Dodge Injector Calibration Values

[ElecTech]

Can anyone (Chris, Greg, other Dodge tuners) try and explain how Dodge characterizes injectors in thier operating systems? I've seen some of thier injector tables, but I am having a little trouble getting my head around them.

It would be nice if someone could try and relate them to the Ford or GM tables I'm more familiar with and maybe give a proper method for "adjusting" them for larger, known injectors (FMC, Mototron, etc).

[Chris@HPTuners]

they use two main tables, they are the inverse of each other.

One is Injector PW (msec) vs. Fuel Mass (grams). This tells the PCM how long the pulse width should be for a given mass of fuel to be injected. The other is the fuel mass delivered for a given injector pulse width (why they have two tables, no idea). The they have multipliers that tell the PCM how this varies with manifold vacuum and other things.

Then they have a regular injector offset table, that varies with ignition voltage.

[ElecTech]

they use two main tables, they are the inverse of each other.

One is Injector PW (msec) vs. Fuel Mass (grams). This tells the PCM how long the pulse width should be for a given mass of fuel to be injected. The other is the fuel mass delivered for a given injector pulse width (why they have two tables, no idea). The they have multipliers that tell the PCM how this varies with manifold vacuum and other things.

Then they have a regular injector offset table, that varies with ignition voltage.

So is it safe to say that the flow values are actual values based on the injector flow rating?

By this I mean:

Injector flow = 7.31 g/sec

so

1ms PW = 0.00731g of fuel

no short pulse data or anything else factored in to populate this table?

[redhardsupra]

if you had a fuelmass vs IPW curve, that would be the resulting curve that involves all the nonlinear characteristics of fuel delivery. that's actually nicer than either GM or Ford.

[Chris@HPTuners]

So is it safe to say that the flow values are actual values based on the injector flow rating?

By this I mean:

Injector flow = 7.31 g/sec

so

1ms PW = 0.00731g of fuel

no short pulse data or anything else factored in to populate this table?

yes and there is an inverse table as well, where 0.00731g = 1ms. It could have been done this way due to division being a very intensive calculation for earlier cpu's to gain throughput and it has stayed ever since. dunno.

in theory these 2 tables contain all the injector non-linear & linear characteristics. The vacuum based multiplier then contains the pressure drop charactersitic. There are also fuel flow and temperature based multiplers as well.

[BlackZJ]

Does this relate to all Dodge PCMs or only NGC?

[Chris@HPTuners]

Does this relate to all Dodge PCMs or only NGC?

jtec is different

[BlackZJ]

jtec is different

Is it more like GM or completely different?

[Chris@HPTuners]

Is it more like GM or completely different?

from memory its a 3d table of injector PW vs RPM vs MAP or something like that

[BlackZJ]

from memory its a 3d table of injector PW vs RPM vs MAP or something like that

OK, thank you!

[hexdummy]

There is a global injector offset value, some calibrations I've seen use it, some just use the main fuel pulse width look up table as Chris mentioned. Also, there is a injector pulse width vs battery voltage offset table.