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Ok so I'm starting to make some strides on 15 mustang throttle body tuning but despite spending a lot of time looking over files, looking up parameters in vision etc I still do not fully understand idle and start up airflow on these controllers.
Is there anybody with a better understanding of how the system works and how to modify idle and start up air control?
I did find a torque table a while back while I was playing with ghost cam stuff that seemed to have an affect on idle
FNTQE_FRC_COLD
I actually requested Eric to add it but I know how busy he is.
Still, I hate the try this and check methology to tuning. I want to understand the system and calibrate it properly
what kind of setup is this on?
what TB etc
This is just a roush with gt500 tb but I would like to start venturing into some mono blade stuff as well and realize that right now I do not understand how the tricore controller calculates desired airflow/ tb angle at idle
Post the tune and more info on the build
So after playing with it a while I found that modifying the torque tables around idle affected idle control. Still not sure that this is the correct way to go about this. I would think there has to be a look up table somewhere that has torque desired for idle.
I was really just trying to have a generic discussion about idle control on 15+ mustangs since there are no longer idle air tablesQuote:
Originally Posted by andrewzpsu
I found that the MAF needs to be dialled in spot on at low airflow or cold start can be a pig
I'm guessing by the lack of responses no one really has a grasp on this yet.
All idle values are not defined as yet. I have queried hp about this.Quote:
Originally Posted by curt@injected
I've been working on it the last couple of days. I've made a little progress but still have a ways to go.Quote:
Originally Posted by 4wheelinls1
One thing I have learned thus far. There is a source value for torque reserve at idle. If you raise these values at all it hits a combustion stability limit. Meaning there has to be another table limiting the reserve functions. This is also why these tables seem to do nothing. This is probably insignificant though since I do not believe using the reserve values is the correct way to add idle torque. There is also a DMR that can be monitored for idle torque control that shows pid control at idle adding and removing torque which may be similar to what ipsibr was on the old air based idle systems in the copperhead and older stuff. I also did find part of the equation the pcm uses to calculate needed idle torque which does include engine torque losses so the table I defined earlier may not be the worst way to increase idle torque. It's that time of year where I have a little extra time so I'll try to keep going.
I am working on it.
PS: It is complex. There are a ton of things that are related to this, so I have to decipher what you guys need to be changing.
Yes the pid control for idle is complex. It uses calculations from the pid controller, ff torque, engine inertia and a torque offset each of which is based of a complex equation but I'm still trying to understand the starting point for torque and it may come from a combination of calculated inertia torque and calculated engine produced torque derived from the torque tables. There has to be a starting point for the first pass but this is one of my first endeavors into understanding some of these engineering papers.Quote:
Originally Posted by Eric@HPTuners
We need a simplified calibratable parameter to tell the engine to produce more torque at idle. This will come more into play as we start adding cams and stuff to 15's
So after a couple of days of reading, data logging, and trial and error this is where I'm at. Anybody with additional input feel free to chime in.
The pcm uses a complex series of equations to determined torque needed for the engine to run at the desired idle speed. Taking into account engine torque losses, accessory torque losses, transmission torque losses etc. These values all combined are what the engine needs to idle. It then takes these values and uses the torque tables to back into airflow. Kind of an over complicated way to go about it if you ask me but hey Ford engineers need to keep their job too.
So the question for us is what is the correct way to calibrate this system in a situation where we may need increased airflow at idle? Obviously the 100% correct way would be to model it the same as ford did from the factory but realistically most of us do not have the resources to make this happen. So we can either tell the pcm(via torque tables) it is making less torque in the idle region or we can tell it that total torque needed to make the engine run is higher.
This table FNTQE_FRC_COLD is a model of engine frictional torque loss. It shows torque loss based on ect and rpm (I believe. Haven't looked at it in a while). By increasing torque loss in the idle region you can make the pcm produce more torque at idle because it thinks it needs more torque to run there. In some ways this is a cleaner way to go about it. It is neither accessory or transmission dependent. It allows us to add torque based on both engine speed and coolant temp and only requires changing one table. Whereas modifying the torque tables requires quite a lot more work. But in theory which way is most correct? Downside to using the frictional torque table is I can see the potential to hit additional torque limits as we are telling the engine to produce more torque. I guess this is probably dependent on the situation.
If I get a chance tomorrow I would like to play around with this a little while data logging the dmr I found for the idle torque pid to see if we can use the dmr and these tables to find the correct torque value for idle without having to guess.
I've got it all worked out. In the process of adding parameters to the scanner and the editor. I will post up once its ready.
Just FYI finally had a chance to see if this idle stuff works. Seems to work pretty good. Was able to use the DMR's and the friction torque model to go from adding 30 ftlbs to within 1 or 2 at idle on one.
Thanks to Eric for helping me move this forward. Now we have a little better understanding of the torque model at idle in S550's. Hopefully this helps some people out.
Glad it worked out. I only added the stuff to the 15+ V8 Mustangs, so if someone needs this stuff on another vehicle, just email support.Quote:
Originally Posted by curt@injected