12P Conversion

[Dylan]

Im in the process of doing some fine tuning to a mates car. Holden V8 355 in a VK.
Was previously tuned using VN code $DB. Car was running perfect and the inlet manifold has been changed now just needs a touch up.
So ive converted the $DB tune to $12P, ordered a wideband from 14point7.com (yet to arrive).

Started it up in the shed to check tune works and NVRAM working. All ok.
Gave it a rev in neutreal and its very rough on the throttle response a bit hesitent. This does not happen with the original DB bin.

I have a quick log of it to post along with both bin's. I havent changed anything since then untill i get the wideband on it.
Just thinking out loud it could be AE need adjusting or maybe spark? Hopefully I've just missed something.
Ive done the same thing to my own car and ran without problem on 12P with just the same tables changed.

I copied injector rate, idle and main spark, VE and run AFR tables across from DB to 12P.
The DB AE tables are different but not sure if they are coded the same?

Open to any feedback please.

[Holden202T]

there is a difference in the way AE works with $12P v's $DB .... i found this out a few weeks ago, can't remember if it was FB or DB though ....

so with $12P you can change the AE v's rpm where as with $DB you have a AE v's TPS multiplier which applies the same multiple across the board ....

if you've gone to a different manifold that will definately screw with AE ... especially if its single plane ....

i'd suggest try increasing the $12P AE at the right rpm for where your issue is and see if it fixes it .... but also keep in mind if the VE is out in that area it will be effecting AE too so make sure its right before going to hard on AE.

[Dylan]

Thanks mate I will look at that. With the DB bin the problem is not there even with the new intake pitty I cant log it.

[Jayme]

the injector bias tables are different to a stock $DB bin too. I would copy those across if you are trying to replicate the original tune. the AE is a bit different to a stock DB too, so as holden202 said, start upping that a bit.
in the past ive seen that early codes tune values dont seem to copy straight across to the later type codes such as 12P, it ends up a tad lean in the later codes.

[Dylan]

Thanks Jayme I will look them up. For an amateur like, how does that table effect the injectors?
Im not on my PC to look at it right now sorry.

[Jayme]

one table is the amount of pulse to add on to the commanded injector pulse at each battery voltage level. it helps keep the tune the same when the voltage to the injector varies. the other table is the pulse adder that adds the calibraiton value onto the injector pulse at each injector pulse ms in the table scale.

[Dylan]

I will compare those tables tonight. Whe I converted the bin for my car they were fine left as standard 12P settings both are running blue top injectors.
Mine is 304ci but this one is 355ci big dufference in cubes I guess but the injector rate is .12 from memory.

[Holden202T]

well if they are both the same injectors there needs to be a difference in injector rate !!

I believe blue tops are 24lb ? so a 304 should be about .11 injector rate and the 355 should be more like .13

if what I have said above is correct then that means the 355 will be lean, and changing the injector rate to .13 will richen it slighty across the board, this may well solve some of your stumbles without having the change anything else!

[Dylan]

Found 2 tables in each xdf.
In the $DB xdf theyre called "FUL RUN INJ BIAS BAT" and "FUL RUN LIN INJ BIAS BAT"
The $DB bin used the BDJH VP 200kw Clubsport bin as the base.

In $12P xdf i found "Injector - Injector Bias vs Battery Voltage" and "Injector - Injector bias add-on vs Injector pulse width"
Im thinking those 2 are an equivelant table? Also the figures correspond between the two bins.

But $12P has a table labelled "Voltage compensation vs Battery voltage" and i cant find an equivelant in the DB xdf.
I will do some trials next time im with the car but that wont be untill this Saturday hopefully the wideband will be here by then.

[Dylan]

well if they are both the same injectors there needs to be a difference in injector rate !!

I believe blue tops are 24lb ? so a 304 should be about .11 injector rate and the 355 should be more like .13

The new one i just done for the stroker is .1299 and my 304 is .1197

Bit of a muck around i guess converting tables from old tunes for you experienced guys, but considering it was just a manifold change i didnt want to start again, also ive never tuned an engine from scratch. Hardly even touched one up really.
Ive read plenty of info from here and kalmaker years ago but that half turned me off.
Im really hoping to learn a lot from this real world experience!