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Fueling PWM System

2261 Views 44 Replies 5 Participants Last post by  kittyboy, 
kittyboy
Request tuner feedback. My advance thank you...

At 5100rpm, 15.8lbs boost, 65psi fuel, 68% injector duty, 51lbs injector flow, 100% pump DC.

Stock PMW system, 1050x injectors (characterized), DW300c pumps w/ 80-90prv, boost modulation cut disabled. 92 pump boosted with 10% toluene.

My calculations take into account a 5psi drop in rail fuel pressure at WOT.

Based on the above, pressure delta minus 5psi rail pressure drop, I figure to increase the injector duty cycle up to 80% by adding 20% to the flow rates in my Flow vs Pressure Delta table. I do not want to exceed 80% injector duty cycle at any time.

I've observed the Flow vs Press Delta table is very accurate at WOT. My goal is to maintain a steady 1 bar delta at WOT at any given time.

I modified the FPCM fuel pump percentage in the OL Fuel Press DC table to ramp the pumps 100% at 131lbs Instantaneous fuel pressure and above. I set Regulation Pressure to 65psi max at 131lbs Instantaneous and above for voltages between 12v-18v. Added 20% to the Flow Rate tables (Engine and FPCM) from 41.8 Pressure Delta to get the 80% at 65psi fuel pressure I hope to achieve.


Side note:
Trial/error/observation, with a 80-90prv installed in a stock PWM system, fuel pressures jump and remain at 'pump' unfriendly elevated pressure levels during normal (non-boost) driving conditions. I have overcome this by setting all max fuel pressure tables to 50psi, both in the Engine and FPCM. Note, despite the 50psi max set values, these are superseded above 5000rpm.

My observation currently leads me to believe that the Flow/Press table in the FPCM does little or nothing, limited to 63.5lbs compared to the Engine Flow/Press table 127lbs. The upper values will never be realized any how.

My goal is to remain at a constant 1 bar at WOT, of course after calculating for the delta, maximize injector flow and duty cycle to 80% potential at a 100% pump flow.

DW does not recommend exceeding 16v on the 300c pumps or running high pressure needlessly for extended periods. Don't think the V will ever see 16v, but I have never actually hooked-up a meter?

Again, thank you for feedback...

I also want to add the following while on the subject for those less experienced with fueling as a confidence building side note, and wanting to remain on pump gas.

I have learned based on personal experience, the stock PMW system using pump gas (92 minimum) is an outstanding OEM setup for those with plans not exceeding the 800hp range at the crank. This does require installing larger capacity pumps, injectors, and PRV. Very important to properly tune the Engine and FPCM afterwards. I personally run a bit rich at WOT to accommodate the rear #7 and #8 cylinders. The only real pain is accessing the fuel pump assembly, need to be extremely careful not to damage fuel lines when cutting away the sheet metal, clearance is around 0.125"-0.250"
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random84
Without really going into your details, my limited experience is that any changes to the FPCM take several driving cycles to "average" down, likely due to non-modifiable trims or other tables we just don't have access to.

Also, think in terms of percent change to any tables, as the absolute values never seemed to match up for me. Again, likely due to the same reasons (non-modifiable or unseen tables).

YMMV

I believe the Z06 PRV is 67-69psi, that might be an easy work around. I currently command 45psi rail pressure and after several sessions of tuning the pump duty cycle have it pretty close to desired rail pressures of 55 and 70 psi (45psi low flow, 55 normal and 70 high). Given the amount of time you're on high flow, I am not worried about pump life.

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kittyboy
random84 said:
Without really going into your details, my limited experience is that any changes to the FPCM take several driving cycles to "average" down, likely due to non-modifiable trims or other tables we just don't have access to.

Also, think in terms of percent change to any tables, as the absolute values never seemed to match up for me. Again, likely due to the same reasons (non-modifiable or unseen tables).

YMMV

I believe the Z06 PRV is 67-69psi, that might be an easy work around. I currently command 45psi rail pressure and after several sessions of tuning the pump duty cycle have it pretty close to desired rail pressures of 55 and 70 psi (45psi low flow, 55 normal and 70 high). Given the amount of time you're on high flow, I am not worried about pump life.

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Yeah, it's the scientific method, don't know if it's even a concept learned in school any longer. But at least with HP tuners and pillar of gauges I can log without fear. See how things go. The weather is cooling down now, so my advanced tuning might need to get put on ice for a while unfortunately.
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kittyboy
I also wanted to add that I no longer concern myself with the Mode Condition settings, I am either in normal or high. The advance fuel estimate is set at a high level.
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kittyboy
random84 said:
Without really going into your details, my limited experience is that any changes to the FPCM take several driving cycles to "average" down, likely due to non-modifiable trims or other tables we just don't have access to.

Also, think in terms of percent change to any tables, as the absolute values never seemed to match up for me. Again, likely due to the same reasons (non-modifiable or unseen tables).

YMMV

I believe the Z06 PRV is 67-69psi, that might be an easy work around. I currently command 45psi rail pressure and after several sessions of tuning the pump duty cycle have it pretty close to desired rail pressures of 55 and 70 psi (45psi low flow, 55 normal and 70 high). Given the amount of time you're on high flow, I am not worried about pump life.

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The pump life issue was primarily aimed at those that run constant high pressures due to after market pumps and PRV installed and not tuned properly.
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07GTS
do not adjust the injector data to add for duty, the injector data is set so u get the proper injection under all delta conditions to suit each injector set, adjusting those tables then puts the rest of the tune, torque and air model in error, if u want more duty then lower the actual pressure to the injectors so then the delta will increase duty to compensate
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kittyboy
07GTS said:
do not adjust the injector data to add for duty, the injector data is set so u get the proper injection under all delta conditions to suit each injector set, adjusting those tables then puts the rest of the tune, torque and air model in error, if u want more duty then lower the actual pressure to the injectors so then the delta will increase duty to compensate
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What effect will increasing the flow rate vs pressure have on the duty cycle? My thought process is I should be able to increase the flow rate and reduce the duty without having to increase the fuel pressure dramatically. At the current delta I am only in the 50s for flow? ty

Added:
I understand charges will have an effect in other areas that will need adjustment. Guess what I am hung-up on, trying to better clarify, understand, is it possible to increase the flow of an injector without increasing the fuel pressure? It may not be possible? Maybe a larger injector is needed for increasing the flow at lower pressure?
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07GTS
the injectors u have and the data u get for them are concrete, that is how the operation of those injectors work so when u command a 2ms PW then that is what u get for all scenarios, unless u change the commanded fuel to the engine the duty wont change, increasing the IFR will tell the ecu that the injectors are larger so the PW will be smaller then as the PW is smaller u will be leaner so have to increase the maf/vve tables to get fueling back to correct (which is now in error of accuracy and duty is still the same)

if u want to use more duty only way is lower fuel pressure that way the injectors act smaller and the IFR delta says they are flowing less because they actually are so then the PW increases, but this time maf/vve are still correct and it was a fuel pressure change, each injectors flow is set per the testing at 43.5psi (300kpa) or 58psi (400kpa) from manufacture, only way to change it is running them at a higher or lower fuel pressure, or yes u will need larger injectors to run at lower pressure which also lowers your duty but u have more head room in the top end if want to make more power in future, if ur at 68% duty thats ok if u can lower fuel pressure to 58psi that will increase it to maby 75% duty and that will leave a bit for winter as well will go a little higher with cooler dense air, hope that all makes sense and helps
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Lt1z
I would agree with leaving your injector data alone and controlling pressure however my experience with the products you are using has not been great in customers cars that came in equipped that way. Not a setup I would suggest or sell as a solution to people.
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kittyboy
07GTS said:
the injectors u have and the data u get for them are concrete, that is how the operation of those injectors work so when u command a 2ms PW then that is what u get for all scenarios, unless u change the commanded fuel to the engine the duty wont change, increasing the IFR will tell the ecu that the injectors are larger so the PW will be smaller then as the PW is smaller u will be leaner so have to increase the maf/vve tables to get fueling back to correct (which is now in error of accuracy and duty is still the same)

if u want to use more duty only way is lower fuel pressure that way the injectors act smaller and the IFR delta says they are flowing less because they actually are so then the PW increases, but this time maf/vve are still correct and it was a fuel pressure change, each injectors flow is set per the testing at 43.5psi (300kpa) or 58psi (400kpa) from manufacture, only way to change it is running them at a higher or lower fuel pressure, or yes u will need larger injectors to run at lower pressure which also lowers your duty but u have more head room in the top end if want to make more power in future, if ur at 68% duty thats ok if u can lower fuel pressure to 58psi that will increase it to maby 75% duty and that will leave a bit for winter as well will go a little higher with cooler dense air, hope that all makes sense and helps
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Thanks for the feedback, I have steady fuel pressure at WOT without any drop, just thought there might be some method to increase the flow to maximize injector potential without increasing fuel pressure. I'll follow your advice and keep the flow tables characterized per the ID spreadsheet values. I have enough 'headroom' to make more power with my current configuration, no worry. Thanks again...
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kittyboy
Lt1z said:
I would agree with leaving your injector data alone and controlling pressure however my experience with the products you are using has not been great in customers cars that came in equipped that way. Not a setup I would suggest or sell as a solution to people.
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Thanks for the feedback, I know you and 07GTS have way more experience on this subject than I do. What products do you usually suggest for 800hp-ish power range? I have been pleased so far with the ID and DW setup. I realize I'm at the point on pump gas where I've reached a safe limit.
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Lt1z
kittyboy said:
Thanks for the feedback, I know you and 07GTS have way more experience on this subject than I do. What products do you usually suggest for 800hp-ish power range? I have been pleased so far with the ID and DW setup. I realize I'm at the point on pump gas where I've reached a safe limit.
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Over 800whp I generally have some sort of aux pump or return system with ID1300s if running E85. On pump gas your fueling requirements will be less and 1050s would suffice.
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kittyboy
Lt1z said:
Over 800whp I generally have some sort of aux pump or return system with ID1300s if running E85. On pump gas your fueling requirements will be less and 1050s would suffice.
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That's good news!

I've also been tuning my SD recently, up to this point running MAF. With the SD enabled the lower end performance and drivability has noticeably improved. It's a real learning curve working with the VVE table making changes. Originally I was considering installing the 2 bar patch, but decided at this time to go with the VVE table scaled at 2 bar, not really in the 3 bar performance zone at this time. Still experiencing a small bit of cold morning initial start-up hesitation for the first 15 seconds?
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Lt1z
kittyboy said:
That's good news!

I've also been tuning my SD recently, up to this point running MAF. With the SD enabled the lower end performance and drivability has noticeably improved. It's a real learning curve working with the VVE table making changes. Originally I was considering installing the 2 bar patch, but decided at this time to go with the VVE table scaled at 2 bar, not really in the 3 bar performance zone at this time. Still experiencing a small bit of cold morning initial start-up hesitation for the first 15 seconds?
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I generally do not change the OS but do run a blended model. Only occasionally do I do a full SD tune on these cars, most related to if the intake has shitty maf transfer and causes drivability issues.
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kittyboy
Lt1z said:
I generally do not change the OS but do run a blended model. Only occasionally do I do a full SD tune on these cars, most related to if the intake has shitty maf transfer and causes drivability issues.
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That's interesting. It took me a while to get the MAF and Volumetric Airflow to mach with the Dynamic, but I managed a good balance up to the stock 4000rpm disable point. Guess anything after that doesn't matter?
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Lt1z
kittyboy said:
That's interesting. It took me a while to get the MAF and Volumetric Airflow to mach with the Dynamic, but I managed a good balance up to the stock 4000rpm disable point. Guess anything after that doesn't matter?
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That point does not need to stay at 4000
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kittyboy
Lt1z said:
That point does not need to stay at 4000
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I figured, but really don't now why it's set at that level in the first place?
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07GTS
personally i like the 2 bar OS (actually 2.5bar) as u get the BE table so u can adjust fueling enrichment for MAP and not just rpm like PE, if ur running 20psi at 3000rpm or 5psi at 3000rpm each can be adjusted to suit, but on the PE only u have to be suited to 20psi for safety then lower boost is much richer then it needs to be (unless ur doing a full time OL tune) also a proper VE table is good as u can adjust any cell at a time where u cant on the vve, but either way if ur dialed in prob wouldnt notice the difference just personal preference
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07GTS
kittyboy said:
I figured, but really don't now why it's set at that level in the first place?
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thats just the point that factory sees the maf signal as a steadier value, below 4000rpm u spend most of the time day to day driving so a blend more so with the vve is good for throttle movements
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kittyboy
07GTS said:
personally i like the 2 bar OS (actually 2.5bar) as u get the BE table so u can adjust fueling enrichment for MAP and not just rpm like PE, if ur running 20psi at 3000rpm or 5psi at 3000rpm each can be adjusted to suit, but on the PE only u have to be suited to 20psi for safety then lower boost is much richer then it needs to be (unless ur doing a full time OL tune) also a proper VE table is good as u can adjust any cell at a time where u cant on the vve, but either way if ur dialed in prob wouldnt notice the difference just personal preference
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I made that observation regarding the PE at boost and watching the scanner at cruise. You confirm what I concluded to be the case with a richer mix at low boost. Entering data and calculating coefficients and zoning is really is a learning curve as well! So with the SD OS you can actually enter individual cell data without a coefficients operation completely re-interpret everything? Sounds like maybe I should give it a go?

The following close to getting it where I think is looks good up to 4000rpm-ish
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