Injector Pulse Width

[Cringer]

In the scanner, does the reported IPW number ignore:

• fuel injector characterization modifiers (vacuum, voltage, temp offset)
• fuel trims

My understanding is that the scanner IPW values reflect airflow into the engine, injector flow rate (at the current fuel pressure) and commanded AFR. So if you are running lean or rich at any given time IPW would not deviate.

Here is an example of what I am talking about: https://forum.hptuners.com/showthrea...l=1#post682824
Side note: what ever happened to HJTRBO?

[RDF1]

He logged in 3 days ago.

[ns158sl]

I guess I always thought it literally was the Pulsewidth. Which we know is all dependent on a slew of variables, but primarily Dynamic AF including trims along with EOIT and RPM.

[07GTS]

i believe its the end commanded PW after all variables, i have had an issue years ago with it flooding on startup because of some transient fuel table changes (bug fault i think), it commands over 200ms PW as soon as it fires that is shown so if it wasnt the applied end PM it should show normal PW and being a transient change it should be very minimal at startup

[verlon]

In the scanner, does the reported IPW number ignore:

• fuel injector characterization modifiers (vacuum, voltage, temp offset)
• fuel trims

My understanding is that the scanner IPW values reflect airflow into the engine, injector flow rate (at the current fuel pressure) and commanded AFR. So if you are running lean or rich at any given time IPW would not deviate.

Here is an example of what I am talking about: https://forum.hptuners.com/showthrea...l=1#post682824
Side note: what ever happened to HJTRBO?

Injector Puslewidth PIDs (12C3 and 12C4) reflects final IPW without injector offset.
It includes commanded AFR, IFR with all corrections, Transient fueling (wall wetting), POSD Eq Ratio multiplier, Fuel Trims and Short Pulse Adder.

[Cringer]

Injector Puslewidth PIDs (12C3 and 12C4) reflects final IPW without injector offset.
It includes commanded AFR, IFR with all corrections, Transient fueling (wall wetting), POSD Eq Ratio multiplier, Fuel Trims and Short Pulse Adder.

Thank you again Verlon!

Questions:

• What offset are you referring (tip temp)?
• What is the POSD Eq Ratio multiplier?
• As far as the transient though, that is where I have major questions...since you brought it up. If what you are saying is true, then [IPW] = [Main Pulse] + [Make Up Pulse]. Correct?

[verlon]

What offset are you referring (tip temp)?
What is the POSD Eq Ratio multiplier?

Offset is [ECM] 12303 + ( [ECM] 12308 or [ECM] 12309 )
POSD - Postcat Oxygen Sensor Diagnostic. Intrusive test for downstream O2 sensors.

As far as the transient though, that is where I have major questions...since you brought it up. If what you are saying is true, then [IPW] = [Main Pulse] + [Make Up Pulse]. Correct?

Yes and no.
IPW PIDs is an average for the bank.
Since Makeup Pulse is required IPW is changed enough during Main Pulse so what exactly IPW do you mean? At what moment?
At the moment of SOI this will be true : [Main Pulse] = [IPW] + [Offset]

[Cringer]

Offset is [ECM] 12303 + ( [ECM] 12308 or [ECM] 12309 )
POSD - Postcat Oxygen Sensor Diagnostic. Intrusive test for downstream O2 sensors.



Yes and no.
IPW PIDs is an average for the bank.
Since Makeup Pulse is required IPW is changed enough during Main Pulse so what exactly IPW do you mean? At what moment?
At the moment of SOI this will be true : [Main Pulse] = [IPW] + [Offset]

Thank you for the clarification.

One last question, over what time frame is the average determined? Is it two revolutions of the crank, that way each cylinder goes through one complete cycle?

[verlon]

One last question, over what time frame is the average determined? Is it two revolutions of the crank, that way each cylinder goes through one complete cycle?

Its just average of last calculated IPWs for all cylinders of the given bank.

[04silverado6.0]

I had wondered the same but always assumed it was total pw.

[Andrew Woodward]

i believe its the end commanded PW after all variables, i have had an issue years ago with it flooding on startup because of some transient fuel table changes (bug fault i think), it commands over 200ms PW as soon as it fires that is shown so if it wasn't the applied end PM it should show normal PW and being a transient change it should be very minimal at startup

Don't want to hijack this thread so you can PM me if preferred, but I wanted to ask you about that issue. I am having the same problem on a 2009 GXP with a Magi 2650. I had to make a lot of changes to this including some transients and VE manipulation to sure a boost/lean spike but I am also having a problem with a 300ms PW after startup. Seems to mainly happen right after a flash and a couple times that it was having that problem, if I got it started it seemed okay after that. I was also thinking it was a transient problem and I made a change yesterday that seemed to fix it but it's doing it again this morning.

Also it's not letting me post a file or log because the window that pops up appears to log me out after about 1 second.

[07GTS]

Don't want to hijack this thread so you can PM me if preferred, but I wanted to ask you about that issue. I am having the same problem on a 2009 GXP with a Magi 2650. I had to make a lot of changes to this including some transients and VE manipulation to sure a boost/lean spike but I am also having a problem with a 300ms PW after startup. Seems to mainly happen right after a flash and a couple times that it was having that problem, if I got it started it seemed okay after that. I was also thinking it was a transient problem and I made a change yesterday that seemed to fix it but it's doing it again this morning.

Also it's not letting me post a file or log because the window that pops up appears to log me out after about 1 second.

find a previous change that was good and put that back in or even factory settings, some have said its the ''gains'' are the cause but mine i never changed those, i think its a change that triggers it for some reason mine was in the impact or evap tables i think but never narrowed it down, i also had it in an e67 ecu making changes so it is e38 and e67 same issue by random transient settings causing it, another issue it caused in mine years ago was i could startup cold and it was fine but as engine heated up it gradually got richer and richer over 5-10 mins till it flooded the engine then turn off for 15 mins and startup ok then slowly richer till flood, when it happened on my new build it was fine on petrol but soon as i shifted to ethanol the flood on startup begun, very annoying but just change the transients back should fix it, make sure VVE/VE is good for the PD blower helps

[Cringer]

07GTS and Andrew Woodward: is the post cat O2 and cat tests disabled in your tunes?

[07GTS]

yes both disabled with the 4.8.7 editor back when it was normal to do

[07GTS]

flooding issue log

[Cringer]

Man that is crazy. 258ms IPW and 240% IDC!

Have you log the fuel pressure channel to see what happens?