Figuring out injector dead times in ms2?

[lagos]

I'm using a DIYPNP with sequential injection on a 3sgte engine, with low impedance 440cc injectors that use a resistor pack. I'm trying to figure out the correct injector dead time @ 13.2v.
Currently the dead time is set at 1.0ms. If I change from 2 to 4 squirts at this dead time, the car simply stalls out from going too lean. If I up the injector dead time to something like 1.2ms, my car will idle at 4 squirt, however going back to 2 squirts will make it extremely rich. If I continued to add even more dead time, my 4 squirt setting will get richer, but my 2 squirt setting will continued to read off the charts rich. I've taken it up to 1.9ms dead time and at this setting 4 squirts seems to be almost as rich as 2 squirts, however this seems absurdly high, and my fuel pw table needs to be set to single digits to try and get the car to a stoich idle.

Is there something I'm missing while running this test? The injectors are set to sequential/semisequential and injector drivers are set to additional drivers.
I was under the assumption that doing this test should be done in batch fire mode only, and that i could potentially put the car into batch mode by turning off additional drivers, however when i tried this, the car stalled out and felt like it was only trying to run on two cylinders.

[nismoautoxr]

you do know that you have to do a ignition cycle after each of those changes in squirts right?? You cannot do it on the fly while the engine is running. From my experience...there is no way 1.9ms dead time would be appropriate. For a lowz injector you will likely be looking somewhere in the .5-.9ms range..

[lagos]

you do know that you have to do a ignition cycle after each of those changes in squirts right?? You cannot do it on the fly while the engine is running. From my experience...there is no way 1.9ms dead time would be appropriate. For a lowz injector you will likely be looking somewhere in the .5-.9ms range..

No, I did not know that. The car seemed to switch over from 2-4 squirts and tuner studio never prompted that an ignition cycle was needed. I will try this again with a power cycle.
As for the .5-9 range, it was my understanding that when using low impedance injectors with a resistor pack, the dead times would be treated like high impedance and be in the 1.0+ range.

[racingmini_mtl]

The number of squirts is not used when the sequential/semi-sequential mode is selected. So changing it won't change anything other than computing the wrong req fuel.

If you want to find the dead time by changing the number of squirts, you will need to run in untimed mode.

Jean

[lagos]

The number of squirts is not used when the sequential/semi-sequential mode is selected. So changing it won't change anything other than computing the wrong req fuel.

If you want to find the dead time by changing the number of squirts, you will need to run in untimed mode.

Jean

That would explain a lot!
So untimed mode is basically batch fire mode?
I'm assuming that I would also keep Additional Drivers enabled?

Does 2-4 squirts really need a power cycle?

[nismoautoxr]

Now I have been away from MS2 extra code for quite some time but as far as I know ....a change of squirts or injector staging still requires a power cycle . I could be wrong . Im sure if I am ....someone will correct me.

Yes batch fire is untimed injection.

Not sure about additional injector drivers but I would say you should not disable them or you will lose 2 injectors but I dont know how those are handled due to the fact those are added on to the diypnp so i dont know if they are allowed for in the code when using untimed injection ...thats absolutely for Gene to answer I think.....or whomever the extra injector board is through.

I missed/glossed over the detail that the op was using sequential/semi sequential injection....my mistake.

FWIW I have a set of bosch highz injectors in my LS1 which came in it stock and I measured .550ms deadtime so there is not necessarily a cookie cutter rule of thumb when it comes to high and low impedance injectors . There is "typical" then there is "actual"

BTW ...

[racingmini_mtl]

Yes keep the additional drivers enabled and yes the power cycle is needed. In batch mode (untimed injection), injector channels 1 and 3 are fired together and channels 2 and 4 are fired together (and if you're using simultaneous then they all fire together).

Jean

[lagos]

Thanks so much for the help. I was able to successfully figure out my dead time at 0.89ms using this method. Hopefully this resolves the majority of inconsistent a/f ratio readings that I've been dealing with.

[jsmcortina]

I updated the ini file for the next release so it says "Power Cycle Required" if that setting is changed.

James

[lagos]

I updated the ini file for the next release so it says "Power Cycle Required" if that setting is changed.

James

Great!
It would also be helpful to know that going from 2-4 squirts with sequential injection, basically does nothing useful.