VCT Map Point & DI Injector Question

[wristshot]

Just trying to figure some things out. Getting my feet wet on a 2015 2.7L F150.

First my "OP" Mapped Point is not enabled, yet when I log Mapped Points the OP shows heavy weighting as depicted in the following images.

001.jpg002.jpg003.jpg

In addition, the OP Mapped Point is being called under very light loads. During heavy loads Mapped Points 3, 4, & 5 are utilized (not shown).

Can anyone provide insight why this is. I would not expect any activity on the OP (Optimum Power) Mapped Point - especially during light loads.

Also, I don't understand what the "VCT Distance to OP" is? It is logged as 60 & 63 in the above log screen shots. Seems like it should be close to 0 with the OP at 50 plus (94) percent.

Secondly some questions about Injector Timing & Limits.

004.jpg

1. The Max Duty Cycle has a range of 0 - 2.000. I would think a value of "1" is 100% Duty Cycle (i.e. could be on for the entire injection event as defined in Timing)? Would this be true and values greater than "1" would have no effect?

2. "SOI Minimum" scaler (383 degrees in my tune) - The way this is worded, it seems that the injection event must begin at, or after, 383 crank degrees not before.

3. The "Single Injection Intake" (Normal & Cold) tables have values less than 383 degrees (i.e. 285 in the table depicted). What am I missing here?

I appreciate any thoughts or clarification.

[SultanHassanMasTuning]

go to your SD section and you will see why. follow the mapped points on your log under the HDFX system

[wristshot]

I'm not sure what you are referring to in the SD section.

My stock tune does not have the "OP" Mapped Point enabled AND none of the Quadratic Air Charge SD tables are populated with data (see following image).

006M.jpg

[metroplex]

That is the same with the SHO, none of the tables for the OP point are populated with data.

[Bugasu]

1. The Max Duty Cycle has a range of 0 - 2.000. I would think a value of "1" is 100% Duty Cycle (i.e. could be on for the entire injection event as defined in Timing)? Would this be true and values greater than "1" would have no effect?

2. "SOI Minimum" scaler (383 degrees in my tune) - The way this is worded, it seems that the injection event must begin at, or after, 383 crank degrees not before.

3. The "Single Injection Intake" (Normal & Cold) tables have values less than 383 degrees (i.e. 285 in the table depicted). What am I missing here?

I appreciate any thoughts or clarification.

The max duty cycle settings creates a windowed limit based on a calculated maximum pulsewidth in crank angle degrees. SOI and EOI are defined in degrees BTDC, like spark advance. I'm trying to remember here, and when I get home tonight I can double check, but I believe SOI Minimum Clip is actually in ATDC, unlike the other SOI measures. Converting this to BTDC means that value is equivalent to 337* BTDC. It's the "minimum" because its the earliest you can inject. EOI Clip on the other hand in BTDC. The ECU calculates how much fuel you need, and determines when EOI Actual should be. At the high end, the latest it can inject is the EOI Clip. The earliest it can inject is SOI minimum. So you have a maximum injection window of SOI Minimum(BTDC) - EOI Clip(BTDC). This can be clipped further by the Max Injection Angle.

So, for a given condition, if you have a max injection angle of 255*, and you're injecting for a calculated 200*, you're at 0.784 DC. Now, how the DC limit works is it calculates the fuel flow that would be that limit * your max injection window. So, 0.95 * 255 = 242.25*. It then based on desired AFR and fuel flow amount at that injection duration, it calculates the airflow that could be supported. It sets an airflow limit at this airflow. If you ever hit it, your airflow limit source would be Insufficient Fuel Flow.

The goal of the system is to prevent fuel rail pressure drops and running out of fuel and running lean. Now, you could adjust it for example so that your Injection DC Limit was 1.1. This would mean this airflow limit would be calculated for a hypothetical amount of fuel at 280.5* of injection duration, which you shouldn't be able to hit because of your injection clips anyways, and thus could effectively remove your Insufficient Fuel Flow issues. A smarter option instead would be to tune the system and find the point where your injection duration starts to cause fuel pressure to drop, and then set your max injection window as such, and the DC limits allow you to dial in a "safety" airflow limit cap, preventing you from ever exceeding that airflow amount (and thus causing the ECU to limit airflow to that value by controlling the throttle and wastegate).

Hopefully this covers your injection questions.

[wristshot]

Thank you Bugsau. It all makes sense now. I was hung up expecting both the scaler and the tables being in crank degrees based on the power stroke beginning at 0 degrees TDC. It seems as though the SOI Minimum scaler is in cycle crank degrees and the Single Injection Intake (Normal & Cold) tables are relative BTDC (0 degrees).

Your explanation of the Duty Cycle is great and makes perfect sense. I knew the DC was related to the injection window, but was struggling with what the window was.

I'm was on the same page with you about opening up the window though, that's why I was trying to understand how these variables relate.