Played Around With Pfc And Splitfire Coil Dwell And Stuff...

[STATUS]

Also it cant be duty cycle based as all nissan's use dumb ignitors.

In a 300zx for example there is is a 32 byte table (location 7b50-7b70) . It represents Ignition Dwell Duty, the values in the table * 0.33, represent percentage of Dwell Duty. Scale: 400 rpm to 12800rpm in steps of 400 rpm.

Edited May 4, 2007 by URAS

[noone]

When installing my new splitfire coilpacks I remember reading that they recommend going to a heat range cooler plug as well

would this mod to PFC settings be done as well as cooler plugs or instead off cooler plugs, am still getting a bit off knock 60-80 range with the new tune and am thinking off trying both plugs and these settings to try an sort it.

I assume dwell changes allow for better coil saturation and resultant "better" spark yeah?

[Adriano]

Yep, and the colder heat range plugs should reduce the knock a bit.

Upon researching the stock settings for dwell , the recharge time of the coils is rpm dependent, and follows the torque curve, i guess nissan realised the coils would overheat if given a set dwell, so they increase it around 4000rpm, and it drops off steadily both sides of this.

[noone]

cheers for the reply bud it was knocking a bit, much the same, before the new coils will give plugs a go I think an (as I dont have datalogit) chat to my tuner bout changing these other settings

interesting how you say the dwell settings drop off after 4000 rpm coz it seems to be after 4000 to bout 5000ish mine seems to be struggling

Edited August 20, 2007 by noone

[Adriano]

interesting how you say the dwell settings drop off after 4000 rpm coz it seems to be after 4000 to bout 5000ish mine seems to be struggling

Thats for the stock ecu, setup for the stock turbo, i would find a dyno shop with datalogit, and just get them to change the dwell settings, if you want a bit more grunt there, no need to put it on the dyno to do it, shouldnt cost much.

[The Mafia]

I'm going to keep an eye on this.

Is there a chance that this could fry my Splitfires?

[noone]

Could b wrong Mafia but i dont think either setting could hurt em but stock type settings just wouldn't utilise the coils to the max as they dont have enough time to get full satutation so dont put out the maximum spark they can do.

If only I had a copy of datalogit I could find out without having to try an convince my tuner

[Mr Jollwah]

It seems that the amount of dwell drops off after 4000 rpm because the maximum value that nissan use is E9 (Hex), It is scaled against rpm as a dwell duty %. As rpm increases there is less time between firing events to charge coils.

There seems to be a few differing methods of determining dwell duty %, 1. Divide by 10 , 2. Multiply by .33

[hardsteppa]

On ‎4‎/‎05‎/‎2007 at 10:05 AM, STATUS said:

There is almost always two settings;

IGNITION VOLTAGE DWELL COMPENSATION (amount of time added to base ignition dwell as a function of ignition voltage)

IGNITION DWELL PERIOD ((length of time the ignition coil dwells as a function of rpm) sometimes this is a percentage of duty, like remaps for example)

I'm putting R35 coils onto the RB25 shortly, and seems adjusting the dwell in a Power FC isn't straightforward as there's no table labelled  " Dwell Ms > Voltage" , and all the info I can find on setting up the R35 coils refers to directly entering the specified ms against the voltage point.  While researching I read one post saying the "IGN Vs BattV" table referred to adjusting the actual IGN timing rather than dwell, but it would make much more sense if it referred to the dwell compensation as noted above by Trent, although doesn't seem he was specifically referring to the PFC. 

I also found this post screenshotted below, and the formula makes sense, giving around 1.7 as the dwell for stock coils.

so from there, with that formula making the figures in the "IGN dwell vs RPM" > "Adjust" column around 1.7 for stock coils, to get the R35 coil dwell into the mid-4ms range needed at 14 volts you would need to enter the new increased values into the "Adjust" column at each rpm point, and once done, then move to the "IGN vs BattV" table and enter the change at each voltage as a percentage to get the desired ms at each voltage point.  

 

Does that make sense, or does anyone have any details on how new coil dwell should be set up in the PFC? ..thank you

 

Edited July 28, 2019 by hardsteppa

[hardsteppa]

further to that, found that FC Pro labels it a little differently >>

 

So seems yes it is for dwell change rather than timing. 

[burn4005]

whats a power FC?

[KiwiRS4T]

11 minutes ago, burn4005 said:

whats a power FC?

You're too young to remember!