IBPW {B4005} {B3701} correlation

Finally had some spare time to "prove" the make up of the GM.IBPW pid. What I did was fit the roadrunner, start the car & let it idle. While monitoring the GM.IBPW pid I increased the values in the {B3701} voltage/manvac table while in emulation mode & noted a corresponding increase in the GM.IBPW pid.
So from this we can ascertain that IBPW is contrived from a calculated value plus the offset.
Next I zeroed out the {B4005} short pulse adder table. While once again monitoring GM.IBPW I started adding a value of 1.0ms starting from 1.8ms & working my way up the table. While the GM.IBPW pid was reading 3.1ms at idle, populating the 2.6ms cell in {B4005} caused a surge in the IBPW. Showing that the {B4005} table also runs from the calculated value BEFORE the offset is added.
While I have been stating for a while that this is the case, I am glad I have finally proven to myself that this is correct.
Also note that any transient fuelling addition (wall wetting etc) is also part of the GM.IBPW pid & must be removed if trying to solve backwards for airmass.

Good work. http://smiliesftw.com/x/sherlock.gif

I know you've been talking about proving this for a while.
Your explanation makes it look easy why did this take so long? :music_whistling_1:

On a side not I've never noticed any changes in AFR with RTACS & {B4005}.
{B3701} is another story, in OL fueling can be controlled w/RATCS & BEN factor.

Now if only we could log PW w/o all the adders/offsets so we could build new offsets. :laugh:
I guess we could make a couple of lookup PIDs and spreadsheets. :sly:

I already use a calc.pid for the IPW without the offsets/adders.
CALC.IPW=(GM.DYNCYLAIR_DMA/GM.AFR/GM.INJFLOW)*1000
This I then link to B4005 in the cal_link.txt file.
I was trying to prove this all with calculations, but the noise in the scanner could only get it close. Not close enough to prove though.
Marcin had suggested the low tech approach a while ago, but I got sidetracked with some .cax files I was working on. Luckily I didnt have much on in the last few days & worked out exactly how I would go about it.
Since by default B4005 is linked to IBPW, RTACS will be raising the wrong cells to show a rise in the AFR. Also I found that it tends to "bounce" the IBPW. I will be looking deeper into the cause of this.
EDIT: I also have to look at whether B4005 is added to a default pulsewidth value, which I am sure it is.

Mick, good job researching this...:cheers:

Can {CALC.CYLAIR} be used in place of {GM.DYNCYLAIR_DMA}?

Is {GM.INJFLOW} derived from the IFR table {B4001}?
Can a calc_pid be used in place of it, something based off fuel pressure?

It would be nice to be able to log more PIDs w/the RR.
I wonder if it's possible to log directly from the RR. :gossip:
:blahblah:

Quote:

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Originally Posted by mr.prick

Can {CALC.CYLAIR} be used in place of {GM.DYNCYLAIR_DMA}?

Is {GM.INJFLOW} derived from the IFR table {B4001}?
Can a calc_pid be used in place of it, something based off fuel pressure?

It would be nice to be able to log more PIDs w/the RR.
I wonder if it's possible to log directly from the RR. :gossip:
:blahblah:

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Yes, {CALC.CYLAIR} can be used when using the maf, but only when you are over the dynair prediction value {B0120}. Otherwise there could be a small error if the values dont match.
As for the calc pid for injector flow related to fuel pressure it would not be usable, since you want to use the same values as the pcm is seeing. If however you were back solving airmass you would use this value & your wideband AFR to calculate it. (along with GM.IBPW- offsets)

Mick,

So would this be how we think the PCM is calculating IPW and IBPW:

Code:

---

IFR = lookup(B4001);

IPW = airmass / AFR / IFR * 1000;

if IPW < B9021 then
    IPW = B9021;

if IPW < B4003 then
    IPW = B4004;

if IPW < B4006 then
    IPW = IPW + B4005;

IBPW = IPW + B3701 + TF;

---

Did I get IPW and IBPW in the right places...?

See posts #6, #13: Injector-Base-Pulsewidth

Were there any other threads specifically on this topic, I'm trying to link them together...?

That's right Joe, apart from the IPW needing to be turned into ms.
We can also now expand to

IFR = lookup(B4001);

IPW = airmass / AFR / IFR *1000;

if IPW < B9021 then
IPW = B9021;

if IPW < B4003 then
IPW = B4004;

if IPW < B4006 then
IPW = IPW + B4005;

IBPW = IPW + B3701 + TF;

guys, cant you post this in form that people that dont remember every table number can read?

HaHaHa, I had a cheat sheet in front of me with table numbers & functions so I could follow it.
IFR = lookup(B4001);

IPW = airmass / AFR / IFR *1000;

if IPW < B9021(minimum transient pulsewidth) then
IPW = B9021;

if IPW < B4003(minimum pulsewidth) then
IPW = B4004(default pulsewidth);

if IPW < B4006(small pulse threshold) then
IPW = IPW + B4005(small pulse adder);

IBPW = IPW + B3701(voltage/manvac offset) + TF(transient fuelling modifiers);