Injector Base Pulsewidth

[5.7ute]

Just a quick question guys. Does the pid IBPWx include the calculated offsets & small pulse adders?
Cheers Mick

[mr.prick]

IBPWx is the actual PW, with offsets included.
Logging IBPWx against B4005, they should match very closely.

IIRC the offsets are an added value to the Minimum and Default pulse widths.

[joecar]

Yes, my understanding is that it is the final pw.

[5.7ute]

Thanks Guys. Wouldnt linking B4005 to the final pulsewidth pid make it incorrect, especially around the 1.8ms area. For instance in a stock Holden tune a 1.763ms pulsewidth has a small pulse adder of 0.075988. This gives a final pulsewidth of 1.838ms which will be in a different cell.
I think we may need to link B4005 to a calc.pid to narrow down those idle issues. Especially for large injectors.

[mr.prick]

When I have logged IBPW against B4005
the logged data matches closely with the rows.

I had my min PW set at 0.1ms and could not get below 1.6ms
even with the small pulse offsets negative.
This led me to believe that the injector I was using was
for some reason not allowing the pulse width below 1.6ms
and made low MAP/MANVAC areas inconsistent and a little rich.

I would like to know if GM makes they're own offsets or the injector manufacturer sets them.

[5.7ute]

I dont doubt it would match closely. The problem I envision is the way it is linked.
Since IPW is (Airmass/AFR )/IFR
IBPW = IPW + {B3701} + {B4005} unless IPW is less than {B4003} then we have
IBPW = {B4004} + {B3701} + {B4005}
From this I believe we need to link the modifier tables to IPW not IBPW. Problem being the IFR table is rather lacking in resolution for a non manifold referenced fuel pressure regulator to calculate IPW with a pid.
I could also be barking at shadows

[mr.prick]

Did you mean each injectors PW separately?

I have modded the cal.link for B4005 to track a calc.pid from IBPW1 and IBPW2,
to see if I could adjust the offsets with another calc.pid from the difference.
What is it normally?

[5.7ute]

It is normally either IBPW1 or IBPW2 which from this thread is the final pulsewidth calculation sent to the injector.
The B4005 table is a modifier which is added to the fuelmass calculation to give us the IBPW value. So we are linking a final value to a table that has derived that value, making it incorrect in the smaller pulsewidths.
For instance we have 14.63 grams of air in the cylinder. Divide that by our AFR of 14.63:1 gives us 1 gram of fuel needed.
Divide that by our IFR to give us the IPW necessary to inject that amount of fuel. To keep the example easy lets say 10ms.
Then if necessary small pulse adjust is added, again for simplicity add 1ms, and the same for our voltage offset gives a total of 12ms.
This will link as 12ms in the tune tool when it actually used the value of 10ms to calculate the final IBPW.

[5.7ute]

Thanks to a log from Hquick I have been looking into this a bit deeper. Howard uses a manifold referenced FPR so it made the pid easy to write.
One thing that I did notice is the pid GM.INJFLOW does not match his IFR table. Any ideas Ross or Paul?
Anyway, the difference between a calculated IPW from airmass per cylinder & the IBPWx pids seems to correlate roughly with the voltage offset. There is a slight difference though which may be due to other tables we cant see. I will have to look deeper.

[mr.prick]

Could you post the pids.txt you are using for this, please.