Throttle Closing

[Morais24]

Have any of you been able to eliminate or at least limit the throttle close event that happens when boost peaks?
2014 SHO closes for 3 seconds as low as 33%

Tune is built off Metroplex's tuning guide - First time on dyno
Two full pulls - 4th gear
Temps were getting hot - Not enough airflow at dyno

I just hate the throttle closing like that, feel like the wastegate should be able to handle it on its own.


Kevin - 2014 SHO - DYNO.hpl

[The Bronze]

I just got back from my first run with the ETC modified and my results were let's say "less than stellar"! Looking forward to having your problem!

When I was looking at Metroplex's guide, I didn't see any information on the throttle body tuning, but have been working on the predicted TA vs. Effective Area inverse table to reduce these reductions as well.

[NickSezz]

TIP Actual is greater than TIP Desired so it closes the throttle. Missing an airflow limiter somewhere. Hard to tell without looking at the tune.

I also noticed that your Air Charge Temps, both IAT1 (pre turbo) and IAT2 (post intercooler) are very high. You running this car out in the desert?

If it has a stock intercooler, the focus should be on replacing that with a larger capacity unit.

[Morais24]

TIP Actual is greater than TIP Desired so it closes the throttle. Missing an airflow limiter somewhere. Hard to tell without looking at the tune.

I also noticed that your Air Charge Temps, both IAT1 (pre turbo) and IAT2 (post intercooler) are very high. You running this car out in the desert?

If it has a stock intercooler, the focus should be on replacing that with a larger capacity unit.

Wrong, TIP Actual is rising above TIP Desired because the throttle is closing. You wouldn't want to close the throttle and block throttle inlet if throttle inlet pressure is too high. You would do the opposite by opening the throttle.

What's really going on is these cars are programmed to use wastegate and throttle to control MAP pressures. Car did the same thing with stock tuning. I want to make the car use just the wastegate. Or at least limit how long the throttle stays partially shut.

Temps were getting high on the dyno - I mentioned lack of airflow in my original post.

[NickSezz]

Wrong, TIP Actual is rising above TIP Desired because the throttle is closing. You wouldn't want to close the throttle and block throttle inlet if throttle inlet pressure is too high. You would do the opposite by opening the throttle.

What's really going on is these cars are programmed to use wastegate and throttle to control MAP pressures. Car did the same thing with stock tuning. I want to make the car use just the wastegate. Or at least limit how long the throttle stays partially shut.

Temps were getting high on the dyno - I mentioned lack of airflow in my original post.

My apologies. Maybe I came off a little blunt in my post. I am used to tuning these while still letting the throttle control airflow.

[Bugasu]

Desired TIP controls the wastegate, Desired MAP controls the throttle. TIP Actual over TIP Desired will naturally close the throttle as your Desired TIP > Desired MAP (because of throttle loss).

If you want the throttle to stay open for some reason, you need to move TIP Desired out of range of what your wastegate can actually do. Of course the wastegate PID system will fight you for doing this, especially I-Term as it tries to ramp WG up for the TIP Error. So you need to recalibrate pretty much everything to get that to be happy.

And then, you have to make sure you're close enough to TIP Desired to not actually get an underboost code, or again move that out of the way.

As well, lets say conditions line up (it's cold, you're at sea level, etc) and now you suddenly can produce that TIP Desired. Now you're going to be overboosted and have more load than you probably want. The WG system is not designed to target a set airflow, its designed to target a set TIP that derives from an airflow, which will be constantly changing based on external conditions. Set boost tuning is inconsistent in the airflow realm, which is why OEMs don't tend to use it anymore, and the Ford ECU is not designed with raw compensations on the wastegate signal to do it. Can you hack it? Sure. But why?

Why not tune like the OEM and have both WG and Throttle helping control MAP and not worry about any of that, using the logic for its designed intent. Having two ways to control something is better than one, especially when one is fast (throttle) vs the other (wastegate). Why do you want only one way to control it?

[tbrtuning]

I just wanted to thank you for your detailed responses Bugasu. I have so many links to things you have posted bookmarked for reference. I've been tuning my first 3.5 and was a little concerned about the throttle closing so much compared to Focus STs I've tuned but this makes me feel a bit better about it. I just looked at some logs and with the exception of spoolup in a higher gear the small turbo on the Focus can't even reach the load I'm targeting so I guess that's why it never closes the throttle after the initial hit. It just seems weird to do a WOT pull only getting 40% throttle or something like that but it seems like they still make good power that way.

[96gt4.6]

I'm with Bugasu. All I worry about is that my MAP is staying around what i'm asking for boost wise. What the throttle is doing matters not to me, as if the MAP is there, the power will be too provided spark and fueling are correct. It's so much easier to let the ECU handle boost spikes on the shift/ect with the blade shutting out boost at times. But, each has their own method and there is more than one way to skin a cat. I tend to follow OEM methods as well.

[Morais24]

Desired TIP controls the wastegate, Desired MAP controls the throttle. TIP Actual over TIP Desired will naturally close the throttle as your Desired TIP > Desired MAP (because of throttle loss).

If you want the throttle to stay open for some reason, you need to move TIP Desired out of range of what your wastegate can actually do. Of course the wastegate PID system will fight you for doing this, especially I-Term as it tries to ramp WG up for the TIP Error. So you need to recalibrate pretty much everything to get that to be happy.

And then, you have to make sure you're close enough to TIP Desired to not actually get an underboost code, or again move that out of the way.

As well, lets say conditions line up (it's cold, you're at sea level, etc) and now you suddenly can produce that TIP Desired. Now you're going to be overboosted and have more load than you probably want. The WG system is not designed to target a set airflow, its designed to target a set TIP that derives from an airflow, which will be constantly changing based on external conditions. Set boost tuning is inconsistent in the airflow realm, which is why OEMs don't tend to use it anymore, and the Ford ECU is not designed with raw compensations on the wastegate signal to do it. Can you hack it? Sure. But why?

Why not tune like the OEM and have both WG and Throttle helping control MAP and not worry about any of that, using the logic for its designed intent. Having two ways to control something is better than one, especially when one is fast (throttle) vs the other (wastegate). Why do you want only one way to control it?

I was just more or less trying to start a conversation on the subject. I did not see a dip in numbers on the dyno during the throttle event however I can see where the rpm increase slows down. I by no means want to reinvent the wheel here, I was just trying to find out if it was something people were changing or accepting.
You have completely answered any and all questions regarding the subject and I appreciate the detailed and informative response.

[od_s2]

Bugasu, my class and I are tuning my highly modified focus st. We are running in to quite a few hiccups. Wondering if I sent you the files and mod list you could give us an idea of what is going on?

[Stevekreger]

Bugasu, my class and I are tuning my highly modified focus st. We are running in to quite a few hiccups. Wondering if I sent you the files and mod list you could give us an idea of what is going on?

can you post the build list,tune and scan files on here? I would be interested in seeing them, and what other people people have to say. would be great info!