Rising Rate Reg (2:1) and IDC/IFR

[JezzaB]

Okay ive done a little reading and when resetting up a RR Reg you dont factor into boost at all you just setup the IFRs as per NA. And the AutoVE corrects the WOT AFRs

BUT What happens with your IDC though? If you are getting more fuel pressure on boost and the pcm doesnt know what pressure it is on boost wont your IDC be calculated wrong?

Im trying to get a little more out of my 42lb injectors as the IDC is a bit high. I may be way off track here but Id though I'd ask as there as always a wealth of info and people here.

Just curious as to how it works

Thanks
Jez

[Delco]

Okay ive done a little reading and when resetting up a RR Reg you dont factor into boost at all you just setup the IFRs as per NA. And the AutoVE corrects the WOT AFRs

BUT What happens with your IDC though? If you are getting more fuel pressure on boost and the pcm doesnt know what pressure it is on boost wont your IDC be calculated wrong?

Im trying to get a little more out of my 42lb injectors as the IDC is a bit high. I may be way off track here but Id though I'd ask as there as always a wealth of info and people here.

Just curious as to how it works

Thanks
Jez

You compensate with the boost VE table , since the VE is referenced to boost.

[SSpdDmon]

How does this affect IDC???

The equation shows IDC=(IPW*RPM)/1200. If you know the pulse width and RPM, you should be able to calculate IDC.

[joecar]

The PCM uses the IFR cell at MANVAC==0 to calculate IPW, and then IDC is calculated as SSpdDmon said in post #3.

Now, if you had a manifold referenced FPR, the IFR table would be flat (because the FPR now alters pressure such that pressure delta across any injector is constant as MAP varies)... is this your RR regulator...?

i.e. if you're installing a manifold referenced regulator (air hose connects manifold to FPR), you have to recalculate the IFR table based on the FPR pressure with the hose disconnected (i.e. at BARO)... and the IFR table would be flat horizontal all across.

[johnv]

THe IFR table is not set up as NA, with a rising rate FPR if vacume/boost referenced.

[JezzaB]

The PCM uses the IFR cell at MANVAC==0 to calculate IPW, and then IDC is calculated as SSpdDmon said in post #3.

Now, if you had a manifold referenced FPR, the IFR table would be flat (because the FPR now alters pressure such that pressure delta across any injector is constant as MAP varies)... is this your RR regulator...?

i.e. if you're installing a manifold referenced regulator (air hose connects manifold to FPR), you have to recalculate the IFR table based on the FPR pressure with the hose disconnected (i.e. at BARO)... and the IFR table would be flat horizontal all across.

Yup its a manifold referenced FPR. So to dial those tables in I would remove the hose to RR FPR (to simulate baro) and check the fuel pressure.

Then the pressure at baro is going to be used to calculate the IPW and inturn the IDC (which should drop down as im going to have a higher pressure than stock now @ 0 Manfold Vaccum)

So how do I use the pressure I just recorded to fill in the tables? Sorry, I know how to swap injectors and punch the figures into that snazzy redhardsupra excel spread sheet but the diff reg has thrown me out a bit.

The reg instructions say to install it and dial in the idle pressure to 58psi and you are done (on that side of things anyway).

Thanks for your patients and help. I like to understand what im doing when I do it so I can learn from it.

Jez

[joecar]

From this his thread: showthread.php?t=4821

Examples:

An SVO 42 lb/hr injector is rated to flow 42 lb/hr at fuel pressure 43.5 psi across the injector...
so, by definitions (see post #1):
R0=42 lb/hr
P0=43.5 psi

...

Example 2 (MAP-referenced regulator):

Suppose, with reference hose removed, measured fuel rail pressure is 58 psi (gauge pressure)... this is FP + BARO
so, from post #1:

IFR
= R0 * sqrt((FP + BARO) / P0)
= 42 * sqrt((58) / 43.5)
= 48.497 lb/hr
= 6.111 g/s

IFR is flat horizontal constant regardless of MANVAC.

You remove the reference hose while engine is running, measure the rail pressure, compute the flow rate using the measured rail pressure and injector ratings, enter this value in all cells of the IFR table...

and remember to reconnect the reference hose.

[JezzaB]

From this his thread: showthread.php?t=4821


You remove the reference hose while engine is running, measure the rail pressure, compute the flow rate using the measured rail pressure and injector ratings, enter this value in all cells of the IFR table...

and remember to reconnect the reference hose.

Thank you very much! Appreciate the help.

Jez