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Old 09-24-2014, 10:33 PM   #1
cloudballoon
 
Drives: 2007 Yaris Sedan
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Location: Ontario, Canada
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Gas pedal stuck? 2nd time happening now

My wife has a 2007 Yaris sedan, automatic. 3~4 months ago, I was driving the car and I wanted to pass a slow moving car in front of me on the right lane (and I needed to turn left on the next light anyway), so I got into the left lane and sped up a bit (to ~40mph, from ~30mph) to match the traffic flow speed, then I heard the driver behind me (he was quite far back when I came out from the right lane, I won't consider myself was cutting him off at the time) didn't like that I got in front of him started full throttling and closing in on me. I heard his full-throttling and so I accelerated quickly so he won't hit me. At this time the car when went full throttled, over 6000rpm, all by itself. It continued the high revving and I was soon gonna hit the car in front of me so I drove it to the "left-turn only" lane which is cleared of any car and shifted to neutral. It then quieted down and I can shift it back into D and drive away.

5 days ago, similar thing happened. I was at a T-section and needed to turn right onto a major fast-moving boulevard. I got a small window of opportunity to merge and I took it, but I needed to pick up speed quick to match traffic flow if I don't want the driver behind me (after I merged onto the boulevard) to need to apply break. So I was forceful on the gas pedal (but not full throttling, my car is not drifting/skidding or anything...), but the gas got stuck and revved up to over 6000rpm again. Braking didn't do anything, and again I placed it to Neutral and let it slow down and I was able turn into a residential street and the car slowed to a stand still while the engine is still high revving. I turned off the engine, waited a bit (20 seconds or so) and turned the engine back on, it immediately high-rev back to 6000+ rpm. So I turn it off again, waited like 10 minutes this time and turned it on once again. It got back to normal and I drove back home safely.

I called up my brother-in-law (who's an auto mechanic) relaying what happened, he hadn't heard it happened to a Yaris before and said maybe it's a floor-mat-stucking-the-gas-pedal problem.

I've since removed the floor mat and my wife is driving my car now instead. I'm not using the Yaris much (self-employed work at home guy) -- only twice in the last 5 days -- but want to know what are the possible issues and hope to prevent it... can anyone help me please? Thanks!
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Old 09-24-2014, 10:55 PM   #2
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The Yaris was never tagged as being one of the Toyotas with the unintended acceleration issue.

Some possible causes I could see are:

1. Internal issue with throttle pedal assembly.

2. Salt corrosion of ECM (engine computer) circuit board.

3. Rostra cruise control (if your car has this aftermarket, dealer added, cruise control system)
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Old 09-24-2014, 11:14 PM   #3
JustPassinThru
 
Drives: No more Yaris
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I'm suspicious when something like this pops up. The case of four years ago was obviously fraudulent - anyone with a smidgeon of mechanical understanding or knowledge of how to drive, would see it. The crudest of staged fakes.

Toyota for YEARS has used hooks to position the floormats; this after some mats tended to creep forward and hook the bottom of the accelerator. Yup, I have seen that, too...that's not enough to crash a car or cause a five-state runaway.

The Yaris is drive-by-wire. If the throttle is sticking, it can certainly be duplicated in thew shop - and if there's doubt, the accelerator assembly replaced. I don't know what kind of fail-safes there are to keep a short-circuit from adding fuel to the engine...but short circuits don't just come and go. They come and stay and eventually burn fuses.

If this truly is not a post done to "lay the groundwork" for the next Media Incident Runaway Yaris, then a good mechanic to check the integrity of the throttle control mechanism is in order. It's a rheostat; surely he could pull it out and bench-test it for accurate variation over the length of travel.
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Old 09-24-2014, 11:38 PM   #4
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Quote:
Originally Posted by JustPassinThru View Post
I'm suspicious when something like this pops up. The case of four years ago was obviously fraudulent - anyone with a smidgeon of mechanical understanding or knowledge of how to drive, would see it. The crudest of staged fakes.

Toyota for YEARS has used hooks to position the floormats; this after some mats tended to creep forward and hook the bottom of the accelerator. Yup, I have seen that, too...that's not enough to crash a car or cause a five-state runaway.

The Yaris is drive-by-wire. If the throttle is sticking, it can certainly be duplicated in thew shop - and if there's doubt, the accelerator assembly replaced. I don't know what kind of fail-safes there are to keep a short-circuit from adding fuel to the engine...but short circuits don't just come and go. They come and stay and eventually burn fuses.

If this truly is not a post done to "lay the groundwork" for the next Media Incident Runaway Yaris, then a good mechanic to check the integrity of the throttle control mechanism is in order. It's a rheostat; surely he could pull it out and bench-test it for accurate variation over the length of travel.
Somewhat agreed, but I have seen a couple of Yaris ECMs now that have had corrosion of the PCB from salt intrusion, that caused very odd behaviors without popping fuses or causing DTCs to be stored.

The accelerator pedal does have two separate resistive devices for registering throttle. If either varies by even a small amount, an error will be logged and the CEL will light. Electrical failure of the pedal assembly is very unlikely, but mechanical issue (i.e. sticking) is feasible.

The Rostra cruise control, which I also mentioned above, works by intercepting the signal between the pedal and the ECM and injecting its own. I have helped a few people now diagnose throttle related issues where bypassing the Rostra device resolved the issue.
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Old 09-25-2014, 02:46 PM   #5
cloudballoon
 
Drives: 2007 Yaris Sedan
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CTScott: Thank you for the tips on where to look into the problem.

JustPassinThru: Thanks for the "rheostat" tip, I'll see if my bro-in-law (small shop auto mechanic) can look into it. I'm in Canada, but I did heard about the 4 y.o. case in the USA. (Didn't stop my siblings from buying my mom a new Camry 3 yrs ago as her 60th birthday gift, LOL) I wouldn't think Canadian drivers got anything from it? I don't know, not paying attention really and I wouldn't care for class action lawsuits or what not. But wow... is it still such a sensitive issue? That's sad...

Anyway, I don't need the headache of litigation, just concerned about the safety of me & my wife... Point of my post is to see if I can fix it or whether my wife & I should look into buying another car if it can't be easily fixed (or worth fixing). It's a 2007 Yaris, and low enough mileage (about 50K miles) that we wished we can get a few years more out of it before we have to take the financial hit of getting a new car...

My concern is the 2 incidents happened months apart, and I'm not able to consistantly replicate the behaviour (I'm not crazy enough to want to anyway, not unless I can find somewhere with no other drivers around, and that means no way in the city). My brother-in-law said he can't do much in his shop and he said the regular Toyota dealers couldn't be much help either, so that's why I started searching online for help and found YarisWorld.

The floor mat (since removed after the 2nd incident) is one of those rubber mat that's popular in Canada. It's the thick, ribbed one good for holding snow in winter. It isn't compatible with the hooks, but it doesn't slip around during the drive.

What I forgot to mention in the original post was that, what's weird is that, during those 2 incidents, the car's gas pedal is stuck at a position that is close to full throttle (like I said above 6000rpm but didn't reach the 7000rpm redline zone yet), I mean it revved up to a point far beyond what I applied pressure for. Like if I want the car to go to 40mph, I would apply a certain amount of pressure to the pedal (from experience), and it'll eventually reach and stabilize around that speed. E.g. if I apply 20 degree pressure, and I can get it to 40mph, 30 degree it goes to 60mph, etc. Both incidents, the gas pedal got stuck far "deeper" than what I was applying pressure for. You know what I mean?

So if the cause is the flooring mat stucking the pedal, then the over-the-top high revving shouldn't happen because I wasn't flooring it. So a least IMO is the least likely cause.

Corrosion is possible, as we get lots of snow here in Canada and road salt is used in the winter.

No aftermarket stuff/modifications done to the car...
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Old 09-25-2014, 03:07 PM   #6
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Quote:
Originally Posted by cloudballoon View Post

No aftermarket stuff/modifications done to the car...

Does it have cruise control?
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Old 09-25-2014, 09:59 PM   #7
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No cruise control
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