Low Throttle Opening Issues - SCJ TB 2008 GT500

[Blown383]

Hey everyone. I've recently added a SCJ throttle body to my 2008 GT500 and have managed to make it drive pretty close to how it was on the stock TB. Snappy throttle like stock. Idles smooth and no on/off feeling. I've been using the Effective Area calculator but I cant seem to get the low throttle opening to act correctly. Say I'm in a parking lot or pulling out into traffic and I'm off the clutch at near idle and go to accelerate. The throttle will open then close then open back up again. It's been some work to get it in a log but I finally managed to do it. Log attached below. See 18:01:53/6:01:53 for the spot in question.

I've been going off of caniggia's thread and LaSota's book about adjusting the predicted table using torque error. If the torque error is positive, lower the value. If the value is negative, add to the value. Extra step I added is using the calculator to update the Effective Area table, as it *should* be the inverse, right? So far, this has worked rather well and my torque error, except at idle and low opening, isn't too bad. I have not touched my torque tables yet as I am not 100% sure on how to adjust those. Probably using torque error as well?

When the car goes to close the throttle, I see torque error skyrockets to 3000+ and ETC Vacuum also skyrockets. I don't know what I need to adjust!

Car has upper pulley, intake, full exhaust and now the TB. Idle torque error is around 250-500. I tried getting this lower but haven't been able to with the throttle tables. I ended up adding some airflow to the idle airflow tables and that stabilized the idle for the most part. Any suggestions are welcome. Trying to learn proper throttle tuning to apply at my shop! Thanks.

18-03-28 18-24-26.hpl
08GT500-9.hpt

[MRRPMBRP]

I made a histogram so I had absolute load on left column, rpm across top, and throttle error filling in the boxes. In this way, it will populate error in exactly the right place to adjust the torque tables. Put the same values in torque tables, and rpms, so they coincide. If negative numbers, take away torque, if positive, add torque, to your torque tables. Then calculate inverse with calculator. I've been working on my 14 GT500 lately, and came up with this, so far, throttle errors go away, away as well as ipc errors. No adjusting of throttle tables or ipc, or throttle inverse. I'll post a screenshot later on. Maybe not the correct way to do it, but seems to work for me.

[Blown383]

I figured that the airflow model of the TB has to be correct before I modify torque tables. Perhaps the best method is get it close then fine tune with torque?

[CCS86]

Interested in what you guys come up with. I'm in sponge mode right now, soaking everything up.

[MRRPMBRP]

On mine, I have known throttle settings, as I have a Ford Performance one. You should also be able to get correct settings for yours, if it's Ford.
I have tweaked mine some, but not much at all. I had throttle errors, if you make the throttle settings lower, the throttle is limited by the opening in the table, so it makes sense to just adjust torque to where you don't have throttle errors, or IPC errors.

[Blown383]

I haven't been able to find the FRPP SCJ throttle data anywhere. People don't like to give that one up lol. I found data that was close that I used as a baseline here on the forums. It's close but not 100%.

[MRRPMBRP]

Here's my graphs file I use to tune torque tables. Use the one at the bottom

table torque tuning.jpg

2014_GT500graphs.Graphs.xml

[MRRPMBRP]

Which throttle exactly?
I found FRPP mono blade, and FRPP twin 65mm on here

[Blown383]

Monoblade. The data isn't 100% perfect. Using the data on the spreadsheet on this forum, the car didn't want to idle well from coast down and did the whole throttle closing thing at 1/2 throttle. It also felt sluggish and slow to respond. My modified tables based on that made all of that much better, besides this small thing at low throttle inputs and high IPC Torque at idle. Occasionally I'll get a bit of a bounce on a coast down with the clutch in but I think its related to the high IPC Torque Error at idle.

[MRRPMBRP]

Mines perfect coasting down, only throttle problem i have is an occasional flare up, not sure whats up w that. I havr FRPP twin 65 though.
Idle issues i was having had to do with incorrectly entered inj data, once i got that right, it was way better. I also have l&m nsr cams, a lumpy idle, but i have , it pretty good.
Do you have a stock dd table?

[Blown383]

Stock DD table. Stock injectors. I got a monoblade because I want to learn how to tune it haha. It's really close. It really is. I'm just lacking fine tuning.

[MRRPMBRP]

Log where its giving trouble & post the last table i posted. I cant read a log for a few days, but i can look at screenshots

[Devildog1325]

I used the scj monoblade data that has been provided on the forum and I think there is one in the repository. Mine drives like factory I cant tell any difference between it and the stock TB but I adjusted my torque tables. Look at Bill's recent thread explaining fords torque system and it would also help you to read some of Murphy's threads about this subject. After you get those tables adjusted you can fine tune the throttle body model. I cant open your file right know but the etc calculator likes to put zero's in the lower end of the throttle body model and can cause decel and lower throttle body angle problems but I would stick with the supplied data.

[Blown383]

The data on the forum has 0s in the lower end already. So is tuning torque then the throttle tables the correct way to go? Seems counterintuitive to do it that way because wouldn't torque be incorrect considering it doesn't know how much air is entering the throttle body?

[Blown383]

I put the throttle tables back to the original values and have started to change the torque table. The low RPM throttle close still occurs and now at 50-60% throttle, the throttle like to go nearly wide open when I'm not commanding WOT. Screenshots and the log below. I must be having a hard time getting my head around this. I understand the system commands a torque based off of driver demand. I guess I'm not getting what happens after that and I am not seeing a real solution to fixing this. I understand the scheduled torque and everything. I just don't see why scheduled torque falls off a cliff when it closes the throttle and why it suddenly doubles the throttle angle when I am over 50%.


Capture2.PNG
Capture3.PNG
08GT500-10.hpt
18-03-30 20-28-02.hpl

[murfie]

Looks like you are using the beta calculator.
Seems the stock load values get a little smoothed by it.

Beta calc load .PNG

If you look at the Stock tables you can see the inverse relationship. Where one goes up the other goes down, and vise versa.

Stock load.PNG

I would use a spreadsheet and get your torque values inline with the beta calculator, if you are going to use it. Or use some other way to keep the inverse relationship. You don't want both to be going down or up at the same time, or one moving with out the other moving at all. Those conditions means airflow is either increasing or decreasing according to the model, but load is not. This translates to an unwanted RPM change to make everything happy.

Load to Torque values.PNG

inverse calculator example.xlsx

[Blown383]

In your example spreadsheet, how did you calculate how much torque there is per point of load? Seems like the calculator needs some work to be truly useful. I'll try out my new inverse table in the morning. *fingers crossed*

[murfie]

I multiplied the axis values together to get a reflection point. I then take that and divided it by the load to get the inverse torque value. It could be done the other way divide it by the torque value and get the inverse load. I just correct the torque values and not the load values, so thats why I do it the opposite way from everyone else.

I think absolute load is pretty accurate if fuel and air models are correct and makes a good known value to correct things from. Being as the torque values are a representation at STP, Stoich, and MBT, I feel correcting load from torque values is purely guessing unless you come up with some elaborate pumping loss equations for calculating cylinder pressure and correlating to torque and correcting that value for temperature/baro, fuel, and knock limited spark. You could have fuel close enough and keep it at stoich(no PE), use a extreme climate control room and dyno, and race fuel to obtain true MBT values to omit the last correction.

[Blown383]

Hmm. Based on that, would you say that correcting the inverse/load table then calculating the torque table is the way to go rather than the standard method of correcting the torque table then calculating a load table? Then using the calculator isn't the way to go at all. I haven't had any luck with it at all. This could be as simple as logging load in a inverse table histogram then dividing that table by the table in the tune to get a correction factor to apply, multiply that to the table in the tune, then calculate a new torque table.

Is there a difference between Air Load and Absolute Load? I've always seen the values nearly agree with each other and have always used Air Load for the majority of my tuning.

[Blown383]

I tried calculating it using a speadsheet and making sure it was an exact inverse but it made the car even worse at half throttle. Screenshot below. You can see how the throttle yanks back when I'm holding a near constant pedal position. Capture4.PNG