Any idea what the torque demand numbers mean?

[cobaltssoverbooster]

Are you sure about this? I'm still new to this, but engine vs. wheel tq will be gear dependent. If we ignore the trans/rear-end multiplication of TQ then really all we are talking about is the efficiency of these which doesn't seam important to me. In such a case I don't see how you would arrive at negative TQ. It seems more likely to me that these values are just engine.

If I'm right, then a more negative value will result in more engine braking. Negative TQ should just be the FMEP and PMEP of the engine (again, if my understanding is correct). The only parameter we can impact is PMEP by closing the throttle. The zero-fueling TQ will become more negative as engine speed increases due to FMEP. It would be interesting to know if anyone has figured out what this is because I would think you would basically want that to occur at a fixed pedal position. Typically I would think this would be calibrated to be near zero pedal, but it might be interesting to have it occur at part throttle at higher engine speeds so that engine braking could be modulated.

Daniel

yes it is gear dependent but the ecu is only tracking this as a 3d field not a 4d field. it also tracks it best in terms of 1:1 transmission ratios.

[marksawatsky]

What is your best guess on what would be the ideal torque table for good engine braking? Highest minus numbers across top row then tapering down (up?) towards the 20% throttle opening row?

[deepak]

From my observation, you can divide the whole map into four parts like cartesian plane with x and y reference axis. Take 70 on rpm axis as Y-axis and 32 on throttle pedal position as X-axis.

You will get four regions on whole map:

A: Rpm < 70 and throttle <32: Could be considered as firing up and acceleration to mid load. Although some values of torque is negative, it's because the rev is quite higher than idle and couldn't be achieved at engine startup. Therefore it must be result of deacceleration, driver reducing throttle opening, which means it's slowing down, no torque supplement required. The engine rotates due it's momentum.
B: Rpm>70 and throttle >32: You rarely encounter very high throttle opening, and very low rev. It must be driver closing throttle at very high throttle opening. So inorder to assist braking torque is negative here, except for near 32 % throttle and high rev.
C: Rpm<70 and throttle >32: This must be due to driver trying hard to gain acceleration at low rev, so torque figure are quite high and postive to assit acceleration.
D: Rpm >70 and throttle >32: This the peak end application that's why torque is again positive.
It should be noted that before 70 rpm torques are generally increasing and after that it's decreasing. It's because you don't need high torque at higher rev, since you are moving, rolling resistance now are less, compared to low rev. It's one of saving fuel and provide more rpm.
More revs could increase the exhuast flow rate, helping turbocharger to spool quicker.
It is used by redbull racing in formula 1.

"Torque maps were a hot topic in July and August 2012 when the FIA issue a directive and made some changes to the way teams were using them during the mid-season. But they are the single most important map for the engineers to use for reference when trying to make sure that the engine is optimized for a given circuit. A directive from the FIA around the time of the German and Hungarian Grands Prix closed a loophole exploited by Red Bull Racing and its engine partner Renault, to improve gas pressure from the exhaust by lowering the torque curve."

[dertobi]

why so complicated?!

in this example the map is Engine Power in kW, x axis is pedal percent, y axis is vehicle speed, cause it is an AT car. only on ATs you have the upper line straight values.
on MT cars the upper lines are increasing, as the y axis is engine RPM.

From these maps the ECM will calculate a Desired engine Torque(MT) or desired axle Torque (AT) taking the equation with P=2*pi*M*n on AT n will be calculated from NV ratio, vehicle speed and gear/axle ratio.

when you have the map in this form eg 215kw = 292Hp... that is what the car is rated from the manufacturer, or at least close.
with this map EVERYTHING in the desired Torque calculation starts.
so i highly recommend not to set it too high or you will mess up the whole torque caclulation of the ECU! unfortunately this is what 99% of people do.
you should set it to the engine power you want to achive and also in a range what the engine is capable of achieving.
leave the lower pedal values alone, I normally never touch more than the upper 3 or 4 lines.
of course you can tune throttle response with that table, but be carefull touching the very low values, as it can make the car uncontrollable.
when this Map is to low, the ecu will most certainly claose throttle to achive target power /torque goal.

on newer ECM mostly this map is desired axle torque(always vs RPM), and than it is calculated backwards to engine desired torque, these are a little more tricky to handle but the same rules apply. i Usually chage them by percentage (only upper lines)

on some AT cars there is a little specialilty: 100% pedal line is only reached in kickdown, so it is useful to set upper 2 lines the same

[iseebadpixels]

Any idea if this value is correct? (2.0 LTG)

[KillboyPowerhead]

Seems high if you're idling. Would think axle torque is engine torque * trans gear ratio * diff gear ratio. What does that number do when you're cruising, accelerating, etc.?

[iseebadpixels]

My diff gear ratio according to this AUTEL device is marked in red as unknown. It's an open diff. TCM chip is factory locked. The number does not change when accelerating.