IFR Table Query

[V8NHH]

Hi All
Modified car now running higher boost and new bigger injectors (60lb) I have been comparing stock to modified tunes that was done by shop and trying to understand some points, I cant understand why my new IFR table is flat to 400 Kpa then curves where original was a curve from start, have enclosed pic of both any help to understand this would be great.
I was under impression that if using bigger injectors they should still have curved operating profile?
1857018571

[joecar]

400kPa is the pressure difference across each innector at WOT, while 480 kPa is the pressure difference at maximum vacuum; if you had 1-bar boost then pressure difference is 300 kPa; so if you do not run with boost then IFR axis below 400 kPa is never used.

[V8NHH]

400kPa is the pressure difference across each innector at WOT, while 480 kPa is the pressure difference at maximum vacuum; if you had 1-bar boost then pressure difference is 300 kPa; so if you do not run with boost then IFR axis below 400 kPa is never used.

Yep lost me there!! (Confused)
I'm running 13.5 - 14psi max boost
What I think you saying is basically up to 400kpa not used in table.
I spend a lot of time not in boost as cruising on part /small throttle openings max 60 kpa on gauge in EDI unit.(my PE set for 95kpa)
Was thinking if IFR was curved then I would be using less fuel at lower end of table

[joecar]

Below 400kPa is for boost.

14.7 psi is 1-bar (100 kPa)

400 kPa is rail pressure, subtract boost from this.

Question: is your FPR manifold referenced or is it un-referenced...?

[joecar]

If IFR does not correctly model your injectors then fueling will be incorrect, and trims will have to correct it in CL, and in OL there is no trimming/correction.

If FPR is un-referenced then IFR is sloped (with sqaureroot pressure).

If FPR is manifold referenced then IFR is flat.

[V8NHH]

Yep that's where confused, factory tune was sloped. Car supercharged as standard (basically a four door ZL1 as stock tunes identical for both e67 LSA, T43 A6 6l90e)
Now more boost and more injector I don't believe should be seeing massive differences apart from air flows and fueling??

PM me please

[joecar]

Does your FPR have a boost/vacuum refence hose...?

[V8NHH]

Does your FPR have a boost/vacuum refence hose...?


Dunno believe fpr in tank with pump aka Zl1/Ctsv, stock tunes on these for LSA are identical in repository.
Tune is referenced gs/sec so I assume pump pressure controlled by ECM dependant on Readings from MAF selecting either 350,415,450kpa fuel pressure.

[joecar]

I'm locating a ZL1/CTSV tune to look at more closely... if vehicle is fitted with FPDM module then FPR still regulates rail pressure. If FPR is in tank then it is unreferenced.

[V8NHH]

18642
18643

Believe FPDM module no expert though!!
Couple of stock tunes

[joecar]

Thanks, I'll study the injector tables in those tunes.

[V8NHH]

PM Sent