DSMLink and PTE 1000CC Injectors

[N1te]

I'm trying to figure out what global settings and dead time to use for the following fuel setup:

Walbro 255 LPH fel pump, PTE 1000cc injectors, Aeromotive FPR, Tech-Edge Wideband, DSMlink.

 

[jaday]

I'm no expert, but shouldn't you be asking these kinds of questions on the DSMLink forum?

 

[Boost92awd]

I'm no expert, but shouldn't you be asking these kinds of questions on the DSMLink forum?

You beat me to it. Dsmlink.com will give you the answers you are looking for.

 

[snowborder714]

Base Injector Data

 

[N1te]

The ecu was already installed by my builder, wouldn't it require unbolting the ecu to pull the code from the back of it?

 

[N1te]

Base Injector Data

They don't show the deadtime for PTE 1000cc's =\

 

[Splitpi]

In my opinion, Start with the FIC 950's values. PTE 1000 are rated at 90% Duty Cycle.. so its kind of misleading. Tweak from there.

Though run it on the DSMLink forum as well.

 

[DSMinn0vati0ns]

right form the dsmlink manual

Basic Global and Deadtime
Aftermarket injectors are sized "larger" than the factory injectors so as to provide more
fuel in the same amount of time. This scaling of fuel flow is easy to calculate and deal
with. Simply divide the old flow rate by the new rate and subtract 1 to estimate the
"global" adjustment you need in order to compensate for the new injectors. This does
assume both injectors are rated at the same pressure. As an example, consider the
purchase of 720 cc/min injectors.

Adjustment = 450 / 720 – 1.0 = 0.625 – 1.0 = -0.375 or –37.5%

So in order to scale the ECU's fuel curve down to compensate for 720 injectors, we
would need to reduce the ECU's fuel calculations by 37.5%. But there's a trade off with
larger injectors. You don't just get more fuel flow; you also get slower response.

The ECU takes into account the response characteristics of the factory injectors when
calculating how long to "fire" them. It first calculates an appropriate time from airflow,
knock, and all sorts of other data. It then adds an amount of time based on battery
voltage to account for how long it will take the injector to physically open up after being
told to do so. This injector response time is referred to as dead time, dwell time,
saturation time, and probably a whole slew of other names. It's a characteristic of
injector design and size.

The Dead time area of the Fuel Adjustment dialog is where you can make adjustments
to this dead time figure. The value entered into this area gets added to the value
calculated by the ECU. While there is a way to calculate what this value should be, a
trial and error approach tends to work best. Use the long-term fuel trim (SelectedLTFT)
value calculated by the ECU as your guide. The following outlines a good procedure for
getting the dead time right for your setup.

1. Car must be fully warmed up then must be operated at cruise for about 10 minutes
followed by idle for 5 minutes to get stable LTFT values.
2. Compare the LTFT at idle and cruise. You want both to be right about zero (+/-
5% or so).
3. If the two are about the same, dead time setting is good.
4. If they are equal but non-zero, adjust the global setting.
5. If idle LTFT is more positive than cruise LTFT, increase the dead time, less,
decrease.

The following table can be used as a rough guide when trying to dial in new injectors.
The dead time values are provided as examples of what we have found to work well in
the cars we have tested or have been submitted to us by our users. Your particular set of
injectors may need slightly different values, but these should be close.

Size (cc/min) Global (%) Dead time (ms)
RC 550 -18% 180
Hahn 625 -18% 180
Denso 660 -31% 180
Denso 720 -38% 450
PTE 580 -16% 180
PTE 680 -30% 210
PTE 780 -40% 315
PTE 880 -46% 330
FIC 650 -31% 315
FIC 750 -40% 315
FIC 850 -47% 315
FIC 950 -53% 315

A minor quirk in the implementation of the dead time value adjustment requires that any
value entered into this dialog must be evenly divisible by 15. The software will
automatically make appropriate adjustments for values you enter that are not evenly
divisible by 15.