Please explain Delta MAP Kpa...

[Redline Motorsports]

Can someone please clarify the units used in the {B4001} for injector flow base?

How are the values derived that make up the row values in that table?

I also want to know if the E38.INJPDELTA_DMA pid is active and can be logged. Why are the values so large?

Howard

[Bruce Melton]

Howard,
We are on the same page, once again. Trying to adapt a E67 PCM/tune to run a LS7 with 40# stock LS7 injectors so same question-

[jfpilla]

OK, I'll guess that the units are MAP grams/second. The same as in B1210. Take a look at an LS1 file, table C2911. The units are the same and are defined. It seems they changed from MANVAC to MAP.

[Redline Motorsports]

I guess when you look at that table and see the -Kpa values it doesn't make sense as when do you see -Kpa's? Is this boost pressure?

When they state "delta", are they referring to a "change" in MAP pressure?

Still not gettin' it!

Howard

[dc_justin]

I guess when you look at that table and see the -Kpa values it doesn't make sense as when do you see -Kpa's? Is this boost pressure?

When they state "delta", are they referring to a "change" in MAP pressure?

Still not gettin' it!

Howard

Instead of referencing manvac such as the Gen-IIIs, these define fuel flow on the differential fuel pressure, which is what this table defines. On a 4 bar fuel system, 400kPa would be approx. WOT, 500kPa absolute vacuum. The question is, where does the ECM define what the static fuel pressure is? There's no fuel pressure sensor from the factory, is there?

[jfpilla]

I guess when you look at that table and see the -Kpa values it doesn't make sense as when do you see -Kpa's? Is this boost pressure?

When they state "delta", are they referring to a "change" in MAP pressure?

Still not gettin' it!

Howard

Howard,
I don't get your first question.
question 2: I read the table as a change in MAP measured in gps. MAP and MANVAC(used in LS1 IFR table)are essentially opposites. When you look at a log they add up to around 100.
Am i understanding your question?
Joe
Joe

[dc_justin]

Howard,
I don't get your first question.
question 2: I read the table as a change in MAP measured in gps. MAP and MANVAC(used in LS1 IFR table)are essentially opposites. When you look at a log they add up to around 100.
Am i understanding your question?
Joe
Joe

MAP can't be measured in gps. Two separate units entirely. gps can be calculated from MAP, RPM and a given VE definition, but otherwise the correlation doesn't exist.

[jfpilla]

MAP can't be measured in gps. Two separate units entirely. gps can be calculated from MAP, RPM and a given VE definition, but otherwise the correlation doesn't exist.

Thanks Justin. That was a dumb error. It may actually be a help to my Guess if it's a change in kpa.
Try this. If the PCM is referencing 100 kpa, then at 640(big change)the injectors could be told to decrease flow(higher IFB value)and at 128(small change)told to increase flow(lower IFB value).

Any takers?

[dc_justin]

It really looks like it only references the 400-500kPa portion of the log file though. One of the tune files I pulled up had static numbers from 400kPa and below and static again from 480 and above.

[jfpilla]

It really looks like it only references the 400-500kPa portion of the log file though. One of the tune files I pulled up had static numbers from 400kPa and below and static again from 480 and above.

It may be referencing the entire table but not changing the injector flow ouside those areas. Maybe they are getting ready for a blower? :grin:

In any case, what about Howard's question?

[redhardsupra]

zr1 (the supercharged one) has a dual fuel pressure operation. this is apparently what they were getting ready for with an absolute pressure scale. way cool!

[Redline Motorsports]

RHS,

Thats what I figured it was leading too. The FORDS use this kind of format but they have a pressure sensor to provide input to the PCM.

I guess for a NA situation, only half the table is utilized. Now the wonder is if we do a boosted application how can we get this info back into the PCM without a input sensor.

I also thought the LS9 was going to run with a E67 PCM....

Justin, have you logged that pid?

HT

[jfpilla]

Maybe this table is not being used right now?

[Redline Motorsports]

So 400 KPA is know equivalent to 0 KPA and 500 is equal to 100 KPA or WOT....

I see that parameter where its either MAP or vacuum......maybe that allows the other half of the table to be active.

[jfpilla]

Howard,
Good question to start this thread. Now we are all confused. :doh2:

MANVAC 0 kPa is 100% WOT. That's why the IFR values are lower at 0.
Joe

[Redline Motorsports]

Howard,
Good question to start this thread. Now we are all confused. :doh2:

MANVAC 0 kPa is 100% WOT. That's why the IFR values are lower at 0.
Joe

LOL!! I guess sitting on couch late at night after tuning you can't help but ponder in some of these evolutionary changes!

Seems like its like gauge pressure vs. absolute pressure.

The table goes from 128 to 640 KPA. This is obviously a value based off a absolute value. Question is how is this relative to gauge KPA that we see with the MAP sensor?

[jfpilla]

http://www.radyoruzgar.com/video.asp?v=I6EiNFiLhV0&search_query=corvette&page=1

ZR1 "flat out" video!

[joecar]

So 400 KPA is know equivalent to 0 KPA and 500 is equal to 100 KPA or WOT....

I see that parameter where its either MAP or vacuum......maybe that allows the other half of the table to be active.Hi Howard,

If that is absolute fuel rail pressure, then those numbers would be reversed like Joe said...

500 kPa would be at MAP = 0 kPa (full vacuum, MANVAC = 100 kPa)
400 kPa would be at MAP = 100 kPa (WOT, MANVAC = 0 kPa)

pressure difference across injector
= absolute rail pressure - MAP
= 500 kPa - 0 kPa = 500 kPa (the first case above)
= 500 kPa - 100 kPa = 400 kPa (the second case above)

i.e. the pressure regulator is set to 500 kPa absolute pressure which is simply 400 kPa gauge pressure.

(rememeber: 400 kPa is 58 psi)

[redhardsupra]

i'm not sure what is there to be confused about: with 400kpa being NA WOT, anything bigger than 400 is vacuum, and anything smaller than 400 is boost.

IFR is a function of MANVAC (or MAP and BARO, whichever you prefer), that's why it makes sense that the IFR table uses absolute pressure as the indepdent variable.

[dc_justin]

The next question is, where is 400kPa (gauge, 500kPa absolute) defined as the system's fuel pressure?

Edit: It's not. This things apparently have a fuel rail pressure sensor from the factory that explicitly tells the PCM what pressure it's getting.

[jfpilla]

[quote=redhardsupra;67478]i'm not sure what is there to be confused about:

That was a little joke. I guess it was a too subtle.:)

[joecar]

i'm not sure what is there to be confused about:

That was a little joke. I guess it was a too subtle.:)lol... took me a minute :doh2::grin:

[Redline Motorsports]

The next question is, where is 400kPa (gauge, 500kPa absolute) defined as the system's fuel pressure?

Thank you!

[redhardsupra]

if they're measuring fuel pressure, wouldnt there be a part number for some sort of sensor? do we have any gm dealers onboard to check it out? the big question is do they measure it, or just regulate it and hope it behaves as intended?

[Redline Motorsports]

Well its in the 07-08 ZO6 files and my whole point was if we are modifying this table, it only really needs to be adjusted from the halfway point as half the table is out the range of the NA ZO6....

[jfpilla]

Howard,
It would seem so. You know I calculated the IFR for the stock LS7 injectors for my 2003 vette. I doubt if it's a coincidence that the calculated values fit neatly into the 400 to 480 range. The only areas where the numbers change.
Joe

[Redline Motorsports]

So Joe, based upon that, we are only using 6-7 locations of the IFR table when making an injector change. What is all the other resolution for?

Even it is used for a supercharger.

[dc_justin]

So Joe, based upon that, we are only using 6-7 locations of the IFR table when making an injector change. What is all the other resolution for?

Even it is used for a supercharger.

I'd have to assume that the Gen-IV cars are the same as the trucks... which have a Fuel pressure sensor from the factory. Check the PID SAE.FRP. That table allows the PCM to maintain stable fueling in a wide variety of conditions, including undesirable ones such as a faulty fuel pump or regulator. Very cool stuff.

[Redline Motorsports]

I'd have to assume that the Gen-IV cars are the same as the trucks... which have a Fuel pressure sensor from the factory. Check the PID SAE.FRP. That table allows the PCM to maintain stable fueling in a wide variety of conditions, including undesirable ones such as a faulty fuel pump or regulator. Very cool stuff.

Justin,

Where is that sensor on the trucks? I have taken quite a few new ZO6's down to the frame and never have seen that sensor.

Howard

[dc_justin]

Justin,

Where is that sensor on the trucks? I have taken quite a few new ZO6's down to the frame and never have seen that sensor.

Howard

Couldn't tell you, just knew that it was accurately reporting. In the tank?

Justin

[Redline Motorsports]

Couldn't tell you, just knew that it was accurately reporting. In the tank?

Justin

I've had tanks out to install fuel systems and don't remember seeing anything. What data does that pid report??

[dc_justin]

I've had tanks out to install fuel systems and don't remember seeing anything. What data does that pid report??

On this particular truck, right around 43.5psig. Was fluctuating slightly, but pretty stable.

[jfpilla]

So Joe, based upon that, we are only using 6-7 locations of the IFR table when making an injector change. What is all the other resolution for?

No clue Howard and the values in B1210 follow the same pattern.
B1206 might be a reason for limiting IFB values, but I don't see anything that explains the outlying values.
While looking I noticed B4001 and B1210 are labeled MAP, but "injector parameters" offers a choice of MAP or VAC. My file has VAC selected.

[dc_justin]

On this particular truck, right around 43.5psig. Was fluctuating slightly, but pretty stable.

That was an 08 6.2L Sierra Denali. Checked an 07 2500HD with the LY6 6L engine. No pressure sensor on it.

[mr.prick]

Howard,
It would seem so. You know I calculated the IFR for the stock LS7 injectors for my 2003 vette. I doubt if it's a coincidence that the calculated values fit neatly into the 400 to 480 range. The only areas where the numbers change.
Joe

How did you do this?

[69camaro5speed]

so from what I get delta map psi is fuel pressure vs what injectors flow over fuel pressure change
I have a 2010 6.0 suburban motor 6.0 with l92 heads we make them 408strokes they have changed injectors 3 times from 07 to 2010 the 2010s from what i get here have around 55 lbs injectors.
I engine dyno test them befor they leave with a e38 sd tune I made to make sure every things ok I put the first 2010 on and its like 10 to 1 afr I get looking at b4001 it has 55 lbs injectors going off what it seems here I been trying to figure out how that table works for some time (posted while back )seems funny tune says its not flex fuel with that size injectors its over kill for stock great for me.Hear is stock tune

[joecar]

deltaMAP = pressure difference across injector = absolute rail pressure - MAP

note: absolute rail pressure = 500kPa absolute = 400kPa gauge (58psi gauge)

e.g.
deltaMAP=400kPa --> at WOT with NA
deltaMAP=440kPa --> cruise with OEM cam (40kPa vacuum)
deltaMAP=460kPa --> idle with OEM cam (60kPa vacuum)
deltaMAP=500kPa --> theoretical full vacuum (100kPa vacuum)

deltaMAP<400kPa --> boost (MAP > 100kPa)

[joecar]

so from what I get delta map psi is fuel pressure vs what injectors flow over fuel pressure change
...Almost, not quite...

Stock FPR is set constant to 58 psi (i.e. unreferenced returnless system), fuel pressure should not change... but pressure difference across injector changes as MAP changes...

flowrate is proportional to squareroot of pressure difference across injector,

so ECM has to account for changes in pressure difference across injector due to changes in MAP.

deltaMAP = pressure difference across injector = absolute rail pressure - MAP

e.g.
What happens to pressure difference across injector when MAP is:
40kPa...?
80kPa...?
100kPa (WOT)...?
(absolute rail pressure is 500kPa)

[joecar]

If you have a manifold-referenced FPR (i.e. with return line), then, the FPR will vary rail pressure (as MAP varies) to always keep pressure difference across injector constant...

in this case, the injector flow rate will be the same value regardless of MAP, and table B4001 will be flat static (same value all cells).

[69camaro5speed]

deltaMAP = pressure difference across injector = absolute rail pressure - MAP
ok I see what you are saying maybe lol It takes Into the fact that say 60 kpa its sucking on the injectors harder so they flow more. so if it uses 400 delta map psi as a rail pressure (58lbs )looks like the number to figure injector size thats in the motor.

I understand as vac.goes up the injectors will flow more.Its like a map pressure differance vs injector flow (how it changes injector flow)

but little confusing 400 kpa is 58 lbs. the fuel pressure is 58 lbs but it doesnt change its almost like its a fuel rail pressure table for the injectors

So if I get it 400 kpa is wot injector flow for say 100 kps map and say 460 kps would be high vac. so injectors will flow more say around 4lbs on this tune.
If it had boost then delta map would go down and injectors will flow less say under 400kpa like 350 kpa because you have boost pushing on injectors

ok hope my slopy typing hasnt killed you lol better with wrenchs thanks

[joecar]

Yes, correct, for an un-referenced FPR, injectors flow more when MAP is less than BARO (100 kPa at sea level), i.e. when vacuum is present.

Yes, injector flow vs injector pressure difference

injector pressure difference = absolute pressure at top - absolute pressure at bottom

The conversion is: 100 kPa == 14.5 psi == 1 bar

so 400 kPa == 58 psi == 4 bar: This is what you will measure with a gauge at the fuel rail.

Also note: 400 kPa gauge pressure == 500 kPa absolute pressure
(i.e. absolute pressure = gauge pressure + baro )

Yes, 460 kPa is 60 kPa vacuum, so injectors flow more.
Yes, 350 kPa is 50 kPa boost, so injectors flow less.

lol, I'm still here :)

[69camaro5speed]

Thanks I like when stuff adds up lol

[joecar]

Ok, pop-quiz:

What are the MAP values that corresponds to the deltaMAP values 460 kPa and 350 kPa...?

:)

[69camaro5speed]

guess i should log that pid

[joecar]

injector pressure difference = absolute pressure at top - absolute pressure at bottom

460 kPa = 500 kPa - MAP --> so MAP = 40 kPa (i.e. vacuum is 60 kPa)

350 kPa = 500 kPa - MAP --> so MAP = 150 kPa (i.e. boost is 50 kPa)

[joecar]

Why is absolute pressure at top = 500 kPa...?

Hints:
- what is the difference between absolute pressure and gauge pressure...?
- what is un-referenced (constant) rail pressure in psi or kPa...?

[joecar]

Thanks I like when stuff adds up lolYes, I like it too... :cheers:

When stuff doesn't add then there may be a problem.

[Naf]

I sort of understood, but i am lost here. I am tryin to Log the inijector flow base for my E-38 to see if i may repair the tune that way instead of going through the complicated map. What PIDs do i select, so i may log for this Map

I have had plenty of success with my older vehicles using this technique.

Looking forward to your reply

Naf

[joecar]

I thought the pid was E38.INJPDELTA.MAP, in addition to SAE.MAP.

[mr.prick]

My definition of Delta_MAP is the actual (not percentage) difference of
the current frames MAP value from the last.

#Units Low High Fmt Expression
#------- ---------- --------- -------- -------------------------------------------
psi -16 16 .0 "({SAE.MAP.psi})-value({SAE.MAP.psi},frame()-1)"
kPa -105 105 .0 "({SAE.MAP.kPa})-value({SAE.MAP.kPa},frame()-1)"

[joecar]

My definition of Delta_MAP is the actual (not percentage) difference of
the current frames MAP value from the last.

#Units Low High Fmt Expression
#------- ---------- --------- -------- -------------------------------------------
psi -16 16 .0 "({SAE.MAP.psi})-value({SAE.MAP.psi},frame()-1)"
kPa -105 105 .0 "({SAE.MAP.kPa})-value({SAE.MAP.kPa},frame()-1)"Hi Mike,

In this thread's context, DeltaMAP is the pressure difference across any one injector, as used by E38/E67 calibration files. :)

See next post.

[joecar]

absolute rail pressure = gauge rail pressure + BARO

MANVAC = BARO - MAP

DeltaMAP = absolute rail pressure - MAP = gauge rail pressure + MANVAC


gauge rail pressure is typically 400kPa (58psi).

[mowton]

deltaMAP = pressure difference across injector = absolute rail pressure - MAP

note: absolute rail pressure = 500kPa absolute = 400kPa gauge (58psi gauge)

e.g.
deltaMAP=400kPa --> at WOT with NA
deltaMAP=440kPa --> cruise with OEM cam (40kPa vacuum)
deltaMAP=460kPa --> idle with OEM cam (60kPa vacuum)
deltaMAP=500kPa --> theoretical full vacuum (100kPa vacuum)

deltaMAP<400kPa --> boost (MAP > 100kPa)

I know this is an old thread, but does this mean we only have to scale IFR to 500 (flat line 63.5 beyond) which with large injectors will provide more low level granularity for certain scaled tables like timing.

Thanks,

Ed M

[joecar]

Yes, only up to 500 kPa.

[izaks]

I know this is an old thread, but

Here are some results of testing Holden's fitted with the E38 (all at altitude KOEO 84-85 kpa)

If the car is not fitted with an FSCM, INJPDELTA will not record below 400 KPA (irrespective if NA or boosted)
If the car is fitted with an FSCM but switched off in the ECM, INJPDELTA will not record below 400 KPA (irrespective if NA or boosted)
If the car is fitted with an FSCM and is enabled, INJPDELTA will record less than 400 when boosted. The INJ PW also increases compared to FSCM switched off. (INJPDELTA now less than 400)
When in boost, INJPDELTA does not follow the calculation posted earlier. (still trying to understand why)
Some examples of logging


MAP
INJPDELTA_DMA


kPa
kPa


84
415.6


84
415.6


84
415.6


84
415.6


84
415.6


84
415.6


84
415.6













MAP
INJPDELTA_DMA


kPa
kPa




164
375


167
380


175
383


190
381


195
368


199
365


198
351


195
330


191
355


194
352


198
354

[joecar]

Good question... it seems the ECM has knowledge and/or control of the pressure produced by the FSCM, so the above math relationships are broken.

[izaks]

It makes some sense when you compare the injector flow base of non FSCM and FSCM equipped cars
FSCM cars have a fuel pressure sensor and the IFB caters for boost, which the non FSM do not

NON FSCM (flat line from 400) sq root
LABELS Injector Flow Base (Grams/Second)
Delta MAP kPa Value
128 5.337646
144 5.337646
160 5.337646
176 5.337646
192 5.337646
208 5.337646
224 5.337646
240 5.337646
256 5.337646
272 5.337646
288 5.337646
304 5.337646
320 5.337646
336 5.337646
352 5.337646
368 5.337646
384 5.337646
400 5.337646
416 5.478027
432 5.615112
448 5.748779
464 5.879394
480 6.007446
496 6.007446
512 6.007446
528 6.007446
544 6.007446
560 6.007446
576 6.007446
592 6.007446
608 6.007446
624 6.007446
640 6.007446

FSCM (slope)
LABELS Injector Flow Base (Grams/Second)
Delta MAP kPa Value
128 2.974609
148 3.198486
168 3.407959
188 3.604980
208 3.791992
228 3.969970
248 4.140625
268 4.304199
288 4.461914
308 4.614257
328 4.761718
348 4.904785
368 5.043701
388 5.178955
408 5.310790
428 5.439453
448 5.564941
468 5.687988
488 5.808105
508 5.926025
528 6.041503
548 6.154785
568 6.266113
588 6.375488
608 6.483154
628 6.588867
648 6.692870
668 6.795409
688 6.896484
708 6.995849
728 7.093993
748 7.190917
768 7.286376