I think I need TIAP to properly tune my L83 turbo (part throttle)

My problem seems to be that the computer is opening the throttle blade too much during part throttle, which causes very poor shifting. My torque tables are stock, BARO sensor is broken out, MAF is calibrated, and VVE is pretty good.

My theory is that for a given cylinder airmass demand, the computer is opening the throttle too much, because it does not know it is under pressure flow. Low pressure ratio (0.8 and below) and WOT everything is fine. It is just during part throttle that the blade opens too far, actual torque goes way above driver demand torque, and the trans does not like this, so it pulls more timing during the shits.

I seem to have found a possible work around by jacking up the VVE tables in the boost sections, to over 6000, which is super high, but it uses MAF only in those areas so the fueling is fine. This makes the computer think the engine is super efficient and does not need much throttle blade to meet the airflow demand.

The other thing I tried was changing the map sensor config to TC-MAP-TIAP-BARO, when i first did this and started the truck the throttle did not work at all and it gave a BARO sensor code. So I dug up the ECU pin out for the only factory turbo car I could find with a E92 ecm, the ATS-V, which has as TIAP and separate BARO sensor and wired a BARO sensor into my truck.. it did not throw a BARO code, but the throttle still did not work. I assume this is because it was referencing a bunch of hidden tables in the ECU that are zeroed out for my application.


I know there are plenty of boosted cars with breakout sensors, does no one else have this problem? Do you all just turn off shift torque management as a work around? or crank up the base spark table? Both of these options I would rather not do...

I understand that for the Gen 4 stuff, HP made an OS that prevented BARO update, which I think would be a good fix for this. I could breakout the BARO from the MAF, wire up a 3-bar sensor, then put it back in the charge pipe and have better throttle control.

Has anyone pushed HPtuners to turn off BARO update so we can run a proper TIAP sensor?

In just finishing my cammed and supercharged L86 A8 at 8psi truck I found the torque tables to be very low in respect to what the engine was actually making. The reported torque was lower than the dyno reported torque at the tire which is impossible. That is what got me onto modifying the torque tables. Once I got the MAF and VVE dialed, within 5%, I moved to the airmass and map torque tables. I set the rows in my airmass table to 1600 and my map table to 160kpa. From there I found were the engine ran at WOT in both tables. For a test I multiplied the entire row it was running in and everything above it by 1.20. From the row it was running in at WOT to 2 rows above idle area i interpolated straight up leaving all the tables linked and idle areas alone, extrapolated and then calculated the new tables. That made a huge difference in how the throttle body reacted to pedal input, trans shifting and even made the lumpy cam idle better. In the beginning the throttle would slam wide open right after shifts creating this push feeling at part throttle. After a few times of adding to the virtual torque table and some DD table work my throttle body basically follows my foot and the blade movement after shifts is minimal. The trans shifts better and drive ability is awesome. Once i got control of the TB i was able to put more realistic numbers back into the DD table and was able to work on how aggressive my demand might be at any given speed and pedal position. What also happened was my MAX torque moved up and now the only time the things go above the MAX torque is when im above 90% pedal therefore requesting the torque needed from going into boost. After all of this my PE requirements changed. PE is set to 70% pedal and 90% torque as those are where the requested torque is high enough to open the TB enough to allow bypass valve to shut and start making boost.

If you put your tune up I can show you what i am talking about.

I have an email started to HP support about the Baro update as it for sure makes tuning the VVE more difficult. I would like a baro update patch like GEN4

Here is my latest tune.
Attachment 93254
I think there are some key differences in our setups that make tuning different. What type of blower is it? PD or centri? and I think the cam also makes a big difference.
My theory for the torque tables is that the stock ones should be close if you don't change the displacement or cam on the engine. My torque tables seem pretty reasonable or even a bit high. You may remember from a previous posts that I raised the torque tables to keep the throttle blade from opening too fast, but the real problem seemed to be that my VVE was not as good as I thought, and I have since gone back to stock torque tables. Also, raising the tables meant I need to raise the DD, and this caused other issues with traction control and cruise control. So now my torque tables and DD are stock.

The shifting problems I am having are also much different that the surging you describe. When my VVE was bad and my torque tables were higher I was getting the surging you were describing. Now with my VVE better dialed and using stock VTT the surging has gone away,.....but I still have the problem, that after a shift, the computer will continue to pull timing for nearly a full second after I feel the shift, and then the power comes back in. In the log below, at the 30 second mark, is a good example of a bad shift, you can see how the actual torque jumps around from immediate to predicted... My thought is that the predicted torque stays low because that is the power the DD wants, but the actual torque goes higher because the throttle body is letting in too much air. If I could keep the throttle blade from opening so far then actual torque would be down around the predicted value. This goes back to my theory that the airflow equations for the throttle blade won't work properly if it doesn't have a TIAP sensor.

Attachment 93255

My setup is a magnuson supercharger so yes, very different, obviously. No matter what, it is about working with what we have to control torque demanded and torque delivered and unfortunately we are missing lots of tables and definitions needed to properly calibrate these.

I have watched Greg Banish's GEN5 stuff a dozen times and that unlocked a lot of new info but re-iterated the fact that both air models need to be correct. If you have not, spend the time and money to check them out, lots of money but worth the info.

I personally think having a stock OS that does not understand boost at the core will always cause issues that will require a certain amount of lying to the ECM about specific things to achieve the behavior we are after with a fair amount of compromise needed.

I also believe the factory torque tables, or at least how HP lets us view them, is flawed. If you look at a stock torque table and how jagged, rough and unrealistic they are doesn't make sense as things should be smooth and progressive. Not to mention even stock my truck on the dyno put down numbers at the tire, in 6th gear, that were higher than the reported torque in the scanner, I don't think that should be possible. Now of course trying to get a low to high RPM pull on these 6, 8 and 10 speeds is a real PITA.

In your case i think some changes to the trans in the timing of TM might help with the long TM on shift. Also some torque table and VE changes would help.

This is only my opinion based on what I have been able to achieve on those I have done and also my personal vehicle.

Attached is something I would try, to see cause and effect. I gave you some changes based on another truck I have done. I left you DD alone except added to the top row just to see if what the TB does.

Thanks! I really appreciate your time and help! I will give this tune a try and see how it goes.

I have Greg's Video, and yes, it is very good. Getting the air models very close is key, but I wish he would show an example of boosting a non boosted OS car.

Give it try after comparing and looking at it. I didnt change much, really a cause and effect test. Im still working on the nit picky, mid to moderate throttle driveability on my personal vehicle and have lots of fuel burnt getting to what I would consider absolute best. The inner perfectionist has to learn to compromise.

His supplement online video on torque table editing answered a lot for me. Really it confirmed my thoughts on things.

The days of quick and easy tuning are over. These torque based systems take time to get dialed, especially when dealing with driveability and an automatic.

I can tell you this with certainty, once your demand sits on top of actual things really start to behave and become much more accurately predicted therefore delivered.

I looked over the tune changes you made and figured it was worth a try, so I loaded it up. It made some improvements but I still had the same throttle control problem. I was convinced that the incoming air pressure was throwing off the throttle airflow calcs and it would never be tuned right without a TIAP. So I went back to trying the TC-MAP-TIAP-BARO and it worked this time! I think the difference was that this time I left the "Forced Induction Type Fitted" to none, instead of setting it to Turbo. I can't believe how good the truck drives now. I don't even feel most of the shifts and the log shows it is finally properly controlling airflow coming into the engine.

For anybody else that wants to try, here is a summary of what I did to convert a NA-MAP-TIAP to a TC-MAP-TIAP-BARO.
1. Install a 3-bar MAP and adjust the MAP characteristic.
2. Breakout the TIAP from the MAF, install a 3-bar sensor (same as map), adjust the AAP1 characteristic, and install it in the boost path ahead of the throttle.
3. Pin a 1-bar sensor into the ECU to be the new BARO. The two pictures below show where to pin the wires and where wire connect into the sensor.
This is the middle connector on the ECU. The larger red and white wires on the left are the new pins. I just pulled out the blue plugs for these holes and stuck the new wire in, seems to make good contact.
The black wire between the new red and white is a 5v reference, I piggy backed it to use as the reference for the new BARO sensor.
Attachment 98494
The next picture shows the orientation of the red, white, and black wires into the sensor.
Attachment 98495
4. Disable the BARO sensor tests. Under Engine Diag > Airflow I maxed out the P2227 correlation pressures and the P0101 ECT values to stop those tests. It seems that with the new setup the ECU would still estimate BARO and get weird results which would cause a CEL and pressure ratio issues.

Way to stick with it and make it happen. Glad it is working like you want. Nice work!!

Care to share an after log? That would maybe help to see the cause and affect of what you did using the above log and a new one.

Here is my log from last night. It has much better throttle control, and Driver Demand Axle torque stays above Actual Axle torque.. most of the time.
Interesting that Immediate, Predicted, and Actual torque all go way above Max Torque without issue, and even above Peak Torque, where it seems to close the throttle.
I think my next step is to get the VVE dialed in as close as possible. I think most all my remaining issues will be fixed with a good VVE. I started to bump it up in the rpm/pressure ratio ranges where DD torque exceeded actual torque and that closed the throttle a little to keep things in line better.
After the VVE I may adjust the torque tables if I think I need to.