Tinkering with the throttle map

[NSFW]

Here's the throttle map from my stock ROM:

 

http://i193.photobucket.com/albums/z151/Legacy_NSFW/ThrottleMap.png

 

When I first test-drove a Legacy, I thought the throttle response felt weird. I'd give it 1/4 throttle and it responded like I gave it half throttle. (See also.) It took me a while to get used to it. After seeing the maps that govern throttle response, I got sorta curious about whether I could make this car feel natural (where "natural" to me translates to "more like the car I knew and loved for the last 15 years or so, only with more power).

 

And what better way to get familiar with the reflashing process than to mess around with a table that alters the way the pedal feels, but not the way the engine actually behaves?

 

So, the map in my car is very simple now - all of the columns are the same from top-to-bottom, and each column's value is the throttle pedal percentage x 3.2 (so it increases linearly to 320 at 100%).

 

The good news is that twitchy / ambitious nature of the throttle response is pretty much gone. On the other hand, the pedal feels kind of numb below about 40%. No surprise, considering how drastic the change is.

 

I've been driving with the stock knee-shaped table for a year and a half (since I got the car), and that felt all wrong to me at first. I went for a short drive and the new map almost felt normal again. I think I might be happier with something halfway in between linear and stock, but I'm going to take a week to get used to this and see how I feel about it.

[spiralsmurf]

well a cable operated throttle is not linear, so making everything identical doesn't really solve it. i feel the same way as you though, the stock throttle mapping is terrible. with my act flywheel and light crank pulley the engine is very responsive but the pedal still sucks. when i get my tactrix cable this week i will also mess with this and post my results

[qikslvr]

Why not just find an STI ROM and copy over the throttle tables from it. That is what most tuners do.

[SeeeeeYa]

^ plus, I use my throttle tables to assist in my 5EAT's shifting over 7k, and protect against over revving. For example, after rescaling the rev column to include 7200, I put a 25% value in the 7200 row. This way when it is cold out and my car wants to shift over 7100 the ECU sees 25% coming up during interpolation, reduces throttle appropriately, and the transmission (almost said tranny then remembered all the sickies on here ) shifts as if I instantaneously lifted my foot. Works great.

 

One might question the 'need' to rev over 7k, but my car still has 19-20psi of boost and is making great power until, and I'm sure after, that.

[hutru01]

^ Interesting....does it feel like you are in a manual when it reduces throttle at 7100 RPMS?

[SeeeeeYa]

^ Interesting....does it feel like you are in a manual when it reduces throttle at 7100 RPMS?

 

Actually, the shift is so fast, and things are happening so quickly that I'm usually just giving all my attention to driving. The need for this only occurs in first to second shifts, in 30'sF temps. Otherwise my IPT 5EAT shifts @7k +- 100rpm depending on temps (read power output ).

 

Nevertheless, I did this from the standpoint of ensuring I didn't over rev, for any reason...... although when my rear axel broke it felt like it shut off when it slammed into the 25% region instead of anticipating it. It is a 'softer' option than the rev limiter alone.

 

And as for it feeling like a manual.... I much prefer this transmission now over a manual. Side by side with a manual, all other things equal, so-called power losses included, I'd bet on me .

[hutru01]

^ Gotcha, mine shifts above 7000RPMs in Sport Mode everytime, that I know, but its really clean. (Just not getting the boost levels that I would expect from the SZ55)

 

In due time....

[Spec B]

Why not just find an STI ROM and copy over the throttle tables from it. That is what most tuners do.

 

I felt no difference in throuttle response with my TDC stage 2 map.. Do all tuners do this?

[Infamous1]

I felt no difference in throuttle response with my TDC stage 2 map.. Do all tuners do this?

I would suspect TDC would but most wouldn't as they are not familiar enough with LGT platforms to know this should be done. This is unless they owned one as TDC did.

[SeeeeeYa]

I felt no difference in throuttle response with my TDC stage 2 map.. Do all tuners do this?

 

Back when I was using TDC's eMaps he used the more aggressive throttle tables in some, but not in all. It was a requested item, later included in all maps, then reverted to an as-wanted feature after some people complained about the, to them, twitchy throttle response.

 

I've done both. For some time I've been more satisfied with the 'normal' table instead of the STi one. To me, it provides for a little more deliberation between normal to semi-aggressive driving and flooring it. With the STi-like throttle table it is very easy to forget the exact foot response during some normal, but necessarily brisk, driving maneuvers. Instead of quickly crossing a busy intersection, for example, one roars across. The popo frown on this .

 

Another thing that the STi tables affect is gas mileage, something I am more aware of these days.... gas from the Chevron yesterday cost $4.199gal . Contrast that to what gasoline cost me when I was a teenager......... $0.199gal . We could drive all night on a buck. Thus, the normal throttle table lets me exploit the dual nature of my LGT better than the STi one.

[2005garnetGT]

whenever anyone else drives my 04 STi-mapped LGT they always bitch and moan about how twitchy the throttle is...

[NSFW]

Why not just find an STI ROM and copy over the throttle tables from it. That is what most tuners do.

 

I am not trying to get the same results that most tuners are trying to get.

[Alighieri256]

(so it increases linearly to 320 at 100%).

 

Just a thought. You might want to move the 320 to come on earlier. There's no guarantee that the pedal position sensor ever reaches 100%, so you might not be opening the throttle all the way.

[NSFW]

well a cable operated throttle is not linear, so making everything identical doesn't really solve it. i feel the same way as you though, the stock throttle mapping is terrible. with my act flywheel and light crank pulley the engine is very responsive but the pedal still sucks. when i get my tactrix cable this week i will also mess with this and post my results

 

I was not expecting to be done with this after one flash... a linear shape seemed like a good thing to try though, and like I said, it's likely that I'll wind up some something in between. There's also a second table that turns the values from this table into actual throttle opening angles, and it's got a funny shape to it as well. So linear here doesn't mean linear overall.

 

And if linear somehow ends up feeling better than the mechanical linkage in my last car, then DBW FTW.

 

I suspect the second table affects the relationship between the cruise control's output and the throttle opening, so I'm not inclined to mess with that. Cruise control works just fine as-is.

[NSFW]

Just a thought. You might want to move the 320 to come on earlier. There's no guarantee that the pedal position sensor ever reaches 100%, so you might not be opening the throttle all the way.

 

It goes to 100 at full throttle, I checked.

[Infamous1]

Just a thought. You might want to move the 320 to come on earlier. There's no guarantee that the pedal position sensor ever reaches 100%, so you might not be opening the throttle all the way.

Yes there is a way it is called logging, it always reaches 100%

[Alighieri256]

Yes there is a way it is called logging, it always reaches 100%

 

It's not necessarily going to be that way for all vehicles, and not necessarily going to remain that way over the full life of the vehicle either. That's why the stock mapping on TBW vehicles has full throttle coming on well before full pedal. My intention was simply to make sure he was at least checking.

[Infamous1]

It's not necessarily going to be that way for all vehicles, and not necessarily going to remain that way over the full life of the vehicle either. That's why the stock mapping on TBW vehicles has full throttle coming on well before full pedal. My intention was simply to make sure he was at least checking.

ANYONE exploring and modifying the rom should be logging. Throttle angle just happens to be one of the required parameters that would need to be logged for the logs to be worth anything.

[Alighieri256]

ANYONE exploring and modifying the rom should be logging. Throttle angle just happens to be one of the required parameters that would need to be logged for the logs to be worth anything.

 

I completely agree with your statements. As I had said, I was simply trying to offer a helpful thought. The PPS is a mechanical rheostat, and as such, its impedance characteristics will change over time, add to that the fact that there is natural variance from one unit to another, and it just makes sense to add a little fudge factor to the upper limit.

[boostsr20]

whenever anyone else drives my 04 STi-mapped LGT they always bitch and moan about how twitchy the throttle is...

 

I didn't like it on mine. Went back to stock. To me it takes away from the feeling up top.

[Kaos22B]

I also adjusted mine to be much more linear. The stock mapping leaves much to be desired, in many aspects. The car drives much more smoothly now, and doesn't make you look like you're driving like an ass out of every light. Gas consumption is lower now as well!

[merchgod]

Not clearly mentioned in the original post, you need to make sure you tune the "Requested Torque (Accelerator Pedal)" and "Target Throttle Plate Position (Requested Torque)" together understanding their relationship in order to get the desired throttle mapping. You can also log "requested torque" and "target throttle plate position", which were added in the dec 07 def update (which is also included with romraider 0.5.0b).

[NSFW]

I'm aware of the other table (mentioned in the middle of post 14 in this thread) but I am not really trying to get a "desired throttle mapping." I'm just trying to alter the way the pedal feels. Of course that implies changing the throttle mapping but what I mean is, I don't have a preconceived idea of what I want the pedal vs. plate angles to be, I just know that I want it to feel more linear and less steep-then-flat.

 

But while you're here... my only guess as to why there are separate tables for pedal-to-torque and torque-to-throttle is that the cruise control signal gets routed to the second table, and not the first. Does that match your understanding of these two tables? Are there (other?) values that go through one table but not the other?

 

Thanks!

[Boostjunkie]

well a cable operated throttle is not linear, so making everything identical doesn't really solve it. i feel the same way as you though, the stock throttle mapping is terrible. with my act flywheel and light crank pulley the engine is very responsive but the pedal still sucks. when i get my tactrix cable this week i will also mess with this and post my results

 

Dood, if you wanted your throttle mapping to be changed you only needed to tell me and I would have changed it for you. I did use the drive-by wire to close the throttle right before fuel cut to give you a softer redline, but I didn't know that you wanted a change to the throttle mapping. No worries, I know that you are a serial tinkerer and can take care of it yourself

 

BTW, hear anything back from Coolingmist about the pump?

[merchgod]

I'm aware of the other table (mentioned in the middle of post 14 in this thread) but I am not really trying to get a "desired throttle mapping." I'm just trying to alter the way the pedal feels. Of course that implies changing the throttle mapping but what I mean is, I don't have a preconceived idea of what I want the pedal vs. plate angles to be, I just know that I want it to feel more linear and less steep-then-flat.

Well, even if you have a general idea of what you want, you still need to tune both tables as a set (or at least have an idea of what the target throttle plate position table looks like). For example, with the usdm 07 sti, there would be certain throttle plate angles that you could not achieve in the midrange (something like 30-70%) unless you modified the target throttle plate position table. That is, the factory tune can have some retarded targets in this table that may not allow you to do what you want to do by only tuning the requested torque table. I know you are aware of both tables, but for the sake of others that might be reading this post, it is important that this is stated clearly -> the target requested torque from the "Requested Torque (Accelerator Pedal)" is used as an input (x-axis) to the "Target Throttle Plate Position (Requested Torque)" to determine the target throttle plate position. The ECU will then attempt to hit this target. There is a slight delay between when the target is determined and when it is achieved (maybe 1/4th of second or so).

 

But while you're here... my only guess as to why there are separate tables for pedal-to-torque and torque-to-throttle is that the cruise control signal gets routed to the second table, and not the first. Does that match your understanding of these two tables? Are there (other?) values that go through one table but not the other?

 

Thanks!

The requested torque appears to be in N-m. That is why an STi has 400 N-m max (295 lb-ft). Of course, the ECU has no mechanical means of measuring torque. I think this is just for the benefit of the engineers. But, there is a lot that is not known about DBW. It is very hard to follow with all the redundancies and failure logic. Generally, you should keep the requested torque in the same factory range (0-320 LGT) to avoid issues with unknown logic. Raising 320 N-m to the STi's 400 N-m in the WOT column as tuners used to do, does nothing. This is obvious when you look at the LGT's throttle plate position table.