Timing source table questions

[GrannySShifting]

Is there a difference how they are derived on say a 2016 GT vs a 2013? The system works the same except it doesnt use some mapped points if I remember right in the stock config like OP table isnt enabled on some, been few years since Ive looked at any Coyote stuff. What is the actual flowchart to arrive at final timing (Borderline-plus/minus knock-IAT or ECT modifiers-capped by MBT/Pre-Ign/Cyl Press/etc)

I thought it started with timing in Borderline table then would creep up if knock sensors arent pulling and can then add some up to MBT equivalent table value - so MBT is ceiling (as well as PreIgnition and Cylinder Pressure limit tables) Can you disable the knock sensors adding timing and still allow them to pull when they see knock (if I remember right no you cant you have to use a table as a ceiling like setting Borderline and MBT the same at WOT)

At WOT was supposed to be at Optimum Power MP only i thought but this looks like its using blend of 21-25, isnt there a way to force it to go to OP MP only at WOT?

How are the adders factored for MBT Lambda, Pre-Ignition Lambda, Cylinder Press Lambda? Is it when its COMMANDING that lambda or ACTUAL that lambda, and if its -1.3 is it subtracting 1.3 from the base value in the table?

[engineermike]

I wouldn’t think of mbt as a cap. Rather, it calculates the timing for torque modulation, borderline, mbt, pre-ignition, and cylinder pressure. Then it does a compare and low-select. Knock advance is only active when borderline is the one that’s low-selected, then it proceeds with advance. It will advance until it hits the advance max or the next lowest source. Unless it’s a gt500….that doesn’t act like all the other fords.

[GrannySShifting]

I wouldn?t think of mbt as a cap. Rather, it calculates the timing for torque modulation, borderline, mbt, pre-ignition, and cylinder pressure. Then it does a compare and low-select. Knock advance is only active when borderline is the one that?s low-selected, then it proceeds with advance. It will advance until it hits the advance max or the next lowest source. Unless it?s a gt500?.that doesn?t act like all the other fords.

OK then, explain your compare and low-select?

If MBT table isnt advance max, what is (if its not pre-ign or cyl pressure obviously)

Say your at 5000 rpm and air load of 1.0, what table does it choose to start at/why borderline or MBT and where from there

Can you make it 100% weighted to Optimum Power at WOT and how? I enabled (set from 0 to 1) Mapped Point OP in MP Config and it isnt using MP OP at all still. Snap to Point is disabled for that still, not sure what the snap to point does exactly. Some talk about paring down the MPs enabled, this has all but 13, 26 and OP enabled stock

[mstang_man]

Dont know if this will confuse you, but here is the tech definition. Hopefully i didnt miss anything..

starting around 2002, the MAXIMUM_ALLOWED_SPARK_TABLE disappears and is no longer used. This is substituted with a modified calculate of the MBT_SPARK_TABLE. The MBT_SPARK_TABLE is modified by two other spark tables to get a new MAX ALLOWED value. These two tables are used for modifying spark to reduce emissions, SPK_ADJ_FOR_EMISSIONS and another table to modify the MBT table for combustion noise, SPARK_ADJ_FOR_COMBUSTION_NOISE. These are both based on engine RPM and calculated engine load. These two tables modify the MBT_SPARK_TABLE and this becomes the MAX ALLOWED value on the newer applications. This value is then used in the above comparison when selecting the lowest spark. The max allowed and borderline tables have RPM on the X axis and Load on the Y-axis. Load is nothing more than engine volumetric efficiency. The production naturally aspirated engines will have a max load in the spark tables of around 0.9 or 90%. On a forced induction application volumetric efficiency will become greater than 1.0. To adjust for this, the load axis on the spark tables should be changed to allow values to go up to around 1.5 or 1.6. This way when the engine starts to build boost and volumetric efficiency goes above 100%, the spark tables, if calibrated correctly, will automatically remove spark as load goes up and this will prevent the vehicle form having to be recalibrated if boost is changed.

To get peak power out of a N/A car, the best thing to do is just take the MAXIMUM_ALLOWED_SPARK_TABLE and cut and paste it into the BORDERLINE_KNOCK_TABLE. This will give you the spark to make the most power based on dyno work that was performed by the OEM. The only other thing to change with this method is to make sure it will still allow spark to be retarded with hotter air temp and coolant temp. If you look at the calculation above to determine final spark, before it's compared to the other calculated spark values, you'll notice that if you put the MAXIMUM_ALLOWED_SPARK_TABLE into the BORDERLINE_KNOCK_TABLE and then add spark in for A/F ratio, ACT or ECT, the output of that equation will always be greater than MAXIMUM_ALLOWED_SPARK_TABLE. So, to still allow spark to be retarded for some conditions, eliminate all the positive values from SPARK_ADDER_FOR_A/F_WHEN_OPEN_LOOP, SPARK_RETARD_FOR_ECT, and SPARK_RETARD_FOR_ACT. This now allows the engine to run off of the best spark for most power, but still allow spark retard for coolant temp and air temp. Now when applying this logic to a 2002 GT that does not have a MAXIMUM_ALLOWED_SPARK_TABLE then you just simply take the MBT_SPARK_TABLE and paste this into the BORDERLINE_KNOCK_TABLE. In addition you will want to make sure you set SPK_ADJ_FOR_EMISSIONS and SPARK_ADJ_FOR_COMBUSTION_NOISE to all zeros. You cannot do this on a supercharged engine. You cannot put MBT spark everywhere and expect the air temp sensor to be able to compensate for it. In these cases you will need to lower the BORDERLINE_KNOCK_TABLE to compensate for the spark requirements.

[engineermike]

It’s like this….at any given set of conditions….

Calculate MBT as a function of load, speed, cam timing, lambda. Mbt = 30

Calculate borderline as a function of load, speed, cam timing, lambda, ect, iat, tip in, et al. Borderline = 24

Calculate pre-ignition as a function of load, speed, lambda. Pre-ignition = 26

Calculate cylinder pressure as a function of load, speed, lambda. Cylinder pressure = 32

Calculate torque reduction timing at a TR of 1.0. mbt - 0 = 30

Timing command = min(30, 24, 26, 32, 30) = 24. This is the low-select. Spark source = borderline

Then it starts adding at the specified advance rate. When it reaches the next lowest number, in this case 26, it stops advancing further but the spark source still reports to be borderline.

[GrannySShifting]

OK, so it starts at the lowest of those 4 table final results. usually should be your borderline spark table, then it will creep timing up until it hits the next lowest table value be it MBT or others.

If you set borderline and MBT the same then you will get THAT timing as long as Pre Ignition and Cyl pressure are set higher, with no knock it wont add but will subtract with knock like I was saying in original post right?

[engineermike]

If you set borderline and MBT the same then you will get THAT timing as long as Pre Ignition and Cyl pressure are set higher, with no knock it wont add but will subtract with knock like I was saying in original post right?

This is correct. I usually log borderline, mbt, and timing so I can see where it?s running relative to those numbers. Btw the gt500 works different.

[mstang_man]

OK, so it starts at the lowest of those 4 table final results. usually should be your borderline spark table, then it will creep timing up until it hits the next lowest table value be it MBT or others.

If you set borderline and MBT the same then you will get THAT timing as long as Pre Ignition and Cyl pressure are set higher, with no knock it wont add but will subtract with knock like I was saying in original post right?

generally on the older mustang 99-04 setting the base tune you would copy MBT and Paste into BNK, after getting the AFR correct dial spark from there. you may get 16-18*for SC and 18-21* on an NA car. The PCM will use the Borderline table or maximum MBT which ever is lower, for final spark. in theory you could get the best spark allowed..

[engineermike]

Man there is no way I would do that on anything modern. The compression is so high that mbt can be way above knock. You could throw it into severe knock before the knock sensors have a chance to help.

[Grim5.0]

How does a gt500 behave?
Learned a few things from the snap to line on those. Similar to the gen3 roush.

[engineermike]

Yes the gt500 and Roush mapped point locations and snap lines are eerily similar.

The way the gt500 controls timing is still somewhat of a mystery to me. Several fishy things going on.

1. Shift modulation torque management timing retard hangs around a full second after the shift finishes. A second doesn’t sound like much but that’s halfway to the next shift before it unleashes borderline timing.

2. Knock advance above 0 (added) is delayed further still, up to 2 seconds after it enters borderline source.

3. Knock advance hovers between 0 and 1 even though 6 is allowed.

4. Knock recovery after a knock event begins immediately after the event even though advance above zero is delayed.

Final timing on good pump gas only runs about 16 deg even when no knock is present.

I suspect the tuners are getting around this by simply commanding more borderline (and raising the cylinder pressure limit). It’s probably not a bad strategy but without understanding the logic behind the knock advance above zero it could be risky if some day the right conditions are met and all 6 deg of advance comes in.

I don’t know if or how they are dealing with the extended shift modulation spark cut. I suppose you could mess with the torque ratio s curves or fake out the mbt numbers to fool it into giving it more timing after the shift.

[murfie]

I don't think how the timing is determined is any different in the GT500's from any other modern ford ECU. Which ever spark source comes out the lowest. My guess is Fords strategy was just balancing it between how the IAT is doing and if the knock sensors say advance is allowed from fuel octane. Seems reasonbable to me, but they still had to nerf compression. BDL not falling below MBT until near 1.3 load. I dont think they get much over that at the stock 12PSI. It is basically going to run close to its MBT timing, unless very heat soaked or octane/ fuel quality is very bad. Even below 3K RPM its not until boost that BDL falls below MBT. There is not a lot to gain from more timing in stock form. If you want more power out of a GT500: increase the RPM limit, Pulleys, heat exchanger system upgrades to keep IAT in control and then fuel system to run enough E85 once you start to get that bordelrine lower.

I would say a 2020 GT500 should be more like 26-27* at WOT. 16* I would say its knocking or something is limiting torque through spark control.

so you can see how much interpolating this compare takes.

GT500 bdl vs MBT expanded.jpg

Then after

GT500 bdl vs MBT.jpg

[engineermike]

Murfie I spent a lot of time looking at the tune files before analyzing logs and tuning one. I know the tune looks like it works like all the other fords but trust me when I say it doesn’t. Either something is vey different in the algorithm or there are new tables that aren’t defined. It’s not knocking at 16 deg and even if it were it wouldn’t explain the behavior I’ve observed in 3 different cars at 2 different pulley sizes.