quick easy question from beginner Pentastar

[Benjamin Lopez]

hi all, sorry for my poor English, after some study here and there I still don?t understand where my Pentastar Chally 2011 engine CVM editor manages the amount of fuel (not visible solenoid time or any other means of fuel pulse or amount). I will try to explain deeper my doubt:
I can see in my VCM editor where:
AIR: volumetric efficiency table, in % of air filling the cylinders per each rpm regime
SPARK TIMING: I see table of spark advance corresponding to each aircharge (in grams) at each rpm regime also, both in base and in WOT
CAM TIMING: I see the inlet and exhaust advances also, measured in degrees and correlated to the cylinder aircharge in miligrams, both for base and WOT
BUT FOR FUEL: I only see stochiometric fixed value Fuel to Air ratio 0.0688 and then power enrichment.... my VCM editor does not show any injector opening timing and width where I can adjust fueling.

So again my question: where is it to play with the amount of fuel and the timing of the injectors for Pentastar? is it that it calculates constantly the stoich fuel for the air-charge I enter in the VE table, and it just adds a fixed % delta when I go WOT with enrichment? (difficult to believe, I think I misunderstand something around)
I am an old school mechanical guy, for me the tuning simplistic sequence is 1. Define air flows, 2. define fuel for that air, 3. define spark timing for that mixture/cam profile, here I am lost in step 2.

Thanks in advance, and thanks for your patience with me.

[Benjamin Lopez]

After no responses so far I will replay to my question with the latest I learned, hope helps another beginner also appreciated if somebody corrects in case I am misunderstanding:

- Fuel is calculated by ECM in base of Stoich constant proportion provided (VCM Editor-fuel), meaning computer will read (Calculate from MAP, etc) how much air comes into the engine and dose fuel in that proportion (ration) always constant regardless regime and load.
- If WOT conditions are met (pushing pedal does not mean immediate WOT condition met), then the stoich constant will be modified by adding the fuel enrichment table values (which original is a constant delta ration value across all conditions)
- The fuel amount is then operationally corrected by the ECM using O2 sensors feed back, (LT and ST trims)

I also understood how this ECM operates totally different to what I thought, it reads pedal command as "driver want torque", and processes that demand across torque management algorithm to end up commanding throttle angle accordingly depending on multiple circumstances (ECM decides how and if to provide the requested torque, for this reason % throttle tends to match pedal % along the time, but never have a same value like a wire would)

[Iceyrider]

The best way I can simplify it is this. Pedal voltage reads driver torque demand, ECU uses throttle body airflow model and VE tables to estimate how much to open throttle body for the desired airflow to produce the demanded torque (within limits), ECU uses injector mass vs pulse width tables to add enough fuel mass (usually in grams per second, per cylinder), and O2 sensors report lean/rich allowing ECU to target 1.0 Lamba in closed loop. In open loop, O2 sensors are ignored and the desired fuel mass is calculated based on estimated air mass. For example, A stoichiometric fuel air ratio for gasoline is about .0680 ( 1/ 14.7= .0680). If the desired power enrichment value is targeting 12.5 to 1, then 1/12.5= .0800 fuel air ratio. So, .0800-.0680= .0120 power enrichment. Assuming your injector data is correct, .0680 Stoich + .0120 added for power enrichment should give the result of 12.5 to 1 AFR. But, this only works if the VE tables are correct, and they are usually incorrect once a vehicle is modified for more airflow. That is why it is highly recommended to use a wide band O2 sensor for WOT tuning.

[Benjamin Lopez]

Iceyrider, its one of the more clear explanation I did read across all the chats reading and videos watching I have taken. Reading your short paragraph would have saved me tones of time of investigation a month and a half ago If I write you some private questinos would you replay? I still have some "whys" holes of understanding.

Example it took me one week to understand why my 3.6 penta has a feed forward TPS VS flow (large/small range) which shows 4 times more flow (8,400lb/h) than my engine pumping capacity (I calculate 1900lb/h max). Between reading to two guys in forum the light switched on and I investigated, I got to next conclusion:

I understand now the table is "specific throttle manufacturer standard curve" measured in "sonic flow", sonic flow is the amount of air passing through the throttle body with air running at sound speed... I made some calcs and the numbers appoint having sense, assuming some decent losses.

This explains to me why Hemituna said reducing that flow per each throttle angle, is increasing throttle response at PT, obviously when you reduce sonic flow in that table, you are kidding the ECU that your throttle body is smaller and the ECU corrects for more angle demand to achieve the flow target coming from the torque model. The ECU will have a non visible algorythm to translate sonic flow into engine flow using the throttle deltaP taken from MAP sensor.

Do you understand it same way?

[Benjamin Lopez]

Hey Iceyrider or anybody who may be interested, I attach here comparison file Stock VS "try1" comparing trends and explaining actions. If you or anybody has some time to watch and comment it will be valuable. I am trying to analyze why I did not get all what I expected with my change, all inputs valuable and welcome.