05 OBS throttle positioner

[flat4fan]

Hey all, got a problem W/ my 05 OBS all of a sudden. Warantee expires in Jan 08. Payments continue on. But all of a sudden it seems like my TPS has gone haywire. Car surges while driving and acts like cruise control is on. Won't decelerate sometimes. I have to "kick it down" like the old days. Downshifting to 2nd is a real chore.

Anybody else have this happen to a similar vehicle? (New Sube...)

This is the 1st and only brand new car I bought for myself and I've pretty much babied it. I bought it in Jan 05 and only have 22K miles on it so far.

So is it going to start nickel & diming me now? Even BEFORE the payments are done?

Definitely not my 1st Sube, but I'm not happy the way it's shaping up.

(old man rant)

In my day we didn't get problems til AFTER the payments stopped.

(/ old man rant)

[GeneralDisorder]

If it's still under warantee then take it in. What *seems* like a TPS could in reality be a lot of things. Best to have it looked at and have any codes pulled.

 

GD

[porcupine73]

Also maybe ask if they have an reflashes available for your ECU. It seems the drive by wire models had updates.

[subeman90]

I had one I got rid of cause of these issues...good luck and let us know what the dealer says. I for the life of me could never drive mine smoothly and they wrote it off as me not knowing how to drive stick (only 15 other cars before this one was stick though:rolleyes: )

[flat4fan]

I have an appointment tomorrow W/ the dealer. I was just wondering if this is a common failure. Shouldn't be though. I didn't think of flash upgrades. Thanks for that, will mention it to them.

Will let you know how I make out.

[RallyKeith]

I know my '04 the STi had a drive by wire throttle, my '05 Legacy GT had one, and the '06 2.5i Impreza I just got has it as well. So I would assume that your '05 has the drive by wire throttle. That means it could be an issue with the sensor on the gas pedal, or it could also be an issue with the electronic throttle unit itself. With the way you say you can "kick it down" it makes me think it could be something with whatever senses the gas pedal position.

 

Also, The system is setup in such a way that when you lift off the gas it leave the throttle open a tiny bit for something like a second. Basically it doesn't drop to idle immediately like a "normal" car. Your car is obviously doing something it shouldn't do, but I thought I'd throw that out there as something for people to think about.

 

Keith

[flat4fan]

Yes I've always noticed that little delay, especially when shifting. It's rather annoying. Yes mine has the drivebywire also.

So I brought it in today and they said it had stored a code relating to " broken throttle return spring" (That's what the service mgr said) Knowing full well there is no return spring, this sounds bogus.. They also said there was a flash update so they did that. It didn't fix it. Car will still not decelerate, IOW no engine braking effect at all, and this is a 5 speed. This only happens after the car is warmed up. Cold, it's normal.

It feels like the cruise is on! It's a challenge to slow it down in traffic.

By "kicking it down" I mean it's just like the old days when we used to have carburetors and the choke would stick. So, no surprise, but I'll have to go back. Another few hours of missed work, and a couple of gallons of gas. I should charge THEM.

 

I fully expected this.

[RallyKeith]

they said it had stored a code relating to " broken throttle return spring" (That's what the service mgr said) Knowing full well there is no return spring, this sounds bogus..

 

I wouldn't be so sure of that. There is no external spring that you can see, but I gaurentee there is one inside of the electronic throttle unit.

 

So if there was a code for the broken return spring, what did they do to fix it? Also, have they driven the car and experienced the issue? If they haven't you should offer to take them for a drive to reproduce the issue. A car that doens't decelerate when you lift off the gas is a safetly liability and I would think if you got into an accident because of it, and you had taken the car there already to have it fixed, then they would be somehow liable. I don't know though.

[flat4fan]

I don't know how responsible they'd be, but I agree it is a safety issue. Not to mention it p*'s me o*.

So the symptoms are:

1. It runs normal when it's cold, but starts acting up after it's up to operating temperature.

2. It won't delelerate when I release the gas pedal. (Most times)

3. Will continue to rev and climb higher if I push in the clutch or ride in neutral. What I noticed is when I come to a full and complete stop, it will then drop down to "normal" except now normal is 1500 rpm. Or 5-600 or whatever. It's a little erratic. It Should be smooth as glass.

4. Here's another thing I noticed: if the car starts rolling on it's own (like I'm on a hill and release the brake) the rev's will climb again until I stop completely. Found this out when I stop for the mail after work, then roll back to pull in the driveway. Sure seems "brain" related to me.

I called them. I go back next Tuesday.

Wish me luck.

[flat4fan]

Oh yeah, what they did was:

"Checked for drivability concerns; scan computer for fault codes; code P1160 stored in mem; found update & applied to vehicle; updated & road tested; OK at this time."

So there WAS a code in there. They did the simplest thing, I guess I don't blame them.

I imagine the car had cooled down while they had it, combined with the new flash, the brain had to relearn driving patterns. It seemed better at first.

 

BUT, it came back. Something else is still wrong. We will see.

[subeman90]

mine did the exact same thing... rolling revs and all. This will be interesting

[RallyKeith]

mine did the exact same thing... rolling revs and all. This will be interesting

 

No, I got something intersting now...... I just traded in my '05 Legacy GT 5EAT on an '06 2.5i Impreza Wagon 5MT...... It's has throttle issues..... Nothing severe, and nothing you notice while driving, but at idle it will randomly rev up and slowly drop back down. This morning the car started up and was idling aroung 2500rpm!!!! I drive for two blocks without touching the gas pedal! After that it seemed normal. When I take the car out of gear around 20mph as I come to a stop sign the rpms drop to normal idle, but then as if it thought it was an automatic, at about 10mph the rpms blip up to 1200rpm and slowly come back down. This car was used with 16,000 miles on it, but there was nothing reported in the service department about an issue. I hope you get to some resolution on yours. I personally feel it must have something to do with the sensor that senses the gas pedal position.

 

Keith

[flat4fan]

No I think it's deeper than that. Like I said, if I roll backward or forward, it starts to rev up. So gas pedal doesn't have as much to do with it because it senses the car is moving and starts to rev. This seems more like the cars brain. It oversees the entire car; movement, speed, pedal position, fule mixtures, load, etc etc. It's just whacked out is all. All us DBW guys are in trouble.

Say tuned.

[GeneralDisorder]

No I think it's deeper than that. Like I said, if I roll backward or forward, it starts to rev up.

 

That's entirely normal behaviour - all Suabru fuel injection since the early 80's has done that. Thus the VSS (vehicle speed sensor) which is used by the cruise control unit as well as the fuel injection computer. The engine revs slightly when the vehicle is in motion to reduce clutch wear durring shifting and to make clutch engagement smoother. It's a drivability thing that they have found works better with inexperienced drivers.

 

It still sounds like you have an issue - maybe throttle postion sensor/actuator related, but this isn't part of it. Don't attribute this to a "problem" with the ECU as it's designed to do that and is functioning as it should. Your problem sounds mechanical rather than electronic - especially with that return spring code.

 

GD

[flat4fan]

I agree with you, except that 3-4000 rpms is not normal or slightly. I'm not an automotive tech so I won't profess to know what the actual problem is. But I will let you guys know the outcome of all this. It'll be nice to know the solution when we get it so that when my wife's 06 Legacy starts acting up I'll know what to tell them. (Different dealer)

[RallyKeith]

That's entirely normal behaviour - all Suabru fuel injection since the early 80's has done that.

 

Uh... I have a hard time believing that.

Let me list the cars I've owned that have NEVER exhibited this:

88 RX 5spd

97 Impreza 2.2 5spd

95 Legacy 5spd

2 x 91 Legacy 5spd

93 Impreza 4EAT

96 Legacy 4EAT

96 Impreza 5spd

2 x 02 WRX 5spd

04 STi 6spd

05 LGT 5EAT

 

Also, Mine will do the random revving with the car at a stop and my foot on the brakes.

 

Keith

[subeman90]

totally agree with Keith..it is not normal and I could make a grocery list of cars that didn't do that either like Keith did.

 

This is the reason I bought the baja...cable throttle FTW!

[flat4fan]

Well, they have my car. I drove up this morning and warmed her up. She was roaring like usual. I get there and ask the SM to drive it so he can see it for himself. Sure enough, she calms down and drives fairly normal. No racing or revving. Of course where we drove was completely flat and city type driving so we never even got up to highway speed.

But on the bright side I have a loaner, and he does acknowledge that at least something is wrong. He just doesn't see it to the degree I do.

I'm thinking it should have a code stored again. I hope.

[flat4fan]

Hi, I'm back. Got my car too. Seems to be fixed. They replaced the accelerator pedal assembly. The actuator must've been bad.

I was skeptical at first, but it does feel better. Normal, like it should. So far I'm happy. (Only drove it once so far, time will tell.)

I'm thinking DBW is not quite RFPT just yet. I sure wouldn't want to have to pay for this repair. A simple gas pedal? Not good. And now I have only one month of warrantee left. It took until now to surface. Who's to say it won't return after the warrantee expires, and cost me real money?

 

Hopefully we're done here.

[GeneralDisorder]

Uh... I have a hard time believing that.

 

Push in the clutch and let up on the gas sometime while coasting. The engine will not return to idle. It will stop at the rolling fast idle, which is usually somewhere around 1200 to 1500 RPM. There may be a timeout on it where it will eventually drop to idle speed... but it won't do it for a bit, and definitely not as quickly as if you were at a dead stop.

 

If all the ECU cared about was where your foot was at, then it wouldn't have a VSS input. It can and does adjust mixture, timeing, and engine speed based on vehicle speed.

 

GD

[RallyKeith]

Push in the clutch and let up on the gas sometime while coasting. The engine will not return to idle. It will stop at the rolling fast idle, which is usually somewhere around 1200 to 1500 RPM. There may be a timeout on it where it will eventually drop to idle speed... but it won't do it for a bit, and definitely not as quickly as if you were at a dead stop.

 

If all the ECU cared about was where your foot was at, then it wouldn't have a VSS input. It can and does adjust mixture, timeing, and engine speed based on vehicle speed.

 

GD

 

First off, go re-read what I said I don't believe.

Secondly, the only cars that do not return immediatley to idle are the new DBW throttle cars, and even those drop to regular idle after 1-2 seconds, regaurdless of speed.