You can think of inertia as the rotating mass. Force to change rotation speed is torque. The change or rotation speed is acceleration or decel of engine RPM. I think its mostly used in the ECU determining torque to correct Idle RPM speed. Thinks like flywheels and TQ converters weight can affect this, but usually the stock value is fine and the ECU PID controller can compensate fine with a 41lbft max and min correction.
Yes, I used to think these engine control systems measured torque by crankshaft acceleration, via the crank sensor. Lots of systems do measure crank accel, but for calculating tdc vs overlap, not measuring torque for ETC control, at least that's my thinking as of now, who knows.Originally Posted by murfie
Yes, I would imagine that crank accel is very important in idle control, esp in odd-fire motors, maybe some in these too, but not sure, seems they would idle good anyway, since they're even fire, but this one doesn't, with cams.
Is the torque in DD table an arbitrary number? Does the PCM simply read it, then lookup the corresponding load in the inverse table, then calculate fuel & air to give that torque? If so, they can't really be arbitrary, since the airflow & fuel requirements would max out very quickly, if I had too large torque numbers in DD table. I think this setup of mine is reading too high of torque for some reason, and throwing everything outta whack, then throttle closes, and torque goes down. Is there anything that would cause torque to read too high?
I spent a lot of time talking to whipple over one of their earlier gt500 cals and wondering why they not only lowered this, but they had lowered their DD tables as well even though the car was making substantially more torque and power... They stated they were doing this to keep them from throwing the wrench light - it's probably still low in mine because I forgot to put it back to stock after testing some idle fixes as their tunes idle very very nicely even with the heavier loads from the bigger blowers... It's also my understanding - and even partial confirmation that the DD tables on these things while used for torque calculations they aren't directly in control of torque limits, so stock or near stock ones work just fine even with decent mods... The other torque table on the other hand is what throws all of the wheel torque errors - I actually raised it through the roof and had a 1500Nm wheel torque error and had this car idling and driving the best it ever has - explain that one
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
The ECU is not using any sensor to measure torque like a dyno. Its being derived from a model. The model describes torque and load relationship at stoich, MBT, and STP. The current load is used and things like friction loss, pumping losses equations, and many other things are applied to obtain an estimated engine brake torque value. Inertia is one of these things used to obtain torque correction, not the actual torque, but a correction torque that needs to be applied to the torque coming from the model to either increase, decrease, or maintain RPM.
The DD torque comes from the pedal. It can be an used in either open or closed loop relationship depending on how the WOT is setup. Closed loop- DD torque values are used with the TB model to determine a final requested torque that really becomes a requested load. Open loop- torque value of DD table is requested, but only the TB model is used for a load request so it does kinda make the torque request arbitrary, until it hits a limit. The load request still goes through the torque/load tables as indicated torque is used to control everything. The DD table is not really an arbitrary number, even though it is more forgiving about the values than the torque/ load tables as its used in conjunction with the TB model that uses the MAF and airflow model to keep load in check. It should be at or near the values the ECU comes up with for an estimated engine torque. Usually values in this table are closer to what you see on a dyno. This will not only lead to better engine control, but also the closer they are the more direct your pedal will feel as far as control over the engine. Of course pedal feel is very subjective so it can be manipulated to make it feel as lazy or reactive as you wish.
You could have your injector data or inferred rail pressure jacked up and cause load to be reading high as the ECU corrects airflow for the fuel request. Most likely you are seeing high torque values as thats what you put in the torque model and the torque request. As an analogy just because your kids solar system model got the order of the planets and their relative sizes correct doesnt mean you would trust that the earth was only 10 Jupiters away from the sun as determined from that model. Just because that bit of information cant be accurately determined doesnt mean the entire model is wrong. If all you needed to know was how many planets there are, what their relative size is, and relative distance from the sun. It would give you more information than if there was no model. That is all the torque model is doing, providing just a little more information to the ECU, so that it can determine how to control the engine in more conditions than what the sensors are telling it.
Thanks for the good explanation!
In my case, I think I need to determine what is causing the high torque readings, as no need in trying to work around high numbers, that aren't correct. I very well could be running into limits that I will never see in the real world, with the torque reading correctly.
Murfie, do you think my torque values are high? I can't see any way a stock 14GT500 motor with a little overdrive, exhaust, & cams would make what torque values I'm seeing in HPTuners software. I have seen over 1200ft/lbs torque at times, over 2.0 load.
I will put the DD table back stock again, and work from there. I am using the Injector data from Injector Dynamics for my injectors from them, and airflow data for my TB that I have found online. I will go back over make sure what inj I actually have, & ensure the data is all correct again, to be sure. These aren't anything outta the blue, just regular bolt-on setups lotsa guys have ran, so I should be able to get this going good, with correct info somehow.
Before any other modification to your cal, I would work on the MAF transfer to get it much closer. If the MAF is off, it will impact your load values.
2012 Mustang GT with S/C
4Runner with S/C
Turbo/NOS Hayabusa - 320RWHP
It's pretty close, or was, before I went to experimenting. Last couple flashes it's been going lean. I'm gonna backup some & go again.
Today, I spent a few hours with this car, went over the inj values, double checked the actual inj it has, and looked up the ID specs, and reentered them, I had done a few things wrong when I first entered the data, once I fixed all that, it runs way better down low & idle. After that, I took the Tb apart, made sure what it is, and that it's not binding or anything, & reinstalled. I'm still not going WOT, but it runs good, getting a torque reduction lean, gotta get more fuel to it. I've been logging the maf period, adding fuel where it goes lean, seems to be working, but it got late, had to stop. I'm thinking one limit is it's lean, shutting throttle, once I fix that, should get better.
Wondering how the sensor I posted plays into this fuel calc? Especially since the temp sensor that's integrated into it is just sitting on top of the motor, getting heat soaked. Is this IAT1? If so, that's not gonna work very good
You shouldn't be hitting it, but don't forget to raise your inj dc limits - common limiter to hit...
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
Ok, I don't think I've seen that to be adjusted, can you recall where it's at in the software?
Have you put in the correct trans gear ratios yet?
Pretty sure I did, I'll look tomorrow to make sure. I don't think it's made any difference.
I've been noticing, it will go into the trans shift mod as soon as I get the torque reduction lean error. Maybe one is causing the other.
It's in the fuel injector section. Towards the bottom. It usually causes me headaches.
Yes, found it, but it's already at 108% stock. Haven't touched it yet.
screenshot.jpg
Go up to around 200%
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
Ok, will do. I assumed 100% was totally on, maybe not on these?
It seems to lean out at higher rpms, causing throttle lean torque reduction, so Ive gotta get the lean fixed first & go from there. Fuel pressure is 25-75 psi, is that normal?
Ok, tried 200% inj dc, no different, going lean, also tried upping the alternator voltage, no difference.
I'm getting fuel pressure dropping from 72psi to as low as 46psi, this isn't correct, right? Never saw an efi system vary this much. This car has a KB BAP, and checking it with a voltmeter I get 20v going to both pumps idling. I assume it's working properly, so I guess I have a bad pump, or pumps?
Here's a log of the last run, logging fuel pressure.
3-19.hpl
voltage shouldn't be that high at idle - voltage should go up with boost / it may just need adjusting for the cams, but you might want to check everything with a volt meter and a pressure pump of some sort...
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
This BAP is wired to be on 100% of the time. Looking at their online directions, it should have a switch turning it on, this ones on all the time, no switch, the wire thats supposed to go to the switch is taped up.
Any input as to what my fuel pressure should be, logging with HPTuners? I've read that it's not accurate, but seems to be
To update;
Took tank down, one of the two fuel pumps are bad. I will replace & get back to tuning.
The BAP is installed before the fuel pump controllers, so I had 21v going to the pump controllers, not necessarily the pumps. I think Lund was regulating the pumps in the tune, to keep the BAP from sending too much voltage to the pumps, vie the pump controllers, when not needed, then when boost came on, pumps see the 21v from the BAP. Since I got rid of the Lund tuned pcm, I had no idea what was happening, and how this setup was configured, and burnt the pump up. If I'm correct, I'll need to also tune the fuel pump settings, when I get the new pump reinstalled. Anyone else seen this before?
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