Power FC Injector question
 

if you have lets say the stock 850s in the car and go to the setting in the pfc and change the secondary to 1200 or 1300cc does it make a difference in the fuel settings or does it just change what the inj-duty would be if you had that kind of injector.

anyone?

bump

man thats why i posted this on the third gen section, no one goes to this section

You should try reading the manual.

An injector that flows 850cc of fuel is always going to flow 850cc of fuel. Think of it as a straw 0.850" in diameter. The diameter of the straw and therefore amount of stuff going through isn't ever going to change.

Questions like this are frightening. Hopefully you aren't fucking around in the PFC map setup so you don't wind up blowing your motor.

I have only tested, researched, and logged what the bottom two transistion values do.

Some of the other values, Maybe "Q" affects the PFCs calculation of duty cycle and is used for transistion form primary to both injector set. I have not tested the actual affects of the other values because the manual tells us to do the changes by their rules.

The manual does not tell how to change the two transistion values so I concentrated on them.

When I have time, maybe I'll get around to the rest.

not touching any thing in the settings, i asked this because i went to pettit and got their cool charge 3 and 1300s put in but and he had a tune from steve kan that cam uploaded but set it as 1200s.. the only thing im curious about is, if i were to go wot and lets say my max inj duty was 75, if i were to put 1300s in the sec-inj setting without touching anything else.just changing that setting would it show a lower inj duty, thats the only thing that i have been wondering.

any thank you for answering this, i know not many people come to the PFC section

I think I can probably answer this question. Both the Q value for primary and secondary does come into play.
The value enter in is what the PFC expects the injector flow to be so that it provides the proper fuel based on the injector size. The primary injector calculation has two parts. The % controls the amount of fuel (injector size) in vaccum, the Q value controls the amount of fuel in boost. To better clarify this, lets say you have 850cc injectors for primary. you enter in 64.7% instead of 100% for primary front/rear and left out 550cc for Q value, your car would drive normal in vacuum since the PFC adjusts its injector size to the value you enter in. However once you get into boost, the car will run extremely rich since the PFC still thinks you are only running 550cc injectors so it will provide the same amount of injector time as it would needed for 550cc injectors.
So to answer your question, yes it does lower your inj time and duty cycle when changing from 1200cc to 1300cc. it will also cause the car to run leaner.

just changing the value from 1200 to 1300cc when it was tuned for 1200 sec injector.
for a 550/1300cc combo, you can expect the a/f to approx 5% or 0.7 of a point leaner
for a 850/1300cc combo, you can expect the a/f to approx 4.5% or 0.6 of a point leaner.

it will flow 850cc for x milliseconds based on fuel map position. If injector size is doubled and map is same, duty cyle will be half ..providing same volume of fuel.

Steve, Thanks for the detailed explanation of "%". It answers my posted question too!

But Steve. Since he has a map for 1200's but actually has 1300's in place isn't he currently running 5% richer than what the map was based on (assuming a 550/1300 combo).

Hey Julian,
that's correct. The map he has *should* run richer giving he has identical setup from the map Cam loaded to his car. However by changing the value from 1200 to 1300cc will cause his car run 5% leaner than what he is currently running.
I have tune several cars running identical setup but just changing the engine port varying the fuel requirement from 3-12% more. I have a customer car that I just finished breaking-in the engine from a small street port to my stage 3 port, I added 10% of fuel on the map for an initial pull and still ran lean on an indentical setup. Although it will run a little too rich during inj overlap, I think it is still safer to run .5-.7 of a point richer until the car is tune without knowing the difference between his setup and the map he has.

ok thanks for clearing that up, also cam did change some of the maps a little, i believe it was running in 11afr on wot. hope to see you soon steve, really would like to get a good tune from you.

im thinking i should invest in a wide band to make sure i know what my afr's are

i want to log my afr's now, i was going wot last night and i was getting on the highway as i let off i cant remember if i shifted from 3rd to 4th or 4th to 5th (to cruise after the last shift), but i heard a loud bang i did have a battery jump box on the passenger floor with my work shoes next to it.

im not sure if maybe it pressed the chair lever from getting knocked back and as i let off it slammed and made that bang or it was the exhaust backfireing,
iv never hear a loud bang like that from my car before. My Gf's cousin was driving behind me and he said there wasnt any flames or anything.
Car drove fine home, pulled it in opened the hood so it dont heat soak and put the fan in front of the car to get the heat out the garage, started it 10 mins later and it was still normal, just gave me a scare, hope no damage was done.

what wideband should i get now. looking for something in the 200 range.

Steve,

I will need to get over to FW when I get my other mods and have you tune.