What to Tune First

[TAQuickness]

This is not the end-all-be-all bible to tuning. It's just 1 of 101 ways to tune that delivers consistant and repeatable results. As of late, I have read a few tuning books that reinforce this methodology.
IFR Table {B4001}: Very important that you start here and get this table right. You should use the IFR spreadsheet (http://www.marcintology.com/tuning/injectors.xls) RedHardSupra made available on his website (or a similar one). This is the one known constant that you will base the rest of your tune on.
VE Table {B0101}: You will use the AutoVE tutorial (http://download.efilive.com/Tutorials/PDF/AutoVE%20Tuning%20Tutorial.pdf) to get this table dialed in. This will establish the base air mass model for your engine.
*Optional* MAF Table {B5001}: The same concepts you learn tuning the VE table with the AutoVE tutorial are to be applied to the MAF table.
Idle & Idle Transistion tables. Ironically, idle is the first thing your engine does and one of the last things to get tuned. An engine that won't idle is a frustrating driving experience - BUT, you must complete the previous steps to derive an accurate air and fuel mass flow model in order to achieve desirable idle quality. SSpdDmon has posted some great idle tuning information here (http://forum.efilive.com/showthread.php?t=4661)
Spark Tables: You will need a load bearing dyno to accurately dial in your spark. Basically you just advace until you make no more torque/power then back off 2* for safety.
WOT: Best to do at the same time as your spark tuning to save on dyno $. In this case you will be adjusting spark & fuel to achieve maximum torque and horsepower.

[jfpilla]

This is not the end-all-be-all bible to tuning. It's just 1 of 101 ways to tune that delivers consistant and repeatable results. As of late, I have read a few tuning books that reinforce this methodology.

I think there is one best way. It's at times elusive, but with what you describe it probably ends up being easier than chasing ones tail from a patched tune.

There are always questions posted about where to start first.

This should be a sticky!

[VTC_WS6]

Excellent info, had I had my IFR's down correctly I wouldn't have spent the last 2 days chasing my own tail.

[SSpdDmon]

Something I've been trying lately...



Another theory to chew on that I have tried and posted before...
RPM Threshold for Airflow Calc {B0120}: Using your stock, screened MAF, set this threshold to 100rpm to enable a full, MAF-only tune. The purpose of this is to reverse engineer your IFR table based on how the injectors flow in YOUR car.
IFR Table {B4001}: Based on what you believe to be true about your injectors, you should use the IFR spreadsheet (http://www.marcintology.com/tuning/injectors.xls) RedHardSupra made available on his website (or a similar one) to initially set this table. Then using the reciprical of your BEN factor for your WBO2 along with the MANVAC pid, you'll correct this table. Remember, raising values lean out AFRs and reducing values richen AFRs in this table. This will become an important constant that you will base the rest of your tune on.
VE Table {B0101}: After returning the B0120 to stock and setting your tune per the the AutoVE tutorial (http://download2.efilive.com/Tutorials/PDF/AutoVE%20Tuning%20Tutorial.pdf), you can begin to get this table dialed in. This will establish the base air mass model for your engine.
*Optional* MAF Table {B5001}: The same concepts you learn tuning the VE table with the AutoVE tutorail are to be applied to the MAF table. Although using this method, there shouldn't be much adjustment needed for this table due to steps 1 and 2.
Idle & Idle Transistion tables. Ironically, idle is the first thing your engine does and one of the last things to get tuned. An engine that won't idle is a frustrating driving experience - BUT, you must complete the previous steps to derive an accurate air and fuel mass flow model in order to achieve desirable idle quality. SSpdDmon has posted some great idle tuning information here (http://forum.efilive.com/showthread.php?t=4661).
Spark Tables: You will need a load bearing dyno to accurately dial in your spark. Basically you just advace until you make no more torque/power then back off 1~2* for safety. Remember, things like compression ratios and altitude can effect the amount of timing your engine will run best at.
WOT: Best to do at the same time as your spark tuning to save on dyno $. In this case you will be adjusting spark & fuel to achieve maximum torque and horsepower.
Sorry, I stole your format TAQ 'cuz I'm lazy these days. :)

[jfpilla]

SD,
Step 1 looked very interesting, so I tried it today. I'm happy to say my MAF table was right on. Commanded and Actual AFR tracked very well and Ltrims were good. It seems step 1 is essentially a "super filter", eliminating transition impact from the VE's. My filters must be good. I like this idea and will play some more.
A couple of questions:
If you have programmed IFRs and have tuned the MAF why would you retune the IFRs since the MAF has now compensated?
Also, if the MAF is now correct why redo it with B0120 at 4000 rpms, since you can't turn off the VE's and have eliminated transitions it would seem everything is already correct?
Thanks
Joe

[SSpdDmon]

SD,
Step 1 looked very interesting, so I tried it today. I'm happy to say my MAF table was right on. Commanded and Actual AFR tracked very well and Ltrims were good. It seems step 1 is essentially a "super filter", eliminating transition impact from the VE's. My filters must be good. I like this idea and will play some more.
A couple of questions:
If you have programmed IFRs and have tuned the MAF why would you retune the IFRs since the MAF has now compensated?
Also, if the MAF is now correct why redo it with B0120 at 4000 rpms, since you can't turn off the VE's and have eliminated transitions it would seem everything is already correct?
Thanks
Joe
This is starting with an untuned car. The idea is you keep the stock MAF curve and build the IFR and VE tables off of it instead of using what the IFR should be (which it may not really be in reality) and building the VE/MAF. I ran my 23x/23x H/C Camaro this way...threw a stock tune in and turned the VE off. It ran pretty good right off the bat, which makes sense because the MAF was doing a pretty good job of reading the incoming airflow based on the stock curve.

The reason why I suggest this is because the stock MAF has a great deal of R&D into it on flowbenches to determine the airflow values. When you change the VE with a head/cam swap or change out the injectors, why should the MAF change so much? You didn't drastically alter the way the MAF functions. Then again, assuming you don't change the injectors, this theory is questionable.

I guess either way you choose to tune, I believe there is an unavoidable fudge factor. It's just where you choose to fudge that determines the style of tuning you do.

[odd boy]

Guys,

I've some questions:

1. Assume that I didn't upgrade the stock injectors, do I need to tune IFR Table {B4001}.

2. why don't we keep the MAF on all the time and keep VE off?

[SSpdDmon]

Guys,

I've some questions:

1. Assume that I didn't upgrade the stock injectors, do I need to tune IFR Table {B4001}.

Yes or no depending on how you choose to tune. Trying it my way (leaving MAF curve stock), you would end up tweaking the IFR before touching the VE. Using the orginal method, no - you wouldn't touch the 17 IFR cells. You would tweak the 85+ MAF cells though.

2. why don't we keep the MAF on all the time and keep VE off?

The theory is that the MAF sensor is optimal for steady airflow. During transitions, a VE or blended MAF/VE table is better. At least, that's the theory.


:crash: :)

[joecar]

My understanding of when is MAF or VE used:
- Below B0120: combination of MAF table (steady state) and/or VE table (transitions).
- Above B0120: MAF table.

EDIT: corrected my post.

[jfpilla]

My understanding of when is MAF or VE used:
- Below B0120: combination of MAF table and/or VE table.
- Above B0120: MAF table.


So the VE still kicks in during throttle transitions, which means you'll have to filter these out completely.

- Throttle Transitions: VE table, regardless of B0120.

If engine speed is above this value, then the PCM will use the MAF sensor exclusively (if not disabled by DTCs) to calculate grams of air per cylinder.

This is the EFI descriptionof B0120. Is it wrong?

[SSpdDmon]

So the VE still kicks in during throttle transitions, which means you'll have to filter these out completely.

Regardless of whether or not the first part of this statement is accurate, I consider tuning out transitional data in my logs a standard practice....based on the assumption that if you get things working right during the consistent scenarios (between MAF/VE/Injectors), the transitions should fall into place.

[TAQuickness]

Good stuff Jeff. I'll give this a shot with the new build.

[jfpilla]

So the VE still kicks in during throttle transitions, which means you'll have to filter these out completely.

I must be slow.:unsure:
If it still kicks in what does setting B0120 to 100rpms do?

[VTC_WS6]

RPM Threshold for Airflow Calc {B0120}: Using your stock, screened MAF, set this threshold to 100rpm to enable a full, MAF-only tune. The purpose of this is to reverse engineer your IFR table based on how the injectors flow in YOUR car.



Now in the case you're using a set of large injectors right off the bat, I presume this will cause an issue if I were to just toss a fresh base map in there and begin with this approach (w/o regard to IFR), is this correct?

[dc_justin]

- Throttle Transitions: VE table, regardless of B0120.

So the VE still kicks in during throttle transitions, which means you'll have to filter these out completely.

From all of my testing, I would have to disagree and say that once B0120 condition is met, MAF is used exclusively airflow calculation, transient condition or not.

Justin

[joecar]

From all of my testing, I would have to disagree and say that once B0120 condition is met, MAF is used exclusively airflow calculation, transient condition or not.

Justin
Oh, it does...? Then I'm wrong, I stand corrected and I edited my post: showpost.php?p=68499&postcount=9 (http://forum.efilive.com/showpost.php?p=68499&postcount=9)

[jfpilla]

From all of my testing, I would have to disagree and say that once B0120 condition is met, MAF is used exclusively airflow calculation, transient condition or not.

Justin

Thanks Justin,
It would make no sense, otherwise. I'll run some longer scans and see what I can, anyway. I like this idea.
Joe

[joecar]

Thanks, I'm going to rerun some of my experiments (zero out VE table and B0120)... :bangin:...I'm now sure I goofed up along the way... :doh2:

This means that an AutoMAF tune should be very easy...


- Throttle Transitions: VE table, regardless of B0120.

If engine speed is above this value, then the PCM will use the MAF sensor exclusively (if not disabled by DTCs) to calculate grams of air per cylinder.

This is the EFI descriptionof B0120. Is it wrong?
Regardless of whether or not the first part of this statement is accurate, I consider tuning out transitional data in my logs a standard practice....based on the assumption that if you get things working right during the consistent scenarios (between MAF/VE/Injectors), the transitions should fall into place.
So the VE still kicks in during throttle transitions, which means you'll have to filter these out completely.

I must be slow.:unsure:
If it still kicks in what does setting B0120 to 100rpms do?
From all of my testing, I would have to disagree and say that once B0120 condition is met, MAF is used exclusively airflow calculation, transient condition or not.

Justin
Thanks Justin,
It would make no sense, otherwise. I'll run some longer scans and see what I can, anyway. I like this idea.
Joe
And my partial-point about transient filtering was not lost... :cheers: ..I am having a day, arn't I... :banana::cucumber: ...I'm always learning.

[jfpilla]

Thanks, I'm going to rerun some of my experiments (zero out VE table and B0120)... :bangin:...I'm now sure I goofed up along the way... :doh2:

This means that an AutoMAF tune should be very easy...



And my partial-point about transient filtering was not lost... :cheers: ...I am having a day, arn't I... :banana::cucumber:

Joe:coool:,
Your contributions are appreciated. The icon is not too subtle, is it?
Joe

[SSpdDmon]

Now in the case you're using a set of large injectors right off the bat, I presume this will cause an issue if I were to just toss a fresh base map in there and begin with this approach (w/o regard to IFR), is this correct?
I haven't tried to do this with stock injectors. I don't know for sure how it would fair. If you do try it, proceed with caution and let us know what kind of results you get. To be safe, you could try reducing the stock IFR table some just incase...

Remember, this method is in recognition of the idea that something is being fudged. Whether it's the MAF or the IFR table, something isn't right. As a result, we're trying to deal with it the best we can. My goal here is to get some 'outside the box' thinking going - especially since the opening line of this thread is....

This is not the end-all-be-all bible to tuning. It's just 1 of 101 ways to tune that delivers consistant and repeatable results.

:)

[dfe1]

From all of my testing, I would have to disagree and say that once B0120 condition is met, MAF is used exclusively airflow calculation, transient condition or not.

Justin
I believe you're correct. I have an email from a GM engine control engineer that states MAF is used exclusively above what we know as the B0120 data point and that the system uses a combination of MAF and VE below that point, depending on whether the engine is in steady state or transient mode. The only time it uses VE exclusively is in the event of a MAF failure. The actual e-mail is on another computer-- I'll post it tomorrow.

For what it's worth, I've felt for a long time that below the B0120 point, the switch between VE table and MAF input operates along the lines of the high and low octane scalar-- it's never exclusively one or the other, but biased one way or the other depending on operating conditions. In this case, engine speed rate of change alters the bias. I don't know this for a fact, but all my experimenting points in that direction. After being the recipient of flack and other foreign matter about my cat-skinning procedure, and the rough edges it might leave, I put a vehicle that I had tuned using only changes to the VE table, into speed/density. The changes I see in long term fuel trims range between 0 and 12%, but there doesn't seem to be any consistency in the degree of change during steady state operation, as opposed to during throttle transitions. I need to do some more logging to see if any type of pattern exists.

[joecar]

Don't think of it as flack, think of it as a challenge or a debate... ;)

[odd boy]

Guys,

Since I'm new to tuning world, you can ignore whatever I say !!!! :rolleyes:

I think if I want to achieve the desired AFR value, either change the air [through {B0101} and/or {B5001}] or play with fuel [through {B4001}]. Why adjust both since it is ratio :anitoof:


:coool::coool::coool:

[dfe1]

Don't think of it as flack, think of it as a challenge or a debate... ;)
I have a wife and two daughters-- I know flack when I see it. ;)

[jfpilla]

Guys,

Since I'm new to tuning world, you can ignore whatever I say !!!! :rolleyes:

I think if I want to achieve the desired AFR value, either change the air [through {B0101}
xxxxB0101 would be used to change AFR in OL or SD.
and/or {B5001}]
xxxxB5001 is calibrated at WOT so that commanded AFR B3618 matches actual AFR.
or play with fuel [through {B4001}]
xxxxB4001 settings are either stock or calculated, IMO.
. Why adjust both since it is ratio :anitoof:


:coool::coool::coool:
Does this help?

[joecar]

I have a wife and two daughters-- I know flack when I see it. ;)Man, you're outnumbered... :w00t:

[odd boy]

xxxxB5001 is calibrated at WOT so that commanded AFR B3618 matches actual AFR.



Do you mean under WOT the PCM calculates the AFR through {B5001} and {B3618} only?

Would you tell me more about how the PCM works under WOT condition?

thanks a llllllllllllllllot

[jfpilla]

Do you mean under WOT the PCM calculates the AFR through {B5001} and {B3618} only?
xxxxx Some think VE's are involved, but I haven't noted any difference when VE's are changed.

Would you tell me more about how the PCM works under WOT condition?

thanks a llllllllllllllllot

I don't get the WOT condition question?

[joecar]

Is this what you're asking:

At WOT:
- the PCM calculates the airmass from the MAF (B5001),
- the PCM looks up the commanded AFR from PE (B3618),
- the PCM uses those two to calculate fuelmass,
- the PCM looks up the injector flow rate from IFR (B4001),
- the PCM uses those two to calculate the injector pulse width.

At WOT, airmass would come from B5001 since rpm is above B0120.
At WOT, PE would be enabled, and B3618 would be richer than B3605, so B3618 wins.
At WOT, MANVAC would be zero, so first cell of B4001 is the injector flow rate.

[jfpilla]

Joe,
Thanks.

oddboy?mmm:music_whistling_1:
The last items I tune are spark and wot AFR.
That keeps everything else constant.
JP

[dfe1]

Following is the information supplied to me by a GM engine control specialist:
The engine control module uses a combination of the MAF
sensor and the MAP sensor to compute trapped cylinder air mass, which is
used as a critical operating parameter for much of the control system.

When the engine is in a "steady state" situation, the MAF sensor
measurement is an accurate representation of trapped cylinder air mass. A
"steady state" is defined as when actuators (such as the throttle or cam
phasing) that control air flow into or out of the manifold are not moving.
In this circumstance, the mass of air in the intake manifold is stable.

If one of those actuators is moving, it will generally cause the mass of
air in the intake manifold to change. Because of this change of air mass
in the manifold, the MAF sensor (which measures air entering the manifold)
is not correctly measuring the air in the cylinder (which is the mass of
air exiting the manifold). This transient phenomenon is called "manifold
filling (or emptying)".

During these transient maneuvers, the MAP sensor is a more accurate
representation of the state of the air entering the cylinder. Therefore, a
speed density calculation (using the MAP as its basis) is used during these
transient situations.

The only scenario where the MAP sensor is used exclusively is in case of a
MAF sensor failure.

[SSpdDmon]

Following is the information supplied to me by a GM engine control specialist:
The engine control module uses a combination of the MAF
sensor and the MAP sensor to compute trapped cylinder air mass, which is
used as a critical operating parameter for much of the control system.

When the engine is in a "steady state" situation, the MAF sensor
measurement is an accurate representation of trapped cylinder air mass. A
"steady state" is defined as when actuators (such as the throttle or cam
phasing) that control air flow into or out of the manifold are not moving.
In this circumstance, the mass of air in the intake manifold is stable.

If one of those actuators is moving, it will generally cause the mass of
air in the intake manifold to change. Because of this change of air mass
in the manifold, the MAF sensor (which measures air entering the manifold)
is not correctly measuring the air in the cylinder (which is the mass of
air exiting the manifold). This transient phenomenon is called "manifold
filling (or emptying)".

During these transient maneuvers, the MAP sensor is a more accurate
representation of the state of the air entering the cylinder. Therefore, a
speed density calculation (using the MAP as its basis) is used during these
transient situations.

The only scenario where the MAP sensor is used exclusively is in case of a
MAF sensor failure.

Based on what he's saying, it begs the question - why would we need a MAF? :devil_2:

[redhardsupra]

maf is way easier to tune
maf is very good at steady state
maf relies on one sensor instead of a bunch of them--more reliable

[jfpilla]

Based on what he's saying, it begs the question - why would we need a MAF? :devil_2:

Boring:nuke:

[SSpdDmon]

maf is way easier to tune
maf is very good at steady state
maf relies on one sensor instead of a bunch of them--more reliable


Boring:nuke:

eye no - just playing devils advocate. :)

[jfpilla]

eye no - just playing devils advocate. :)

I thought you were pulling our chains.:rolleyes:

[ScarabEpic22]

No MAF for me fellas!:banana: GM designed the P10 without a MAF and still got the power and economy they needed. That said, in late 05 when they redesigned the I6 GM gave it a MAF...

[odd boy]

Is this what you're asking:

At WOT:
- the PCM calculates the airmass from the MAF (B5001),
- the PCM looks up the commanded AFR from PE (B3618),
- the PCM uses those two to calculate fuelmass,
- the PCM looks up the injector flow rate from IFR (B4001),
- the PCM uses those two to calculate the injector pulse width.

At WOT, airmass would come from B5001 since rpm is above B0120.
At WOT, PE would be enabled, and B3618 would be richer than B3605, so B3618 wins.
At WOT, MANVAC would be zero, so first cell of B4001 is the injector flow rate.

Exactly to the point, many thanks to you both Joe and jfpilla.

[BrianC98Z28]

Question.... because ive been following this thread. on my buddies 403 we put a 85mm maf on his car and I put a ls6 maf table in it and it seems to be doing WAY better than it was with a "professional" tune with the stock maf. I know 01+ Z06s came with 85mm mafs so I figured a good starting point would be the ls6 maf table. How do I go about further tuning the maf correctly to get it all dialed in because I saw there is already so MAF maps made from efilive

[TAQuickness]

Depends on your method of tuning. Per concept 1, you would use the same principles of the AutoVE tutorial and apply them to the MAF table. Per concept 2 (guys chime in if I misunderstood) you would accept your MAF table as a constant and tweak your IFR table.

[SSpdDmon]

Depends on your method of tuning. Per concept 1, you would use the same principles of the AutoVE tutorial and apply them to the MAF table. Per concept 2 (guys chime in if I misunderstood) you would accept your MAF table as a constant and tweak your IFR table.
Correct - assuming you have the right MAF table for the hardware you're running and you've dumped the B0120 threshold to something below normal operation (i.e. 100rpm).

[BrianC98Z28]

i understand how to do the autove but when you say use the same principles what exactly do you mean?? Can you use one of the MAF maps that efi already has i.e (im not on my comp with the software) so i dont remember exact titles but its something like MAF Configuration BEN LC1 or something like that and log the data with the maf reenabled and log that data and make the correction in the tune and smooth and then be good to go in that area or am i way off par here??

[joecar]

Brian, yes that is correct, you apply the MAF BEN map to the MAF table (using copy-with-labels and paste-multiply-with-labels).

[BrianC98Z28]

thanks joe just making sure i understood it right

[VTC_WS6]

Has anybody found their OE MAF's to be in need of extensive calibration as is? I ask because I at this point of MAF is stock and I'm not really sure if I stand to benefit from MAF adjustments or am I just 'over complicating' things?

[jfpilla]

Brian,
I think part of your question was missed. Remain in SD when logging B5001.
Joe

[VTC_WS6]

Brian, yes that is correct, you apply the MAF BEN map to the MAF table (using copy-with-labels and paste-multiply-with-labels).

By 'MAF table' you are refering to B5001 correct?

Side question, with all this tuning of the MAF I got to thinking and I'd like to confirm what I belive to be correct. As I understand it, If one were to drop the MAF threshold for calc. (B0120) to say 100rpm, you basically force the PCM to use the MAF sensor exclusivley for airflow calculation. Now you can set CL enable (B4205) to a higher than expected limit (say 122*C) and you now for the PCM to operate in OL. At this point I assume two things, first the PCM will derive fueling calculations from B3605 (when not at WOT/PE mode) exclusivley, with actual fuel delivery being influenced by the IFR table of course, and secondly, one could at least theoretically set the EQ modifier for the PE tables to '1.00' (or just disable PE mode altogether) thereby making B3605 the sole source of fueling calculations at all times. No MAP, no VE, no O2 input.

Now i'm not saying this is the 'right' or 'wrong' way to do anything, I'm just trying to get a better grasp on exactly how the PCM logic operates on a basic level.

[VTC_WS6]

Depends on your method of tuning. Per concept 1, you would use the same principles of the AutoVE tutorial and apply them to the MAF table. Per concept 2 (guys chime in if I misunderstood) you would accept your MAF table as a constant and tweak your IFR table.


Correct - assuming you have the right MAF table for the hardware you're running and you've dumped the B0120 threshold to something below normal operation (i.e. 100rpm).

But how exactly are you logging the IFR? I read:



IFR Table {B4001}: Based on what you believe to be true about your injectors, you should use the IFR spreadsheet RedHardSupra made available on his website (or a similar one) to initially set this table. Then using the reciprical of your BEN factor for your WBO2 along with the MANVAC pid, you'll correct this table. Remember, raising values lean out AFRs and reducing values richen AFRs in this table. This will become an important constant that you will base the rest of your tune on.

..I'm just not understanding what you are actually logging? When I open a new map in Scantool for example, I use the MANVAC pid as my row, use the BEN LC1 factor as the data but what am I using for the column, and how is the commanded AFR not influencing the final amount of fuel injected? Or should I be setting the same commanded AFR for an entire section of B3605 (say setting all rows 60-80*C ECT at 12.5 AFR) and then driving the car and hitting as many vacuum points as I can and then using the difference in commanded AFR and actual AFR to set the IFR amounts? (Did I just answer my own question? :redface:)

[BrianC98Z28]

Brian,
I think part of your question was missed. Remain in SD when logging B5001.
Joe


You stay in SD when dialing in the maf?? I thought youd dial it in with it reenabled, because in SD its disabled.

[Kurtomac]

dumb guy input....if you were not in SD wouldnt your fuel trims start jacking stuff up vi the 02 sensors

[jfpilla]

You stay in SD when dialing in the maf?? I thought youd dial it in with it reenabled, because in SD its disabled.
It's not really disabled. The functions that rely on the MAF are disabled. If you look at a SD log you will see the MAF still reports, but without any trim interference.

You can calibrate the MAF by way of LTFTs, but it's tedious and old school.
Joecar can probably give a more technical explanation.
I should have mentioned this part is CL.

[SSpdDmon]

But how exactly are you logging the IFR? I read:



..I'm just not understanding what you are actually logging? When I open a new map in Scantool for example, I use the MANVAC pid as my row, use the BEN LC1 factor as the data but what am I using for the column, and how is the commanded AFR not influencing the final amount of fuel injected? Or should I be setting the same commanded AFR for an entire section of B3605 (say setting all rows 60-80*C ECT at 12.5 AFR) and then driving the car and hitting as many vacuum points as I can and then using the difference in commanded AFR and actual AFR to set the IFR amounts? (Did I just answer my own question? :redface:)

You're logging your BEN as the data point, MANVAC as indicated in the IFR, and a single RPM column (use label ,8000 - yes use the comma). The difference is, the change you need to make to the IFR table is the inverse of your BEN. In other words, if your BEN for the 45kPa cell in your log is 1.02 (indicating a 2% lean situation), you would apply a 2% reduction to the 45kPa cell in the IFR table. This is because the computer is assuming that the injector needs to stay open 'x' miliseconds based on the flow rate provided when really it needs to stay open a little longer. The way you get the injector to stay open longer is to tell the PCM it flows less. Really, that's what you're trying to fix. If the MAF is saying 'y' grams of airflow per second, the PCM calculates 'z' grams per cylinder of air. Then, it delivers the appropriate amount of fuel. Well, if you're 2% lean, then one of the variables is wrong. If the MAF is flowbench tested and R&D'd out the wazoo like most GM guys will claim, I say change a different variable. In this case, that would be injector flow rate.

After your IFR has been constructed off your MAF, then you go back and dial in the VE for that IFR table. This is what sets this type of IFR tuning apart from the 2hour 'pro' dyno tune.

[joecar]

The IFR table column is PID-less and unitless, so you can use an already logged PID like RPM.

A calc pid can be made for calculating 1/BEN and this is what is paste-multiplied to the IFR table, as SSpdDmon said (these is no paste-divide-by).

[redhardsupra]

so you're setting IFR from MAF? and how do you determine MAF? fueling calculations using fuel flow and wideband? oh wait, we're back to IFR...

jeff, what was first, the chicken or the egg?

[jfpilla]

This is an arguement that goes on and on.

I've always been told and read that the MAF is "bench calibrated" but for the injectors it will mate up with. There is nothing sacred about the stock calibration.
Tuning via IFR always ends up with eneven values(curve). I've never seen anything but a straight factory curve.
Suggest that Injectors be flow tested, it's cheap insurance towards a good tune, set the IFR and match the MAF to the injectors.

Just my opinion.

[jfpilla]

so you're setting IFR from MAF? and how do you determine MAF? fueling calculations using fuel flow and wideband? oh wait, we're back to IFR...

jeff, what was first, the chicken or the egg?

Very cute:mrgreen:

[SSpdDmon]

so you're setting IFR from MAF? and how do you determine MAF? fueling calculations using fuel flow and wideband? oh wait, we're back to IFR...

jeff, what was first, the chicken or the egg?
Answer: Neither...theropods came first. If you want to look at it less technically, the egg came first since the chicken evolved to what it is today.

http://www.pbs.org/lifeofbirds/evolution/index.html

;)

As for the MAF method I've been pushing, I still claim it's no more right or wrong than any other method. It's just different...and remember, just because something's different doesn't mean it's deficient. :D Also, I never claimed you would tune yourself to a linear result in the IFR. You can get close though - then find the best line that satisifies most of the cells within a few percent and then tweak with the MAF. End result, a fairly stock looking MAF curve and adhearance to the timing table. Blow the MAF out of proportion and your granularity changes in the timing tables. Plus, with this way you don't max out the MAF by 10,000hz.

[jfpilla]

Also, I never claimed you would tune yourself to a linear result in the IFR.

My point was the opposite. GM's IFR curve is always linear. I mean to use that point as evidence that the IFR curve should not be anything but linear.
I'm missing your meaning about granularity?

[SSpdDmon]

Also, I never claimed you would tune yourself to a linear result in the IFR.

My point was the opposite. GM's IFR curve is always linear. I mean to use that point as evidence that the IFR curve should not be anything but linear.
I'm missing your meaning about granularity?
Oh, I must have misunderstood your IFR point.

Stock MAF curve tuned, my '01 H/C SS saw ~.76 grams/cyl IIRC. Using the method seen in the tutorial (set IFR, tune VE, tune MAF), I bumped up the frequency so much to get the AFR right that the PCM was now showing .86~.88 grams/cyl. Look at the timing table and see what it does....it shifts everything to the right (i.e. lower timing). Maybe a better analogy would be - it's like stretching an image on your desktop from 600x600 to 800x600. It also means you jump across the cells a little more. In my experience, the more you jump across the timing cells at low RPM, the probability of surging/bucking occuring increases.

[redhardsupra]

both IFR and MAF are smooth functions out of factory. the fact that we must screw at least one of them up to get a decent tune means (to me) that there's a hidden variable (or a dozen).

i'm not saying that one method is better than another either, however, i did say they're all equivalent, and we need a solid starting point. this is my way of arguing chicken vs egg: http://redhardsupra.blogspot.com/2008/04/three-airmass-models.html

[TAQuickness]

I believe part of the hidden variables fall within the injector tables, namely the off-set table, hence the fudgin in the air mass tables.

Given that something has to be fudged, I'm way more comfortable setting up the fuel mass tables to a known constantan and utilizing the air mass tables for fudging due to the higher resolution available in the air mass tables.

BUT, I like Jeff's out of the box thinking and am willing to give it a shot.

Even if a tuning bible were available, we'd each develop our own methods of tuning based on our interpretation of the bible. So long as our methods delivered consistant results, they'd be no better or worse than the next guys.

[redhardsupra]

Even if a tuning bible were available, we'd each develop our own methods of tuning based on our interpretation of the bible.
Monty Python says: SPLITTERS! ;)

on a more serious note tho, i got to work on my ford2gm characteristics spreadsheet last night, i think i'm close to finishing it. it should help out a lot with wacky behaviors from injectors. any testers?

[jfpilla]

It's likely that many factors are involved. Maybe even mis-matched mods.Like toolargeinjectors. You can get a look at the offset results. These are mine. Stock offset table and stock injectors. It's a WOT run.

[TAQuickness]

Monty Python says: SPLITTERS! ;)

on a more serious note tho, i got to work on my ford2gm characteristics spreadsheet last night, i think i'm close to finishing it. it should help out a lot with wacky behaviors from injectors. any testers?

I'm game to have a look at it. Both my LC-1's are shot ATM so I'm not so willing to flash any changes to my tune yet.

[dfe1]

on a more serious note tho, i got to work on my ford2gm characteristics spreadsheet last night, i think i'm close to finishing it. it should help out a lot with wacky behaviors from injectors. any testers?
Since I never purchased the Rental Car Tuning Option (RCTO), I'll have to do the testing on my personal vehicles. I can use any of them because I have purchased the PCTO (Personal Car Tuning Option). I'm particularly curious about the injector offsets because personally, I think they're of relatively minor importance, and involve a number of unknowns which cause a lot of tail chasing. Unless a vehicle is properly instrumented, we don't REALLY know true voltage at the injectors and at the fuel pump, nor do we know actual fuel rail pressure.

[redhardsupra]

so gear up! fuel pressure sensor writeup been done long time ago by TAQ, tested on himself, as well as EFILive's own Tordne, and I think BeerC5 done it too. Voltage at the pump can be easily measured, I'm not sure how different can it be at the injectors themselves.

if you think the injector characteristcs are of minor importance, i'd really like you to experience a perfectly sane STS car that does 9.x AFR on every deceleration, while it's very tame and obidient at any other condition.

[dfe1]

so gear up! fuel pressure sensor writeup been done long time ago by TAQ, tested on himself, as well as EFILive's own Tordne, and I think BeerC5 done it too. Voltage at the pump can be easily measured, I'm not sure how different can it be at the injectors themselves.

if you think the injector characteristics are of minor importance, i'd really like you to experience a perfectly sane STS car that does 9.x AFR on every deceleration, while it's very tame and obedient at any other condition.
I don't think injector characteristics are of minor importance, I think the variance in injector performance is negligible with a 1/2-volt change in voltage (provided you're not at voltage threshold) and with a properly functioning alternator and a battery in reasonably good condition, voltage variations will be transient. If you have to worry about injector performance at less than 12 volts, you have more serious problems to resolve. I'm not trying to discredit anyone, but I'm skeptical about this issue because I've never seen convincing documentation either about the process (hence my remarks about pressure and voltage) or the resulting benefits. We may now have the opportunity to correct that.

[hquick]

Yep...you know I'm willing Marcin.
I however need to get myself a fuel pressure sender so as I can log pressure at the rails as well as I want to replace my reg....as I don't fully trust the one I have.

[dfe1]

I logged battery volts versus rpm versus manifold mressure on the drive to work this morning. Most of the log is steady state cruise with a few normal accels and one WOT accel. Voltage varied more than I expected, but lowest was 13.7 volts, highest was 14.3 for a maximum variance of .6 volts. As soon as I get a fuel pressure sensor wired up, I'll move on to the next test stage.

[azzhauler]

Something I've been trying lately...


IFR Table {B4001}: Based on what you believe to be true about your injectors, you should use the IFR spreadsheet (http://www.marcintology.com/tuning/injectors.xls) RedHardSupra made available on his website (or a similar one) to initially set this table. Then using the reciprical of your BEN factor for your WBO2 along with the MANVAC pid, you'll correct this table. Remember, raising values lean out AFRs and reducing values richen AFRs in this table. This will become an important constant that you will base the rest of your tune on.
Sorry, I stole your format TAQ 'cuz I'm lazy these days. :)

For this part are you supposed to force OL, or stay in CL?

[SSpdDmon]

For this part are you supposed to force OL, or stay in CL?
That assumes you put B0120 down to something low like 100 rpm. And yes, you still force open loop with that method, which means setting op. temps to 14.63 and setting PE where you want it. This simulates closed loop. If you need PE to come on sooner, adjust the PE Enable table by lowering the TP% to nothing greater than 35~40%.

[Aint Skeered]

by tuning this way, do you leave the VE table alone? just play with injector flow rate is How my car ws tuned by a professional tuner and when I posted it on here last year when I first bought EFI live , everyone told me to start fresh and get away from the injector flow rate tune. I have to say, It worked pretty well as for WOT .

Does Ve Table play a roll still with this method?

[SSpdDmon]

by tuning this way, do you leave the VE table alone? just play with injector flow rate is How my car ws tuned by a professional tuner and when I posted it on here last year when I first bought EFI live , everyone told me to start fresh and get away from the injector flow rate tune. I have to say, It worked pretty well as for WOT .

Does Ve Table play a roll still with this method?
This process simply reverses the order of tuning and leaves the MAF curve stock since it should still have it's screen.

The idea is, drop the B0120 so you're in MAF only mode and tweak the IFR until you end up with an accurate representation of your IFR table. When you're done, it should be fairly linear. If not, there may be other injector tables that are in need of adjustment.

Next, you go speed density like normal (kill the MAF with Fail Frequency). Using your new IFR table, dial in the VE table. Once you're done, you should be able to re-enable the MAF, restore B0120 to stock or there abouts, and not have your fuel trims sky rocket like everyone always does.

Why do it this way? Personally, I'd much rather adjust the handful of IFR cells rather than the 84 MAF cells. Plus, I find it hard to believe that a cam & heads can drastically alter the MAF cal. You put the stock lid and bellow in and you'll still have to adjust the MAF curve with the other way. That to me says something is fishy and something is being fudged. So, fudge the MAF or the IFR??? I say fudge the IFR. Too many other tables rely on what the MAF reports (timing, trans pressures, etc.). That should stay stock IMO. :)

[405HP_Z06]

This process simply reverses the order of tuning and leaves the MAF curve stock since it should still have it's screen.

The idea is, drop the B0120 so you're in MAF only mode and tweak the IFR until you end up with an accurate representation of your IFR table. When you're done, it should be fairly linear. If not, there may be other injector tables that are in need of adjustment.

Next, you go speed density like normal (kill the MAF with Fail Frequency). Using your new IFR table, dial in the VE table. Once you're done, you should be able to re-enable the MAF, restore B0120 to stock or there abouts, and not have your fuel trims sky rocket like everyone always does.

Why do it this way? Personally, I'd much rather adjust the handful of IFR cells rather than the 84 MAF cells. Plus, I find it hard to believe that a cam & heads can drastically alter the MAF cal. You put the stock lid and bellow in and you'll still have to adjust the MAF curve with the other way. That to me says something is fishy and something is being fudged. So, fudge the MAF or the IFR??? I say fudge the IFR. Too many other tables rely on what the MAF reports (timing, trans pressures, etc.). That should stay stock IMO. :)

Have you tried this method with an complete aftermarket air intake and LS7 style MAF meter?

[redhardsupra]

SSpdDmon, let me get this straight: you entire argument about the superiority of the IFR fudging method over others is that it's simpler?
MAF isnt really 84 cells, it's more like 4 parameters describing the polynomial that creates the curve. IFR however is usually a lot more nonlinear than that, as you have voltage dropping affecting fuel pump output (a nonlinear relationship by itself), affecting the rail pressure, and then there's another nonlinear dependency of pressure delta vs IFR... if your argument is purely from simplicity, MAF wins by a long shot.

[SSpdDmon]

Have you tried this method with an complete aftermarket air intake and LS7 style MAF meter?
Only on my LS1s.

SSpdDmon, let me get this straight: you entire argument about the superiority of the IFR fudging method over others is that it's simpler?
MAF isnt really 84 cells, it's more like 4 parameters describing the polynomial that creates the curve. IFR however is usually a lot more nonlinear than that, as you have voltage dropping affecting fuel pump output (a nonlinear relationship by itself), affecting the rail pressure, and then there's another nonlinear dependency of pressure delta vs IFR... if your argument is purely from simplicity, MAF wins by a long shot.
I beg to differ. With the stock MAF curve, you'll see your voltage drop in your IFR because it won't be linear near 0kPa of manvac. If you have a car with a fresh h/c swap and start it up, it won't idle very well at all. A minor change to the base timing and changing B0120 - it idles right away. If that's not simple, I don't know what is. Trying to adjust 84 MAF cells via BENs vs 16 IFR cells, I pick 16. Also, as mentioned above, think of the effects of changing the MAF curve on things like your timing table. You essentially shift the table to the left by increasing the MAF. Stock curve may show .8 grams/cyl and adjusted curve .88 grams/cyl - you've now pushed the high/low timing lookup to a lesser value. Don't the A4 cars also use MAF readings??? I don't believe a 15~20% change in the MAF curve is right by any means. But, that's my choice to believe that...and I'm not here to dis-credit anything. Just saying this is another approach I took to skin the cat.

[TAQuickness]

$0.02

I like the creativity of SSpdDmon's approach and the fact he has consistent results with this method. I don't know that it will change my ways*, but do think it warrants a comparitive test drive.

* This is largly in part to the MAF not being able to compensate for changes in the induction plumbing. Given the installation environment, the MAF is not nearly as accurate as it is consistent.

[jfpilla]

SSpdDmon,
I do respect your right to tune as you see fit, so I'm not trying to change your mind, just want to share my observations.
I don't see a voltage drop when I scan WOT into an IPW voltage table.
I like the extra resolution of tuning the MAF and I see other parameters logged showing closer trims. The MAF is really not hard to tune and you need to tune upper frequencies to get WOT PE to match actual. Timing tables are useless and need retuning anyway. A4's use B5919 not the MAF for calculations except for 98's and 99's? If you have an optimal timing table it's used. It seems more fueling dependent tables are affected by IFR changes. I don't find that setting the MAF requires any other changes.
It seems that same injectors in different cars use the same tables?
My engine is an LS7 with longtubes and cold air. It's otherwise stock. The IFR is stock LS7. Seems the right thing to do. The stock MAF table does not work.
Joe

[SSpdDmon]

SSpdDmon,
I do respect your right to tune as you see fit, so I'm not trying to change your mind, just want to share my observations.
I don't see a voltage drop when I scan WOT into an IPW voltage table.
I like the extra resolution of tuning the MAF and I see other parameters logged showing closer trims. The MAF is really not hard to tune and you need to tune upper frequencies to get WOT PE to match actual. Timing tables are useless and need retuning anyway. A4's use B5919 not the MAF for calculations except for 98's and 99's? If you have an optimal timing table it's used. It seems more fueling dependent tables are affected by IFR changes. I don't find that setting the MAF requires any other changes.
It seems that same injectors in different cars use the same tables?
My engine is an LS7 with longtubes and cold air. It's otherwise stock. The IFR is stock LS7. Seems the right thing to do. The stock MAF table does not work.
Joe
I agree - there's some good resolution to fine tuning the MAF to dial in fuel trims. What I'm trying to avoid is massive changes. I think if you're changing it more than 5% or so, something doesn't seem right. I'm merely suggesting you get the IFR dialed in so, for the most part, commanded=actual. Then, any fine tuning you need to do afterwards shouldn't require anything major.

Oh well...I'll keep experimenting. It's fun... :D

[TAQuickness]

Oh well...I'll keep experimenting. It's fun... :D

No doubt! I'm curious to see the results I can derive utilizing this methodology.

For someone starting from scratch (bone stock) that is planning a build of any sort, I can see a slight variation of this method providing the means to backcheck/verify calculated injector settings. I seem to recall Geoff @ thunder describing a similar method to derive injector settings.

[joecar]

Oh well...I'll keep experimenting. It's fun... :DAnd it's educational.

[redhardsupra]

no, if education was involved, his science would be better. i'm unsubscribing, some people are beyond help.

[SSpdDmon]

no, if education was involved, his science would be better. i'm unsubscribing, some people are beyond help.
Just working with what I've got...

I don't understand how people can be so one sided? Do you honestly believe that increasing a MAF table 20% is more right than decreasing the IFR table? If you want to talk science, I say they're both wrong. I'm not here to argue that and I'm not beyond gone. I just want to see what works, what works consistently, and what can be done to work consistently with a shorter lead time for tuning. That's the supply chain side of me coming out I guess...

[ItzNota]

Argh!!....I spent all that time reading thru this thread only to find everyone pissed off and stopped discussing this important issue.

great.

[joecar]

:cucumber:

Welcome ItzNota... :cheers:

[TAQuickness]

Welcome to the forum ItsNota.

[TFZ_Z06]

Argh!!....I spent all that time reading thru this thread only to find everyone pissed off and stopped discussing this important issue.

great.

I only joined this forum about a year ago. If the only fight is over tuning methods (thats going to be infinite), thats a good one. I like it when guys think they are right and go to war. At least the passion for tuning is there.

Its a good place to hang out. Welcome :cheers:

[ItzNota]

:grin:
:cucumber:

Welcome ItzNota... :cheers:


Welcome to the forum ItsNota.


I only joined this forum about a year ago. If the only fight is over tuning methods (thats going to be infinite), thats a good one. I like it when guys think they are right and go to war. At least the passion for tuning is there.

Its a good place to hang out. Welcome :cheers:

Thanks alot guys....I hope to learn more about tuning and make a few friends while I am here...

Thanks for the warm welcome!! :grin:

[redhardsupra]

maybe you could try to start a new thread instead of littering a sticky-quality thread tho?

[ItzNota]

maybe you could try to start a new thread instead of littering a sticky-quality thread tho?

you're right..you're absolutely right...sorry...I will do that.

[WS600]

Does anyone know if there is anyway to determine the injector flow rate short of pulling them out and having them bench tested?

[joecar]

See if you can read the part number on them, if it is recognizable then their flowrates may be published somewhere.

[WS600]

I looked can't tell easily. I'll pull one and hope there is a part number making the rest of this message irrelavant. I know there a blue top Ford SVO but when you look on-line they have several shades of blue. JFPilla and I determined a round about rate for them but we don't know exactly being that Ford and GM use different fuel pressures. So a ford 28lb is a GM something other pound.

Thanks, stupid I didn't just check.

[joecar]

Oh, those ones, there are about 4 different published flowrates for those...:doh2:

[mr.prick]

Look here Fuel Injector Flow Rates & Pictures (http://www.witchhunter.com/injectordata1.php4)

[WS600]

Sorry, been away for a while. Thanks for the link and all the advice everyone. I plan to start working on her again this week.:rockon:

[rumblebox]

ok call me blind, but i cant find the AutoVe tutorial.

[WeathermanShawn]

Here you go rumblebox..http://download.efilive.com/Tutorials/PDF/AutoVE Tuning Tutorial.pdf (http://download.efilive.com/Tutorials/PDF/AutoVE%20Tuning%20Tutorial.pdf)

Happy New Year to all from snowed-in Colorado!!!

[joecar]

It's also included in the V7 install, see C:\Program Files\EFILive\V7.5\Doc\Tutorials on your hard drive.

[Rich Z]

IFR Table {B4001}: Very important that you start here and get this table right. You should use the IFR spreadsheet (http://www.marcintology.com/tuning/injectors.xls) RedHardSupra made available on his website (or a similar one). This is the one known constant that you will base the rest of your tune on.


Aw nuts..... Here you go saying that this step is VERY IMPORTANT and the link to that IFR spreadsheet table is a dead link. It's not nice to tease us newbies........ :wallbash:

[TFZ_Z06]

Aw nuts..... Here you go saying that this step is VERY IMPORTANT and the link to that IFR spreadsheet table is a dead link. It's not nice to tease us newbies........ :wallbash:

just take the IFR data that is there now and make a proportional change based on your new injectors. Then adjust the
entire IFR table up/down until your STFT are close. This will get you very close if you use an inj style sim to what sin there stock.

[Rich Z]

just take the IFR data that is there now and make a proportional change based on your new injectors. Then adjust the
entire IFR table up/down until your STFT are close. This will get you very close if you use an inj style sim to what sin there stock.

Well, can you do it as simply as that when not only are there new injectors, but new intake manifold, new (427) engine, larger turbo housings on the STS turbos, and a new fuel system?

I'm just trying to figure out the current tune on my car and figure double checking what is there against what seems like SHOULD be there is a good way to try to figure this stuff out. The IFR table has to be wrong (it's a diagonal line instead of a flat line) with the mapped fuel pressure regulator I am using, or I am seriously confused about how that is supposed to work. So I would like to try to figure out what it SHOULD be.

I know my join date makes it look like I've been around here for a while, but such just is not the case. I registered when I purchased my copy of EFILive, and haven't touched it until just a week or three ago. So I'm a very raw newbie at this stuff. So right now I'm reading the hell out of this forum. And not planning to flash anything until I've got a good idea of what I am doing. Otherwise I would surely just make things worse. Not that the car is running bad now, but there does appear to be some rough edges that need to be taken care of.

Thanks.

[TFZ_Z06]

Well, can you do it as simply as that when not only are there new injectors, but new intake manifold, new (427) engine, larger turbo housings on the STS turbos, and a new fuel system?

I'm just trying to figure out the current tune on my car and figure double checking what is there against what seems like SHOULD be there is a good way to try to figure this stuff out. The IFR table has to be wrong (it's a diagonal line instead of a flat line) with the mapped fuel pressure regulator I am using, or I am seriously confused about how that is supposed to work. So I would like to try to figure out what it SHOULD be.

I know my join date makes it look like I've been around here for a while, but such just is not the case. I registered when I purchased my copy of EFILive, and haven't touched it until just a week or three ago. So I'm a very raw newbie at this stuff. So right now I'm reading the hell out of this forum. And not planning to flash anything until I've got a good idea of what I am doing. Otherwise I would surely just make things worse. Not that the car is running bad now, but there does appear to be some rough edges that need to be taken care of.

Thanks.

A new intake manifold won't change idle vacuum or idle airflow, the fuel system should be coming in at the same PSI as the old one, a 427 idles very close to the same airflow as a 346 (my 12:1 416 does), proportionally more, and unless you stand on it the boost won't affect idle.

IF that turbo is low boost, MAYBE you can keep the MAF. If you PEG that meter and get error codes,
you will have to go to COS5. COS5 is designed to tune boosted apps to 3 BAR. Check it out under custom operating systems. In my sig, you will see that I run it on my car and I have provided a stock file.

You are obviously correct to be careful w/that monster and I certainly respect that.

I would consider tweaking injectors rates to fit idle using STFTs (0 to slightly negative; clear fuel trims then adj IFR), then for top end you can make sure either your MAF is tuned to the expected AFR (preferably to AFR expected in the PE vs RPM table) or done via COS5 boost table, both with a wideband. That will get you very close.

Easier said than done! Good luck. Lots of good info on the site.

[Dirktdolman]

Does anyone have a current location to find the IFR Spreadsheet? The one I downloaded from post 1 is blank.

[Gelf VXR]

This one?

[Dirktdolman]

It is a different title but I hope it is the same.

THANK YOU

[Gelf VXR]

I think it is

[Gelf VXR]

[emoji2]

[Dirktdolman]

OK just checking if I have done this correctly

I found this

http://i951.photobucket.com/albums/ad351/Daring1234/delphi%20Injector%2025317628_zpsl4jxrllj.jpg (http://s951.photobucket.com/user/Daring1234/media/delphi%20Injector%2025317628_zpsl4jxrllj.jpg.html)

I took that info and put it into WitchHunter converter page to convert the 220 cc/min to 21 lbs/hr

http://i951.photobucket.com/albums/ad351/Daring1234/IFR%20Convertion_zpsakxkgpwe.jpg (http://s951.photobucket.com/user/Daring1234/media/IFR%20Convertion_zpsakxkgpwe.jpg.html)

Then I took the data from the first two pictures and placed it into the Injector flow rate calculator.

http://i951.photobucket.com/albums/ad351/Daring1234/IFR%20spread%20sheet_zpsmdnuxede.jpg (http://s951.photobucket.com/user/Daring1234/media/IFR%20spread%20sheet_zpsmdnuxede.jpg.html)

My concern comes when I compare the results of the calculator to my tune file.

http://i951.photobucket.com/albums/ad351/Daring1234/IFR%20Tune_zpsrbw4atkp.jpg (http://s951.photobucket.com/user/Daring1234/media/IFR%20Tune_zpsrbw4atkp.jpg.html)

Are they supposed to be that different? I noticed on the calculator the numbers increase with vacuum but the tune does not.

[joecar]

Dirktdolman,

Does your FPR have a MAP reference (i.e. air hose connecting FPR to intake manifold)...?

Did you measure rail pressure (with MAP reference hose disconnected), is it 43.5 psi...?

Do your injectors flow 21 lb/hr at 43.5 psi (3 bar)...?

[joecar]

IFR is flat for MAP-referenced FPR.
IFR is sloped for un-referenced FPR.

[Dirktdolman]

Dirktdolman,

Does your FPR have a MAP reference (i.e. air hose connecting FPR to intake manifold)...?
YES

Did you measure rail pressure (with MAP reference hose disconnected), is it 43.5 psi...?
I have not. Will RPM change this pressure (more fuel being used)?

Do your injectors flow 21 lb/hr at 43.5 psi (3 bar)...?
I am only going by what I have found on Witchhunter and other site about the OEM injectors I have.

[joecar]

Does your FPR have a MAP reference (i.e. air hose connecting FPR to intake manifold)...?
YES
Ok, so your IFR will be flat (as you saw in your tune file).


Did you measure rail pressure (with MAP reference hose disconnected), is it 43.5 psi...?
I have not. Will RPM change this pressure (more fuel being used)?
The FPR regulates rail pressure, so rail pressure will not be influenced by RPM changes...

if FPR was un-referenced, then rail pressure would be constant (+/- 1 psi is acceptable);
if FPR is MAP-referenced, then FPR pressure equals FPR base pressure (contant) plus MAP...
i.e. rail pressure follows MAP.

( note: to measure rail pressure, temporarily disconnect the FPR reference hose, and measure the rail pressure. )


Do your injectors flow 21 lb/hr at 43.5 psi (3 bar)...?
I am only going by what I have found on Witchhunter and other site about the OEM injectors I have.
We need to know if they are rated at 43.5 psi or at some other pressure.

[joecar]

If your rail pressure measures 58 psi (say)...

and if the injectors are rated at 43.5 psi...

then you have to scale the flowrate by multiplying it by sqrt(58/43.5)... (the spreadsheet does this).

[Dirktdolman]

Based on what I have found on the net about this OEM numbered injector it rated 220 cc at 3 bar (21 lb/hr at 43.5 psi). I just check and my pressure with the vacuum line to the FPR disconnected is 53 PSI.

This is my new calculation

http://i951.photobucket.com/albums/ad351/Daring1234/Injector%20flow%20rate%20calculator_zps3zfooscn.jp g (http://s951.photobucket.com/user/Daring1234/media/Injector%20flow%20rate%20calculator_zps3zfooscn.jp g.html)

[joecar]

You measured 53 psi (it should be 58 psi)...? What vehicle do you have...?

[Dirktdolman]

03 2500 HD 6.0l New pump and FPR. Maybe my gauge is bad. It is about 20 yrs old

[joecar]

Is that a GMC Sierra or a Chevrolet Silverado, and which platform (C or K)...?

[Dirktdolman]

03 Chevrolet Silverado K2500 HD 6.0L Automatic 4X4

[joecar]

The service manual give these specs (for key-on engine-off several times):

55-62 psi VIN: V, T, U

48-54 psi VIN: Z

VIN = engine code in VIN (8th letter/digit).

[Dirktdolman]

I have a Vin: U and I just ran the key on engine off pressure test and it came back with 48 PSI.

I put a new Delphi Fuel Pump (FG0053), Napa Fuel Pressure Regulator (2-19782) and fuel pump relay on 24 Nov 2014. I would have put a new filter in at the same time but the one in there was only about 6 months old.

I did some research on Napa's website about the Delphi pump. Napa site says fuel Pump Pressure rating: 425 kPa. I converted this to 61.64103865 psi.

So something is wrong. Weak pump, weak FPR or plugged filter. I will replace the filter tomorrow and re-run the test.

[statesman]

What part number is on the injectors?

[Dirktdolman]

25317628

[statesman]

It'll be a Rochester.... 22.1lb @ 3bar.

[Dirktdolman]

According to Witchhunter.com it is a Delphi
http://www.witchhunter.com/injectordata1.php
http://www.witchhunter.com/flowdatapix/dl25317628.jpg

[joecar]

I have a Vin: U and I just ran the key on engine off pressure test and it came back with 48 PSI.

...You have to cycle the key several times.

[Dirktdolman]

I cycled the key probably 5 or 6 time

[joecar]

Is your FPR manifold referenced...?

[Dirktdolman]

Yes

[joecar]

FPR may have a problem... when you remove the reference hose, do you see/smell fuel in the end of the hose...?

[Dirktdolman]

No smell but I did re run the both test (Key-on/Engine-off and running with the reference tube removed). Both tests had the same results 54 psi. I wonder if they gave me the wrong FPR.

[Dirktdolman]

The service manual give these specs (for key-on engine-off several times):

55-62 psi VIN: V, T, U

48-54 psi VIN: Z

VIN = engine code in VIN (8th letter/digit).

I went down to my local parts store and borrowed their pressure tester. The Key-on/Engine-Off and the Engine-on (run) with the reference hose disconnected resulted in the same pressure of 56-58. During the run test the needle shakes back and forth.

[400ss]

with the engine RUNING, disconnect the reference hose... it should be in 58. if it is in 56 is ok, but it should be steady, do some WOT, and fuel pressure should stay in the same range , if you have a bad fuel pump it will loose pressure in WOTS.