Injector settings
Melting Slicks
Joined: Apr 2005
Posts: 3,418
Likes: 1
From: Chicagoland Area IL
100 = 14.5 PSI, not to be confused with standard atmosphere which is 14.7 psi (metric/standard thing). So depending on your elevation if near see level, simply subtract 100 to determine boost.
So 185-100 = 85
85/100 = 0.85
0.85*14.5 = 12.3 PSIG (psi guage) or your boost.
Maybe google standard day or standard atmosphere.
Last edited by Skunkworks; Oct 4, 2012 at 07:51 PM. Reason: Fixed bad info
Thread Starter
Racer
Joined: Jun 2012
Posts: 492
Likes: 1
I agree with Skunkworks the injectors are 82 lbs @ 4 bar.
The injector sizing chart that you have posted from my old files are set for a non boost referenced system as I mentioned when I emailed the file to you. My system does not accomodate positive pressure. In order to compensate for boost the numbers quickly change from 10 KPA manifold vacuum to the 3 bar 72 lb injector that they are at 15lbs of boost. The additional fuel required is added in by way of power enrichment. Boost referenced is a much better way to go as long as you have enough fuel at the higher presssure required when under boost.
The injector sizing chart that you have posted from my old files are set for a non boost referenced system as I mentioned when I emailed the file to you. My system does not accomodate positive pressure. In order to compensate for boost the numbers quickly change from 10 KPA manifold vacuum to the 3 bar 72 lb injector that they are at 15lbs of boost. The additional fuel required is added in by way of power enrichment. Boost referenced is a much better way to go as long as you have enough fuel at the higher presssure required when under boost.
EDIT: I just found a spread sheet on HPT's forum and it acually confirmed the numbers that I just calculated were correct.
Also what does everyone mean by "boost referenced"?
Last edited by ttz; Oct 3, 2012 at 01:57 PM.
Melting Slicks
Joined: Jul 2008
Posts: 3,002
Likes: 216
From: Houston Texas
2018 Corvette of Year Finalist
2017 C5 of Year Finalist
We are speaking in absolute terms not gauge terms. You will never see 0kPa with your engine. You may see 20 kPa under deep decel at which point the engine is pulling the fuel from the injector and the pulsewidth needs to be reduced or you will have an overfueling situation.
1bar = 14.5psia = 100kPa
Fuel pressure is set to 58 psi with the vacuum line disconnected. This simulates a pressure differential of zero across the injector. There isn't any manifold pressure pushing against the injector and there isn't vacuum creating low pressure.
If you have pressure or vacuum, it is compensated for mechanically with a 1:1 referenced regulator or in the case of the factory system the injector flow rate table. You can see that flow rate changes with changing MAP. This is to compensate for the pressure differential.
If you are using a 1:1 boost referenced regualtor, all of the values in the IFR table will be the same and not change. The regulator is mechanically compensating.
1bar = 14.5psia = 100kPa
Fuel pressure is set to 58 psi with the vacuum line disconnected. This simulates a pressure differential of zero across the injector. There isn't any manifold pressure pushing against the injector and there isn't vacuum creating low pressure.
If you have pressure or vacuum, it is compensated for mechanically with a 1:1 referenced regulator or in the case of the factory system the injector flow rate table. You can see that flow rate changes with changing MAP. This is to compensate for the pressure differential.
If you are using a 1:1 boost referenced regualtor, all of the values in the IFR table will be the same and not change. The regulator is mechanically compensating.
Last edited by Turbo-Geist; Oct 3, 2012 at 02:18 PM.
Pro
Joined: Feb 2005
Posts: 652
Likes: 16
From: Upton MA
I agree with Skunkworks the injectors are 82 lbs @ 4 bar.
The injector sizing chart that you have posted from my old files are set for a non boost referenced system as I mentioned when I emailed the file to you. My system does not accomodate positive pressure. In order to compensate for boost the numbers quickly change from 10 KPA manifold vacuum to the 3 bar 72 lb injector that they are at 15lbs of boost. The additional fuel required is added in by way of power enrichment. Boost referenced is a much better way to go as long as you have enough fuel at the higher presssure required when under boost.
The injector sizing chart that you have posted from my old files are set for a non boost referenced system as I mentioned when I emailed the file to you. My system does not accomodate positive pressure. In order to compensate for boost the numbers quickly change from 10 KPA manifold vacuum to the 3 bar 72 lb injector that they are at 15lbs of boost. The additional fuel required is added in by way of power enrichment. Boost referenced is a much better way to go as long as you have enough fuel at the higher presssure required when under boost.
Last edited by glennd; Oct 3, 2012 at 05:59 PM.
Melting Slicks
Joined: Apr 2005
Posts: 3,418
Likes: 1
From: Chicagoland Area IL
Built a spreadsheet while in meeting…
Here is data you asked for. But this is small part of what you need to successfully tune it.
0 kPa = 91.6 lb/hr
10 kPa = 90.7 lb/hr
20 kPa = 89.8 lb/hr
30 kPa = 88.8 lb/hr
40 kPa = 87.9 lb/hr
50 kPa = 87.0 lb/hr
60 kPa = 86.0 lb/hr
70 kPa = 85.0 lb/hr
80 kPa = 84.0 lb/hr
90 kPa = 83.0 lb/hr
100 kPa = 81.9 lb/hr
Edit - haven't messed with a C5 in a bit, so hope info isn't backwards... will check when I get home.
Here is data you asked for. But this is small part of what you need to successfully tune it.
0 kPa = 91.6 lb/hr
10 kPa = 90.7 lb/hr
20 kPa = 89.8 lb/hr
30 kPa = 88.8 lb/hr
40 kPa = 87.9 lb/hr
50 kPa = 87.0 lb/hr
60 kPa = 86.0 lb/hr
70 kPa = 85.0 lb/hr
80 kPa = 84.0 lb/hr
90 kPa = 83.0 lb/hr
100 kPa = 81.9 lb/hr
Edit - haven't messed with a C5 in a bit, so hope info isn't backwards... will check when I get home.
Last edited by Skunkworks; Oct 3, 2012 at 03:02 PM.
Melting Slicks
Joined: Apr 2005
Posts: 3,418
Likes: 1
From: Chicagoland Area IL
My numbers are correct in absolute context, but based on HP Tuners table, it should be:
100 kPa = 91.6 lb/hr
90 kPa = 90.7 lb/hr
80 kPa = 89.8 lb/hr
70 kPa = 88.8 lb/hr
60 kPa = 87.9 lb/hr
50 kPa = 87.0 lb/hr
40 kPa = 86.0 lb/hr
30 kPa = 85.0 lb/hr
20 kPa = 84.0 lb/hr
10 kPa = 83.0 lb/hr
0 kPa = 81.9 lb/hr
Oh also, see the reasoning for “0 kPa vacuum” cell being decreased a bit so PCM starts adding more fuel as you transition into boost and PE (power enrichment). Lots of ways to skin a cat.
I’ve just got so used to maxed out IFR tables lately, that I forgot some of the C5 stuff.
Last edited by Skunkworks; Oct 4, 2012 at 07:53 PM. Reason: Fixed bad info
Intermediate
Joined: Feb 2012
Posts: 40
Likes: 0
From: Fredericton New Brunswick
Built a spreadsheet while in meeting…
Here is data you asked for. But this is small part of what you need to successfully tune it.
0 kPa = 91.6 lb/hr
10 kPa = 90.7 lb/hr
20 kPa = 89.8 lb/hr
30 kPa = 88.8 lb/hr
40 kPa = 87.9 lb/hr
50 kPa = 87.0 lb/hr
60 kPa = 86.0 lb/hr
70 kPa = 85.0 lb/hr
80 kPa = 84.0 lb/hr
90 kPa = 83.0 lb/hr
100 kPa = 81.9 lb/hr
Edit - haven't messed with a C5 in a bit, so hope info isn't backwards... will check when I get home.
Here is data you asked for. But this is small part of what you need to successfully tune it.
0 kPa = 91.6 lb/hr
10 kPa = 90.7 lb/hr
20 kPa = 89.8 lb/hr
30 kPa = 88.8 lb/hr
40 kPa = 87.9 lb/hr
50 kPa = 87.0 lb/hr
60 kPa = 86.0 lb/hr
70 kPa = 85.0 lb/hr
80 kPa = 84.0 lb/hr
90 kPa = 83.0 lb/hr
100 kPa = 81.9 lb/hr
Edit - haven't messed with a C5 in a bit, so hope info isn't backwards... will check when I get home.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
Pro
Joined: Feb 2003
Posts: 745
Likes: 136
From: Detroit MI
Just looked at first post more closely and see HP tuners says Vacuum in kPa, not sure why GM would need to invert it. Well the whole “kPa” being an absolute engineering unit for pressure makes a vacuum impossible LOL. They should have used “kP” in description and dropped the absolute part, because you can’t go lower then 0, just like absolute temperature in degrees Rankine or Kelvin.
Thread Starter
Racer
Joined: Jun 2012
Posts: 492
Likes: 1
Alright, so I put the injectors in today and flashed those values into the flow rate vs. kpa section. It idled pretty lean. Around 16.3ish and as rough of course. I knocked the values down by x.96 and it helped. Also added to the pulse width adder. That made it a little better. Still rough idle and at about 15.4ish. Tap the throttle and it leans out a lot more. Now I'm stuck. I'm not sure if I should keep lowering the values in the flow rate vs. kpa table or if there is something else I should do. Another option is to use the values I posted in the first post since that was what the member I bought the injectors from was using. Those values just don't make sense to me. Any help would be much appreciated Thanks.
Premium Supporting Vendor
Joined: Oct 2004
Posts: 23,599
Likes: 1,224
From: Providing the most proven supercharger kits for your C5/6/7 609-752-0321
Your tune needs to be corrected, injector flow rate is a set value from a mechanical part. There are also several other settings that should be set as well but without that info from the manufacturer of the injector your shooting in the dark more or less. Hence just one of the reasons why I prefer ID injectors.
Melting Slicks
Joined: Apr 2005
Posts: 3,418
Likes: 1
From: Chicagoland Area IL
"kPa" is a unit, not an absolute scale. One kilopascal (kPa) is one thousands Pascals (Pa). The "a" in "kPa" is just the second letter of Pascal, not a reference to absolute anything. MAP is manifold absolute pressure, which is often listed in units of kPa. However, you can use kPa to describe a quantity of relative vacuum to ambient much the same way we often see "psi of vacuum." This is what GM happened to pick for a scale unit on early LS1 ECUs. Sure, it could have been described more clearly for the layperson but their calibration engineers seem to understand it just fine and it worked.
Melting Slicks
Joined: Apr 2005
Posts: 3,418
Likes: 1
From: Chicagoland Area IL
Alright, so I put the injectors in today and flashed those values into the flow rate vs. kpa section. It idled pretty lean. Around 16.3ish and as rough of course. I knocked the values down by x.96 and it helped. Also added to the pulse width adder. That made it a little better. Still rough idle and at about 15.4ish. Tap the throttle and it leans out a lot more. Now I'm stuck. I'm not sure if I should keep lowering the values in the flow rate vs. kpa table or if there is something else I should do. Another option is to use the values I posted in the first post since that was what the member I bought the injectors from was using. Those values just don't make sense to me. Any help would be much appreciated Thanks.
Lots more to it as mentioned then IFR table, that's probably easiest one to nail.
EDIT - HP Tuners has a compare function, use that.
Last edited by Skunkworks; Oct 4, 2012 at 08:01 PM.
Thread Starter
Racer
Joined: Jun 2012
Posts: 492
Likes: 1
So I finally got it to idle right. I ended up using the calculated values for my injector size but ended up having to multiply them all by .80 and increase my short pulse adder by 25%. Does this make any sense that the flow rate would be 20% lower than what its calculated value would be? Perhaps there was something else I should have changed instead? I tried using all the same settings as the member I get them from, but that made it mad lean. I also increased all VE by 2%. Prob shouldn't have though since airflow didn't change before or after the new injectors.
Melting Slicks
Joined: Apr 2005
Posts: 3,418
Likes: 1
From: Chicagoland Area IL
Larger injectors are more sluggish then smaller ones - a generalization. Not knowing where your short pulse adder is, I’d add more (+25%) to your short pulse and also start bringing IFR table back to where it should be. When engine is idling, short pulse adder contributes significantly to fueling. It’s compensating for non-linear region. Disclaimer, dialing in short pulse is tricky and best done with actual test data. Also the bigger the injector, the more critical.
You still have to tackle voltage table too. Think RC injectors are popular with imports so you may find info on the web and then interpolate voltage related data. This table characterizes latency vs voltage.
You may have better luck on HP Tuners forum then here.
You still have to tackle voltage table too. Think RC injectors are popular with imports so you may find info on the web and then interpolate voltage related data. This table characterizes latency vs voltage.
You may have better luck on HP Tuners forum then here.
Thread Starter
Racer
Joined: Jun 2012
Posts: 492
Likes: 1
Still can't get this right. If I try to go closer to the calculated flow rate of the injectors and raise the short pulse adder, I can get it to idle fine around 0 in the fuel trims, but as soon as you give it any throttle it goes very rich. Around 10:1-11:1 AFR. If I try a compromise and increase short pulse adder by 50% over stock and have the flow rates at 85% of the calculated values, same thing. The fuel trim eventually even it out of course, but they are adding 10% at idle, then if given any throttle it goes rich again. I know messing with the VE tables (2 bar SD tune) would fix this all, but that doesn't seem like a good idea since my air flow never changed, so this s obviously and injector tune issue. Ideas?
Melting Slicks
Joined: Jul 2008
Posts: 3,002
Likes: 216
From: Houston Texas
2018 Corvette of Year Finalist
2017 C5 of Year Finalist
What VE values are you currently using? They may have been correct for your previous injectors, but it doesn't sound like they are working for your current ones.
I have a stock 99 LS1 with stock heads and cam and ID1000 injectors. There isn't one cell in my VE table that is stock. I've always looked at the VE table as a fueling table in SD mode. The VE table is where you are going to make all of your fueling corrections once you get the intitial parameters close.
I have a stock 99 LS1 with stock heads and cam and ID1000 injectors. There isn't one cell in my VE table that is stock. I've always looked at the VE table as a fueling table in SD mode. The VE table is where you are going to make all of your fueling corrections once you get the intitial parameters close.
Thread Starter
Racer
Joined: Jun 2012
Posts: 492
Likes: 1
What VE values are you currently using? They may have been correct for your previous injectors, but it doesn't sound like they are working for your current ones.
I have a stock 99 LS1 with stock heads and cam and ID1000 injectors. There isn't one cell in my VE table that is stock. I've always looked at the VE table as a fueling table in SD mode. The VE table is where you are going to make all of your fueling corrections once you get the intitial parameters close.
I have a stock 99 LS1 with stock heads and cam and ID1000 injectors. There isn't one cell in my VE table that is stock. I've always looked at the VE table as a fueling table in SD mode. The VE table is where you are going to make all of your fueling corrections once you get the intitial parameters close.
Melting Slicks
Joined: Feb 2006
Posts: 2,163
Likes: 5
From: Houston
The VE and IFR tables are going to need some give and take once you plug in the correct numbers whether they were supplied by the vendor or hand calculated. To think you can swap in injectors and just plug in data w/o having to do a decent bit of tuning to the VE table is crazy. There are so many damn multipliers in the stock ecm, and who knows what HPT has not uncovered that is going on in there. If you injector data is pretty close, and the car runs great by dialing in the VE, move on. That VE is not the real VE of the engine, and it never will be.
Then once you think you have it all perfect you decide to tune the boost value. BAM, p01514 and reduced power mode...lol. You have to scale both the IFR and VE to get around this limitation, and now you really see where these numbers are just relative and not absolute for our application ..
Then once you think you have it all perfect you decide to tune the boost value. BAM, p01514 and reduced power mode...lol. You have to scale both the IFR and VE to get around this limitation, and now you really see where these numbers are just relative and not absolute for our application ..
Melting Slicks
Joined: Jul 2008
Posts: 3,002
Likes: 216
From: Houston Texas
2018 Corvette of Year Finalist
2017 C5 of Year Finalist
In addition, if you are spraying a lot of methanol you have to have a way to reduce how much gasoline is injected or else your A/F ratio will be extremely rich.
I don't have the IAT fuel correction table because my car is a 99 model. Plus, I would only use that as a failsafe to increase fuel if the meth failed. I wouldn't use it to control fueling during meth injection.
The only way to handle the meth injection is via the VE table. There are areas of my VE map that are less than 100 when I am at full boost. Once you look at the VE table as a complete system involving fueling and airflow, it becomes a tool for dialing it in correctly.
I'm sure it was accurate when dealing with a stock N/A vehicle with a MAF sensor. Once you go to a 3 bar SD tune, trying to make those numbers represent real world air flow doesn't seem possible.
Am I missing something here? Are other people doing something different from a tuning standpoint when dealing with stock ecm, large injectors, speed density, and greater than 15 psi?
I don't have the IAT fuel correction table because my car is a 99 model. Plus, I would only use that as a failsafe to increase fuel if the meth failed. I wouldn't use it to control fueling during meth injection.
The only way to handle the meth injection is via the VE table. There are areas of my VE map that are less than 100 when I am at full boost. Once you look at the VE table as a complete system involving fueling and airflow, it becomes a tool for dialing it in correctly.
I'm sure it was accurate when dealing with a stock N/A vehicle with a MAF sensor. Once you go to a 3 bar SD tune, trying to make those numbers represent real world air flow doesn't seem possible.
Am I missing something here? Are other people doing something different from a tuning standpoint when dealing with stock ecm, large injectors, speed density, and greater than 15 psi?