What's up with my IFR?

[1098980405]

Here's the IFR table from my canned Whipple tune:



Labels 18.6 21.5 24.4 27.3 30.2 33.1 36.0 38.9 41.8 44.7 47.6 50.5 53.4 56.3 59.2 62.1 65.0 67.9 70.8 73.7 76.6 79.5 82.4 85.3 88.2 91.1 94.0 96.9 99.8 102.7 105.6 108.5 111.4
Flow Rate 46.99 46.99 46.99 46.99 46.99 46.99 46.99 46.99 46.99 46.99 46.99 46.99 46.99 46.99 46.99 46.99 47.99 49.00 49.99 52.00 52.00 52.00 52.00 52.00 52.00 52.00 52.00 52.00 52.00 52.00 52.00 52.00 52.00

The Whipple comes with bigger injectors and has an MSD BAP but does it make sense to have flow rate set constant as the pressure changes? The flow is the same (46.99) all the way down to 18.6 psi.

[mowton]

Pressure Delta is the difference between the Manifold Pressure and the Fuel Rail pressure. In a 58 PSI fuel system the fuel rail pressure would be 400 kPa or 4 Bar. As your manifold pressure changed, so would the Delta Pressure and the PCM would derive the IFR from that specific cell. So what you are seeing is injector data being populated only in the the more conventionally 1 Bar cells previously identified by 0- 80 kpa (or in the case of your posting in PSI, 62.1 - 73.7).

The table now allows for changes in Fuel Rail pressure and boost manifold pressures (i.e were getting ready for setups like the ZR1) to define the Injector Flow Rates. With the BAP, you would expect the IFR to be held constant as you increase the boost as you are increasing the Fuel Rail pressure as well as the Manifold pressure.

Ed M

[DSteck]

Fuel pressure won't go up. His factory fuel system is mechanically regulated at 58psi.

Whipple canned tunes are poor. I'd start from scratch and do your own.

[mowton]

[QUOTE=DSteck;316420]Fuel pressure won't go up. His factory fuel system is mechanically regulated at 58psi. QUOTE]

So the more accurate tutorial would be the BAP will just manage to maintain enough fuel pressure to stay within the regulated 58 based on more fuel flow demand at boost?



Ed M

[DSteck]

A BAP just pushes more voltage to the pump. The regulator bleeds it down to 58. If the pump can't keep up, pressure drops.

[mowton]

A BAP just pushes more voltage to the pump. The regulator bleeds it down to 58. If the pump can't keep up, pressure drops.

More voltage = more pressure (more fuel flow) to keep up with the 58 minimum during increased fuel demand.....boost.

Ed M

[DSteck]

...

That doesn't mean it actually maintains 58psi, and certainly doesn't increase it with boost. The voltage increase may be triggered by boost, but it doesn't make it act like a 1:1 system.

[edcmat-l1]

More voltage = more pressure (more fuel flow) to keep up with the 58 minimum during increased fuel demand.....boost.

Ed M

More fuel flow does not equal more pressure. The pressure is mechanically regulated. The flow is somewhat mechnically regulated, but the higher the voltage, the higher flow potential of the pump.

[IDRIVEAG8GT]

More voltage = more pressure (more fuel flow) to keep up with the 58 minimum during increased fuel demand.....boost.

Ed M

You mean 58 psi maximum.

[mowton]

Well I guess this hasn't been one of my better posts. having a tough time explaining what I think I know and have done

I understand the pressure will be regulated at 58 lbs and the pump has to keep up with the fuel flow requirement. If the PCM/injectors are demanding more fuel than the pump can keep up with, the pressure will drop (lean out). To compensate for this scenario you increase the voltage to the pump to increase its flow rate to maintain, at a minimum, a fuel rail pressure of 58 lbs.... and any more will be returned back to the tank. I'm not saying the pump will try and maintain the 58, only needs to increase flow rate to get to at least 58 to get the regulator to do it's thing.

I think that is what I have been trying to state....no?



Ed M

[V locity]

What about the IPR? Doesn't this vary with voltage...?

[1098980405]

Thanks for pointing out that it's the difference (delta). I thought that since the original MAP can't read boost there could be a part of the table that would flat line, but the fact is that it will just go off the table to the left and stay at that flow rate (in this case 47#). I'd think that'd make it way lean because it's expecting a much higher fuel flow than is reality.

My understanding of the fuel module is that it will PWM the voltage to the pump to regulate the desired pressure. The system can change the target pressure for many different conditions but on my E38 it's set to 58psi for almost everything. The BAP just makes more voltage available for the module so the pump will flow more with the same duty cycle. Without the BAP the most flow the pump will give is at 100% duty cycle which will be equal to battery voltage. With the BAP the flow will be increased because 100% duty will be over 17v.

I still think the IFR should slope similar to the stock tables, even with the BAP.

Does anyone know the size of the injectors in the Whipple kit?

Thanks for the help.

[1098980405]

I guess I should have pointed out the car is a 2010 Camaro with the L99. It's a returnless fuel system (now with an MSD BAP). I believe the pressure is electronically regulated, but I do think it's correct to say it has a high pressure mechanical relief.

[stan]

My kit came with 60 lb siemens but that was 2 years ago. Get a ZL1 Map and do it right. That table looks way off and should be curved.

[IDRIVEAG8GT]

I guess I should have pointed out the car is a 2010 Camaro with the L99. It's a returnless fuel system (now with an MSD BAP). I believe the pressure is electronically regulated, but I do think it's correct to say it has a high pressure mechanical relief.

Fuel pressure is set to static 58 psi through a mechanical regulator. The FPCM takes care of pump DC.

[IDRIVEAG8GT]

Well I guess this hasn't been one of my better posts. having a tough time explaining what I think I know and have done

I understand the pressure will be regulated at 58 lbs and the pump has to keep up with the fuel flow requirement. If the PCM/injectors are demanding more fuel than the pump can keep up with, the pressure will drop (lean out). To compensate for this scenario you increase the voltage to the pump to increase its flow rate to maintain, at a minimum, a fuel rail pressure of 58 lbs.... and any more will be returned back to the tank. I'm not saying the pump will try and maintain the 58, only needs to increase flow rate to get to at least 58 to get the regulator to do it's thing.

I think that is what I have been trying to state....no?



Ed M

Most FPCM's I've tested leave an 8psi variance on the table before throwing a MIL. Theoretically pressure is supposed to stay at 58 psi, so the FPCM actually bumps the fuel pressure around in .2psi increments until it finds the lowest voltage possible to supply to the pump while maintaining consistent rail pressure.

The FPCM unlike a BAP can't ramp up the fuel pump voltage to more than what is in the system, so if a fuel pump is operating with the FPCM at maximum duty cycle and measured rail pressure is below the 50 psi minimum, soon a MIL will be set.

A BAP is used to supply more fuel in a situation of high demand. It ramps voltage over what's in the system to flow more fuel under low pressure situations, or ramp up pressure in low flow demands. Both actively supply more fuel to the engine. Once the 58psi cap is met though, fuel flow drops a bit due to excess being returned to the tank.

Typically a BAP is wired to fool the FPCM into thinking its still doing something, although all current is being fed straight from the BAP. When the BAP is off, current passes from the FPCM, through the BAP, to the pump so everything functions as it should.

[RWTD]

You need the proper data for the injectors you're using. My guess is they are the Siemens 60 "shorty". Greg Banish (eficalibrator) sells a GM training DVD via Summit Racing that has all the data for the various injectors Ford Racing offers, including both the shorty and tall Siemens 60. Also, keep in mind, your factory system is regulated to 58psi max, regardless of what you raise the pressure to in the tune, so leave it at 58. There is a mechanical blow-off valve on the pump assembly.

Whipple has all the proper data for those injectors, so I'm not quite sure why their GM tuner doesn't elect to use such?

[mowton]

We just received a 2006 SSR with a Maggie that the customer says had tuned, and here is the IFR table we found.......

[DSteck]

We just received a 2006 SSR with a Maggie that the customer says had tuned, and here is the IFR table we found.......

Lol. Physics got drunk on that day.

[ScarabEpic22]

Wow. Just wow. If thats the IFR...not sure the rest of the tune is close.

Stock Magnacharger tune?