ty_ty13

iTrader: (42)

is there a table i can use in EFI live that will act like an accelerator pump does on a carbuerator?

thanks,

tyler

foff667

iTrader: (2)

here's some good info on this topic http://www.hptuners.com/forum/showthread.php?t=10872

SSpdDmon

iTrader: (10)

Good info - yes
Useful - no

He's asking about EFI Live, not HPT.

ty_ty13

iTrader: (42)

bump...

Lextech

iTrader: (18)

Go to EFILive .com > Forum >General > Power Enrichment Quetions.

405HP_Z06

iTrader: (11)

In short, the answer seems to be no. In the link above from the HPT Forum, Chris describes the pumpshot function as:

"In the LS1 the pumpshot actually comes from the airflow side (TPS and MAP based predictive filtering) ie. the dynamic airmass calculation models it as an "airmass shot". This is only used when the dynamic airflow calc is running (ie. the MAF is working) and its complex as hell."

If you looking for transient fuel, than this should help:

"There are 2 main parts to this.

1. The Fuel Evaporation part
This is a model of how fast the fuel evaporates off the intake surfaces. Smaller numbers mean the fuel evaporates faster. What this means is that more of the fuel you inject from the injector that hits the intake surfaces makes it into the cylinder faster and the effects of any transients are shorter. This is pressure and temperature dependant process that follows an exponential decay law. Fuel boils off faster under vaccuum and at higher temperatures. There is also an airflow based gain that modifies the evaoration rate based on airflow.

2. The Extra fuel hitting the walls on each injector pulse
On each injector pulse a certain amount of fuel hits the intake surfaces and adds to the amount of fuel already there that is boiling off. Higher numbers mean more fuel hits the walls (hence less directly in the cylinder), meaning the PCM has to inject more fuel than it thinks. You'll notice that the numbers get smaller as the intake gets hotter and also bigger as manifold vacuum drops as you would expect. There is also a gain component that multiplies this value with airflow, as higher airflows mean less fuel will impact the walls etc.

You can think of this whole impact/evaporation process as a "leaky bucket", you have a bucket (the intake surfaces) that has an amount of water in it (an amount of fuel on the surfaces) that is leaking out (evaporating off the surfaces). You also have a hose that is filling the bucket at a certain rate (the fuel injected that hits the intake surfaces).

When you put it all together you have this:

1. Injector fires with the intent to inject a certain amount of fuel into the cylinder (Fdesired)
2. some of the fuel goes right into the cylinder (Fdirect)
3. some of the fuel hits the intake surfaces (Fimpact) and adds to the amount of fuel already there from previous cycles (Fwall)
4. some of the fuel that was already on the intake surfaces evaporated during the last cycle so it went into the cylinder on this cycle (Fevap), along with the fuel that already went directly in.

So the total amount of fuel that went into the cylinder (Fcyl) was:

Fcyl = Fdirect + Fevap

and

Fevap = Fwall(e-boiling time) ... an exponential decay

Fimpact = Fdesired * impact factor * gain

Fwall(new) = Fwall(old) + Fimpact - Fevap

From this you can hopefully see (if your head hasn't exploded yet) that there are 3 possible states this can be in:

steady state condition
Fevap = Fimpact then the actual fuel amount (Fcyl) equals the desired injected amount (Fdesired) so the PCM doesn't inject any extra fuel to compensate (no need to increase Fdesired)

positive MAP transient, you hit the gas
Fevap < Fimpact then Fcyl is less than Fdesired, because more fuel is adding to the fuel on the intake surfaces instead of going into the cylinder, so Fdesired must be increased by the difference between Fimpact and Fevap for a short period. This means the PCM needs to inject more fuel than it initially thinks otherwise a lean spike will occur.

negative MAP transient, you take your foot off the gas
Fevap > Fimpact then Fcyl is greater than Fdesired, because fuel is still evaporating from the intake surfaces instead and going into the cylinder, so Fdesired must be decreased by the difference between Fimpact and Fevap for a short period. This means the PCM needs to inject less fuel than it initially thinks otherwise a rich dip will occur.


The main things to mess with are the Impact factor and its gain and the boiling time constant and its gain. eg. you can see that in the stock tables as MAP increases (you hit the gas) the boiling time increases (fuel evaporates slower) and also the impact factor increases (more fuel hits the intake surfaces), both of these increases result in the PCM adding more fuel during the transient. You can also see that as MAP decreases the numbers get smaller, resulting in the PCM subtracting fuel for the transient.

Hope that helps,

Chris..."

Lextech,
Nice to meet you at the EFILive-101 course!

foff667

iTrader: (2)

Um...same pcm's though no?

SSpdDmon

iTrader: (10)

The PCM's may be the same. But, IIRC, there are some features/tables that HPT provides that EFI Live doesn't just as there are some features/tables that EFI provides that HPT doesn't. I think this is one of them...

ty_ty13

iTrader: (42)

405,

im not sure what im looking for i just know that even though i have my lower ve and timing nailed i still get a hesitation with a quick WOT and release... and i know if its doing it with that then its also hesitating when i footbrake the car from 35%tps to WOT on the last yellow bulb at the track....