurate, but from what I have logged using the rear sensors, the A/F in the upper RPM bands have been consistently near or under 12:1

I know Terry gives great support and the product is awesome, question is how come you never tried the V4 especially since you are usually on top of the cutting edge stuff? I just find it really odd that you didn't even try it out???
Does anyone know what the stock fueling resistors are on the Procede? If they are around 5k ohm, then that limits how much you can bias the O2 sensors. That limits how much additional fuel you can request period. Up top is not where the issue lies because the 5k ohm resistors can more than bias the O2 sensors enough to get a safe 12.0 - 12.5:1 AFR, but at around 4k rpms where the car is at peak torque you are heavily limited with 5k ohm resistors. I suspect you are running near 14.0:1 at peak torque and I am not even remotely comfortable with that to be honest. Next, which sensor you log should have no effect on the ability of the tune to add fuel, but the fueling resistor does.

Honestly, I have never said a negative thing about Shiv or the Procede and never will. He seems to have a great product and a fantastic customer base. Like everyone else on the forums I considered both tunes and found the JB3 to meet my personal needs best. Terry has been absolutely incredibly flexible in working with me to adapt his tune to meet my needs. He emails me with 10 minutes of sending him an email whether it is during the week or on the weekend. I just feel like he has earned my business and I am lucky to have him as my tuner. Like every single product I review, this is just my opinion and I have never pushed it on anyone.
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      05-14-2010, 07:01 AM   #12
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Does anyone know what the stock fueling resistors are on the Procede? If they are around 5k ohm, then that limits how much you can bias the O2 sensors. That limits how much additional fuel you can request period. Up top is not where the issue lies because the 5k ohm resistors can more than bias the O2 sensors enough to get a safe 12.0 - 12.5:1 AFR, but at around 4k rpms where the car is at peak torque you are heavily limited with 5k ohm resistors. I suspect you are running near 14.0:1 at peak torque and I am not even remotely comfortable with that to be honest. Next, which sensor you log should have no effect on the ability of the tune to add fuel, but the fueling resistor does.

Honestly, I have never said a negative thing about Shiv or the Procede and never will. He seems to have a great product and a fantastic customer base. Like everyone else on the forums I considered both tunes and found the JB3 to meet my personal needs best. Terry has been absolutely incredibly flexible in working with me to adapt his tune to meet my needs. He emails me with 10 minutes of sending him an email whether it is during the week or on the weekend. I just feel like he has earned my business and I am lucky to have him as my tuner. Like every single product I review, this is just my opinion and I have never pushed it on anyone.
Cool...I was just curious! As for the fueling and the resistors, Shiv will have to answer that question, but like you I have full confidence in the tune and what he suggests, so with that I will have to wait to see how he responds!


BTW...I just ordered the purge kit and the bottle heater, and will be completing the hardware part of the install!! I found a nice location for my single tube purge....right smack in the middle of the cabin filter! Thanks again for you DIY, it made it really easy to refer back to and give me the confidence to do it myself!
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      05-14-2010, 07:03 AM   #13
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Cool...I was just curious! As for the fueling and the resistors, Shiv will have to answer that question, but like you I have full confidence in the tune and what he suggests, so with that I will have to wait to see how he responds!


BTW...I just ordered the purge kit and the bottle heater, and will be completing the hardware part of the install!! I found a nice location for my single tube purge....right smack in the middle of the cabin filter! Thanks again for you DIY, it made it really easy to refer back to and give me the confidence to do it myself!
Nice! I can't wait to see what it looks like purging. Purging just looks so cool!

The bottle heater should be very easy to install too. If you have any questions along the line drop me a pm or IM.
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      05-14-2010, 07:31 AM   #14
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I do have a way log fuel pressure accurately and have been doing so. When I put down 487 rwhp on the Mustang Dyno (or 526 Dynojet equivelant), I logged a FP of about 760-780. I still haven't got to the point even with nitrous that the car cannot hit the target A/F ratio. I am not implying map 7 will tax the fuel system, but nitrous and 16 psi of boost eventually will. I felt it was a necessary precaution to rich up peak torque A/F from 14.0:1 up to 12.5:1 before pushing forward. Now that I have done that I will lean out the upper rpms to about 11.2-11.5:1 and move forward.

On top of this, I will be making some turbo changes that should really help me to put down some nice numbers.
760-780psi? that CANNOT be correct. What are you using to log fuel pressure? You should over 3k down low dropping to 1800 or so up top. What you are logging might be what the piggy feeds the ecu. (false signal)
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      05-14-2010, 07:38 AM   #15
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760-780psi? that CANNOT be correct. What are you using to log fuel pressure? You should over 3k down low dropping to 1800 or so up top.
Fuel pressure should be dropping at high rpms? That doesn't sound logical, but I will admit I am not the expert here. I am using the JB3 to log the fuel pressure and I have been simply looking at it in Excel. I wonder if there is a scale that is applied to it?

Maybe I need to learn more about pressures from the HPFP?
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      05-14-2010, 07:46 AM   #16
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      05-14-2010, 07:48 AM   #17
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Fuel pressure should be dropping at high rpms? That doesn't sound logical, but I will admit I am not the expert here. I am using the JB3 to log the fuel pressure and I have been simply looking at it in Excel. I wonder if there is a scale that is applied to it?

Maybe I need to learn more about pressures from the HPFP?
I've done extensive work with cpe regarding fuel pressure changes/monitoring/pump development on my previous DI car and some on this car. If my memory severs me right stock fuel pressure hits 2200-2400psi down low and falls down to 1600ish on a bone stock car. Yes the fuel pressure drops as rpms rise. Once I get home Ill jump on my tuning lap top to see if i can post some logs for you, but def ask terry about the scaling he is using because those numbers are not accurate.

There is also two ways to request more fuel which both alter fuel pressure. The standback alters the o2 signal to request more fuel and it also alters the actual fuel pressure. I am not sure how the jb3 does it, but both solution raise pressure as expected, however in a different way.

Another thing to think about, being that this is a DI motor which mean pressure is directly injected into the cylinder, af ratios gathered from widebands are not exactly accurate as you request more fuel. Think of it this way, the time frame that an injector has to fire is extremely small and limited, meaning you can only inject usable fuel during that period. If that window closes the valves being to open/close and you are still injecting fuel because your targets request this, the excess fuel that gets injected simply gets blow out the exhaust and fools your wideband into thinking you are running rich.
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      05-14-2010, 07:54 AM   #18
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I've done extensive work with cpe regarding fuel pressure changes/monitoring/pump development on my previous DI car and some on this car. If my memory severs me right stock fuel pressure hits 2200-2400psi down low and falls down to 1600ish on a bone stock car. Yes the fuel pressure drops as rpms rise. Once I get home Ill jump on my tuning lap top to see if i can post some logs for you, but def ask terry about the scaling he is using because those numbers are not accurate.

There is also two ways to request more fuel which both alter fuel pressure. The standback alters the o2 signal to request more fuel and it also alters the actual fuel pressure. I am not sure how the jb3 does it, but both solution raise pressure as expected, however in a different way.

Another thing to think about, being that this is a DI motor which mean pressure is directly injected into the cylinder, af ratios gathered from widebands are not exactly accurate as you request more fuel. Think of it this way, the time frame that an injector has to fire is extremely small and limited, meaning you can only inject usable fuel during that period. If that window closes the valves being to open/close and you are still injecting fuel because your targets request this, the excess fuel that gets injected simply gets blow out the exhaust and fools your wideband into thinking you are running rich.
If you are saying that the widebands are not accurate then how in the world are you measuring AFRs? I have been able to replicate these results over and over and over. If there were inconsistencies it would have shown up over the large sample I have.
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      05-14-2010, 08:00 AM   #19
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If you are saying that the widebands are not accurate then how in the world are you measuring AFRs? I have been able to replicate these results over and over and over. If there were inconsistencies it would have shown up over the large sample I have.
It won't show inconsistencies. Think of it this way. On a port injection car, as you know, you can max duty cycles and just spray 100 percent of the time, stroke means nothing as the fuel goes through the intake manifold into the head to cause combustion right? On a DI car, you have a limited time that fuel will get ignited, once combustion in that cylinder completes the rest of the fuel you are spraying on the down stroke, gets blow out the valves which fools you o2 sensors. As far as how to measure a/f ratios, once you starting pushing limits, which you are, you simply can't be sure wtf is going on. Welcome to the wonderful world of direct injection. If you notice, any vw di car that makes huge power, resorts to a di/pi set up for this very reason. You can dump all the fuel you want if pressure doesnt drop, it doesnt mean that this fuel is used for combustion though. I've seen a 70mm ms3 dyno 320who at 27psi PISSING black smoke out the exhaust, af in the 9s. However the car made no power and was about 100-150whp off because it didn't have enough fuel despite the af readings showing stupid rich. I am at work right and this is sort of hard to explain, but ill go more in dept over the weekend if you need more info to grasp the lovely concept of DI.

I am not sure when this window gets maxed out, but the next logical step is to alter the "window" of when injectors begin to fire. This can done with flashes only. But like I said, you still made your high 400whp, so you are not there yet, but Im betting its close.

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      05-14-2010, 08:07 AM   #20
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It won't show inconsistencies. Think of it this way. On a port injection car, as you know, you can max duty cycles and just spray 100 percent of the time, stroke means nothing as the fuel goes through the intake manifold into the head to cause combustion right? On a DI car, you have a limited time that fuel will get ignited, once combustion in that cylinder completes the rest of the fuel you are spraying on the down stroke, gets blow out the valves which fools you o2 sensors. As far as how to measure a/f ratios, once you starting pushing limits, which you are, you simply can't be sure wtf is going on. Welcome to the wonderful world of direct injection. If you notice, any vw di car that makes huge power, resorts to a di/pi set up for this very reason. You can dump all the fuel you want if pressure doesnt drop, it doesnt mean that this fuel is used for combustion though. I've seen a 70mm ms3 dyno 320who at 27psi PISSING black smoke out the exhaust, af in the 9s. However the car made no power and was about 100-150whp off because it didn't have enough fuel despite the af readings showing stupid rich. I am at work right and this is sort of hard to explain, but ill go more in dept over the weekend if you need more info to grasp the lovely concept of DI.
The thing is my car is continuing to make more horsepower. I have tested this on a dyno and I am not running stupid fat. I am sure all of the higher hp applications will over over to port injection as well, but that is not a solution now. Regardless the point of this discussion still was that we can begin to test the limits of the fuel system. At some point we should see either major inconsistencies or the A/F going leaner and leaner as we reach the limits of the fuel system.

Quote:
I am not sure when this window gets maxed out, but the next logical step is to alter the "window" of when injectors begin to fire. This can done with flashes only. But like I said, you still made your high 400whp, so you are not there yet, but Im betting its close.
We should be able to find that window regardless.
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      05-14-2010, 08:10 AM   #21
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Originally Posted by Former_Boosted_IS View Post
The thing is my car is continuing to make more horsepower. I have tested this on a dyno and I am not running stupid fat. I am sure all of the higher hp applications will over over to port injection as well, but that is not a solution now. Regardless the point of this discussion still was that we can begin to test the limits of the fuel system. At some point we should see either major inconsistencies or the A/F going leaner and leaner as we reach the limits of the fuel system.
It wont show inconsistencies though, It will be consistently rich lol, however it won't be accurate. Like I said in my edited post, you are not there yet being that you are still making power, however you should be close to maxing out the injector "time frame" cause as stated, the window useable fuel gets injected on a DI motor is alot smaller than that of a PI car. But first things is first, get accurate fp measurements from terry's scaling factor.
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      05-14-2010, 08:14 AM   #22
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a cool little video of how this works

keep in mind as rpms rise, this window technically get smaller and smaller right? Think about the time frames needed at 6000 rpm and you'll see how the fuel will begin to get blown out the exhaust and will not be used for combustion
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