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Pfc Injector Map Tuning

gawdzilla

By gawdzilla,
in Engines & Forced Induction

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gawdzilla Contributor

gawdzilla

Posted
Posted (edited)

Just wondering if you guys try to keep 1.000 as ~14.7 A/F like the manual says.

Reason I ask is because I find that the Injector map number does not always correspond to the correct A/F.

I am running 555 nismo injectors, and did the 78.5% overall injector compensation. I found this leaned me out up top, so I bumped up the Injector map numbers. Some are now maxed out at full enrichment (1.496 which should correspond to a ~9 A/F ratio, but it definitely is about 12 A/F), and I want more resolution up top so I can add even more fuel if necessary.

My question is, is it common for people to use bigger injectors and keep the OVERALL compensation at say 100%, then lower the entire Injector map so the numbers don't correspond to A/Fs anymore? I am thinking about doing this so I have more resolution in the top.

Please no "go to a dyno and get it done" posts, I want to know how its supposed to be done. If i went to a local dyno I would probably still be the one making the changes. I've got wideband, egt, and fc datalogit right now, so any suggestions would be appreciated, thanks.

Edited by gawdzilla
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T04GTR Grand Master

T04GTR

Posted
Posted (edited)

1.00 lamba is 14.7:1 afr.

1.4 is lean as f**k.

<1 is rich >1 is lean

you need to acuratly check the flow and work out the corect compensation.

i had the same problem putting 550s in place of 440s in a gtr with an autronic.

it can be adjusted mathematicly but the "responce of the injectors will be off so it will be too rich onto boost and to lean up top for example.

basicly adjust it to get the exact same afr as before the swap

Edited by T04GTR
Cubes Grand Master

Cubes

Posted
Posted

gawdzilla,

You are right... greater than one is richer, less than one is leaner.

Unfortunately your going to need a wideband if you don't want to throw it on a dyno.

Zero out the inj correction percentages and tune the map to achieve the afr's your after. A mate of mine runs 550cc's, from memory his inj map to achieve stoich is around the 60 somethigns. 66 seems to ring a bell.

If having the inj map looking a little messy bothers you grab a datalogit and use the recalc base function after its tuned. This will set the entire map to 1.000 hence 14.7:1.

The only real problem with doing this is it also sets the moderate and high load inj. values to 1.000. Obviously these map area's are not 14.7:1.

I haven't used the recalc base function myself but do plan on doing so. From what I gather the only way to achieve a 'normal' looking afr map is to do a few little tests with pfc fuel values and the 'real' afr. Perform the adjustment calcs required on certian load points hit recalc then perform the calcs again.

Hope that makes sense.. I've had to cut it short as I am heading out. :P

gawdzilla Contributor

gawdzilla

Posted
  • Author
Posted
1.00 lamba is 14.7:1 afr.

1.4 is lean as f**k.

<1 is rich >1 is lean

T04GTR, you are talking about wideband lamdas, while i am referring to the PFC injector compensation number.

gawdzilla,

You are right... greater than one is richer, less than one is leaner.

Unfortunately your going to need a wideband if you don't want to throw it on a dyno.

Zero out the inj correction percentages and tune the map to achieve the afr's your after. A mate of mine runs 550cc's, from memory his inj map to achieve stoich is around the 60 somethigns. 66 seems to ring a bell.

If having the inj map looking a little messy bothers you grab a datalogit and use the recalc base function after its tuned. This will set the entire map to 1.000 hence 14.7:1.

The only real problem with doing this is it also sets the moderate and high load inj. values to 1.000. Obviously these map area's are not 14.7:1.

I haven't used the recalc base function myself but do plan on doing so. From what I gather the only way to achieve a 'normal' looking afr map is to do a few little tests with pfc fuel values and the 'real' afr. Perform the adjustment calcs required on certian load points hit recalc then perform the calcs again.

Hope that makes sense.. I've had to cut it short as I am heading out. :(

thanks for the input. thats exactly what I was asking about. your explanation makes sense to me. btw I do have a wideband that I am inputting into datalogit.

I actually just tried out my "new map" with the total compensation set at 0, and my injector map leaned down a lot to compensate for the injectors. .809 ends up being pretty close to 14.7:1 for me. i'll look into the recalc base function and see how that works out. What values are modified by the recalc base? overall injector compensation %age?

Cubes Grand Master

Cubes

Posted
Posted

The recalc base from what I understands basically places a correction value on the base map so the values as all 1.000 on the map that is editable.

As I said in the prior post, it does cause problems with the moderate and wot areas of the map as it too sets them to 1.000.

It will require a little fiddling as I haven't fiddled with it.

You may be able to simply set the moderate and wot load areas to 1, do the recalc base then set it back to what ever, in theory if the origional value is 1 it 'shouldn't touch it when it does the recalc.

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