Drive By Wire Response Tuning?

We have a 2008 Subaru Impreza Outback Sport 5 speed manual.  It's slow.  It's drive by wire.  Both of these things are totally OK.

What isn't OK is the way the drive by wire responds- mat the gas, and it takes a second or so to think about it before giving you what you asked for.  Lift off the gas, and it takes a couple of seconds to start engine braking.  Blip the throttle on a downshift and it just stares at you blankly for like 5 full seconds, then gives you all of the engine braking abruptly.

Do any of the popular tuners have something that can get rid of this lag?  The delay for engine braking is by far the most annoying- I get that it's tuned this way to smooth things out and make the car easy for idiots to drive, but I'd like it to do what I tell it, when I tell it to- am I out of luck or is this a parameter that I (or a tuner) can adjust to make the pedal respond more immediately to input?

I don’t have an answer but that really does not sound right. Has it been that way since new?  I have driven many different fly by wire cars and ther were never that bad. Even Subaru’s of about that age. (My brother had one). Completely stock and I never had an issue like that. 

In reply to dean1484 :

It has been that way since we bought it nearly a year ago.  I think the severity of it depends entirely on how you drive- around town or on the highway, no problems, but slinging it through a twisty backroad or sliding around in the snow makes all this stuff incredibly annoying.

Do a search for Throttle Response Enhancers.  So far, the ones I've seen for a 2008 Subaru are only listed for the WRX, but it might work on other models. 

Pedal Commander

http://xtremeracingtuning.com

That guy should be able to help you out

I've seen the pedal commander and other similar stuff- I seriously doubt it's going to speed up the response to lifting off the throttle, unless that all happens inside the pedal module itself and not the ECU.

The lag in lifting off the gas is for emissions reasons, similar to the clutch delay lines that some cars had.

The sluggishness in giving you full throttle is for fuel economy reasons.

I find the latter way more infuriating than the former, but most DBW cars that I've driven are either tuned for decent response or can be adjusted via "sport mode" or whatever.

I have driven a car pre-post pedal commander (a scion iirc) and the biggest difference was in sensitivity. Mostly good for smaller inputs for normal driving. Think of it like a short shifter more than tuning. Unless the pedal throw is rediculious, i doubt it will help in the extremes. Drive by wire IS your problem. 

Some DBW pedal assemblies have a way to adjust the dead spot at the beginning of the pedal travel. It's kinda like adjusting a TPS. Maybe your Subaru has something like that?

This is a Kia pedal assembly. I was able to adjust almost all of the horrible dead spot out of the tip in by loosening the screws and moving it. Much better.

I have the same problem on my 2007 Jetta. The lag is so heavy I have trouble working the clutch. Since the clutch pedal is direct (no lag since it's hydraulic) and the accelerator has a lag, it's very difficult to synchronize both feet. 

¯\_(ツ)_/¯ said:

We have a 2008 Subaru Impreza Outback Sport 5 speed manual.  It's slow.  It's drive by wire.  Both of these things are totally OK.

What isn't OK is the way the drive by wire responds- mat the gas, and it takes a second or so to think about it before giving you what you asked for.  Lift off the gas, and it takes a couple of seconds to start engine braking.  Blip the throttle on a downshift and it just stares at you blankly for like 5 full seconds, then gives you all of the engine braking abruptly.

That is... odd.  I have spent extensive time driving (in the loosest form of the word) an '07 Impreza 2.5i and its engine response was almost exactly like a cable throttle.  I have yet to drive a drive-by-wire Subaru that exhibited anything but stellar drivability.

Not a Subaru fanboy, but I do appreciate that their drivetrain and chassis engineers seem to place a heavy focus to the enthusiasts, even with the least of their offerings.

What you are describing sounds like the awful mess that Nissan perpetrated on the masses with the 1.8l Sentras, or GM with the 2.0l manual trans Regals.

codrus said:

The lag in lifting off the gas is for emissions reasons, similar to the clutch delay lines that some cars had.

The clutch defuser things were not for emissions but for warranty management.  You can't break the drivetrain if you can't shock it.

The Tactrix Openport 2.0 is your answer along with some free software like ECU Flash and Romraider. The definitions for your car are available online (ECU Flash definition) and at the least will let you tune exactly how your throttle plate responds to your throttle pedal when it opens. Throttle hang is slightly harder as it is defined in another table in the ECU that may or may not be defined for your car as it was discovered after a lot of these ECU definitions were originally made (but if I had to guess being an Impreza it is likely defined as well, here's an applicable thread for an 08 Legacy). I've gone through this with my 07 Legacy wagon 2.5i 5mt and am pretty happy with the results, the car responds to my inputs much better and with some of the tuning I had done (and tweaked a bit myself) the engine really picked up some power under the curve. These cars stock are very hesitant to richen the mixture even with full throttle, if you go for a drive with an OBD2 scanner plugged in watch the AFR as you do a full throttle pull, it'll hold a stoich mixture until 4000 rpm and then finally start adding more fuel. It gives good fuel economy and the engine still hits the peak numbers on the dyno put it leaves a lot to be desired.

Some more reading on Subaru DBW tables

At the very least you should download the software (ECU Flash), find a stock definition for your car or a similar one (I can send you the stock and modified ones for my for my Legacy so you can see what I have going on) and take a poke around to see what everything looks like. If all you do is play with the DBW it is very simple but you'll likely want to play with some of the other tables to unlock some performance. You can also turn nuisance trouble codes off (car will pass a plug in E-test this way) along with data logging and scanning Subaru specific codes. Ask around your rally group too, I bet someone has an openport they'll loan you.

Adam

I have a Sprint Booster in my 911 and it fixed the e-gas.  They make them for Subaru.  It has a button that allows you to select setting between off and linear (like a cable) on the fly.

Apis Mellifera said:

I have a Sprint Booster in my 911 and it fixed the e-gas.  They make them for Subaru.  It has a button that allows you to select setting between off and linear (link a cable) on the fly.

I also have one on my Genesis as well due to slow and soft throttle response to pedal movement. My car is an automatic so i dont have the same shifting issues as you guys but it brings the pedal feel to a more normal, cable-like feel

I have no answers for you, except to tell you that this alone was the reason I traded in my Scion tC after only a year. I loved the car. I loved the interior, I loved the controls, I even liked the way it looked. I really miss that sunroof. But the damn DBW was so laggy I couldn't stand it, it almost got me in trouble a few times trying to pull out into traffic.

Nugi said:

Drive by wire IS your problem. 

Well, the implementation maybe. I've driven several good throttle by wire cars and at least one terrible one. The terrible one was a Passat that had very similar behavior to what noncak (err,  ¯\_(ツ)_/¯ ) is describing with the subaru. My GS430 was throttle by wire and you really couldn't even tell, it drives just about exactly like a cable throttle equipped car.

Very interested in this thread. My DBW 2005 Legacy has been driving me bonkers for 13 years.