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Sudden Acceleration! Prius Problem with 08 LR3!
On five separate incidents with 2 different drivers my2008 LR3 HAS ACCELERATED WHEN PUSHING ON THE BREAK!!! THIS IS OBVIOUSLY A SERIOUS ISSUE AND ANYONE WHO HAS ADVICE WOULD BE KIND TO RESPOND. We have taken the car out of service and will tow it to the LR dealership (Manhattan Automobile) on Monday morning. Basically, the first time this happened in May of this year, I thought I was imaging it and that maybe I breaked and while touching the gas pedal at the same time. It happened again recently. Both of those incidents were while slowing backing up. Yesterday, I was slowing from 20 to 10 mph to take a corner and when I stepped on the break the car sped up and revved. This issue was confirmed by a second driver - that it happened to her also recently. This type of fault will kill someone. I have no confidence in this LR3 and I wonder if anyone else has any advice or had a similar issue. I know that several 2006 versions of the LR3 purported had this issue and all the dealers claim it is a software issue and the car merely needs to be "reset." I don't have confidence in that statement nor do I really believe that to be the issue. PLEASE HELP!!!!!
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As with a number of newer vehicles, the LR3 uses an electronic throttle, so a sensor converts your pressure on the gas pedal to a signal, and the engine computer uses this to control the electric throttle module. IMHO you could have all sorts of problems with this based on programming techniques, design for ignoring loose connections, actual wiring problems, grounds, etc., plus plain old corrupt software. In the old days your foot operated the throttle. Now it just moves electrons around and you are at the mercy of computers and the wunderkinds who program them.
Here's some info from the shop manual: THROTTLE BODY The electronic throttle body controls the engine torque and is located on the air intake manifold. It's main components are, an electronic throttle control valve, Accelerator Pedal Position (APP) sensor and the ECM. The APP sensor determines the driver demand to control throttle opening. This value is received by the EMS and the throttle is then opened to the correct angle by means of an integral electric motor. Sensors in the throttle body are used to determine the position of the throttle plate and the rate of change in its angle. For additional information, refer to Electronic Engine Controls (303-14B Electronic Engine Controls - 4.4L) Always be prepared to shift to "N" and take evasive action, keep insurance current and attorney on speed dial if not retainer. |
Originally Posted by Savannah Buzz
(Post 356248)
As with a number of newer vehicles, the LR3 uses an electronic throttle, so a sensor converts your pressure on the gas pedal to a signal, and the engine computer uses this to control the electric throttle module. IMHO you could have all sorts of problems with this based on programming techniques, design for ignoring loose connections, actual wiring problems, grounds, etc., plus plain old corrupt software. In the old days your foot operated the throttle. Now it just moves electrons around and you are at the mercy of computers and the wunderkinds who program them.
Here's some info from the shop manual: THROTTLE BODY The electronic throttle body controls the engine torque and is located on the air intake manifold. It's main components are, an electronic throttle control valve, Accelerator Pedal Position (APP) sensor and the ECM. The APP sensor determines the driver demand to control throttle opening. This value is received by the EMS and the throttle is then opened to the correct angle by means of an integral electric motor. Sensors in the throttle body are used to determine the position of the throttle plate and the rate of change in its angle. For additional information, refer to Electronic Engine Controls (303-14B Electronic Engine Controls - 4.4L) Always be prepared to shift to "N" and take evasive action, keep insurance current and attorney on speed dial if not retainer. |
I can understand your concern for safety and if you have a reproducible way of making this happen so much the better for troubleshooting in a safe environment. I don't recall any of the Prius incidents being proven to be faulty vehicle but I may have missed something - did they determine carpet mats slipping and hitting the throttle or some such?
All cars have electronics and just like engines and gearboxes, a lot of them come from a small number of parts manufacturers to be installed in a range of vehicles other than LR. So I don't think "smaller car manufacturer" holds much weight - LR at that time was part of Ford. Not exactly small. I've nerver heard of this before so if you get it figured out, please share.... |
Well this scares me, I hope I never have to experience this heh. I see you are in NYC, if you do get tired of the dealer shenanigans, I take my 05' LR3 to a private garage on the Upper East Side. Havent had a bad experience yet.
Sports & Classics 517 East 73rd Street New York, NY 10021 (212) 288-0173 https://maps.google.com/maps?f=q&sou...16913928061287 |
I own a 2006 LR3 V8 and have experienced unexplained acceleration 3 times.
It is pretty obvious when it happens. It is an unmistakable feeling to have to nearly stand on the brake while the truck revs to 5000 rpm. You slam it into park and it revs to 7000 rpm and bounces the rev limiter. Turning off the key is the obvious reaction but know if in motion this kills the power steering and might engage steering wheel ignition lock, a bad thing if still in motion. I have always been at a standstill, not moving when the runaway takes place. The first time it happened to me waiting in a line to drop off recycled goods, literally idling in the line with my foot lightly on the brake. The truck accelerated higher and higher as I applied increasing pressure to the brake. To those who ask stupid questions "like are you sure you were pressing the right pedal"? I am sure!, I am a mechanic. I had plenty of time to react. Enough to verify that no floor mats were on the accelerator and my foot was not crossways on the throttle either. While in park letting it rev to near red-line for 20 seconds(ouch) I can confirm that the gas pedal was free to be depressed and return freely, it was not encumbered in any way. The second occurrence I was parking in my daughter's driveway and experienced throttle runaway, she was in her car having just followed her home, She asked me why I revved the truck to red-line before shutting it off. I had the presence of mind the second time to look at the gas pedal position sensor and pedal nothing wrong there. Popped the hood inspected throttle body contacts and tapped around MAF for shorts and such. Getting back in the truck and restarting the engine it went immediately to red-line in neutral, and I shut it off. I tried reseating the connector above the gas pedal as well as the MAF sensor and on the air intake and connector throttle body. 90 seconds later the truck started and ran normally for another 6 months. The third happenstance of throttle runaway, I simply stopped at a traffic light. Sitting at idle with my foot at medium pressure on the brake. The truck starts increasing RPMs and climbing forward. I depress the brake harder and it continues to climb up to about 5000 to 5200 RPM. I turn off the ignition. I restart the truck and all is fine for my drive home. You are not alone in experiencing throttle runaway on an LR3. I just wanted to document this here for others that seem to be searching for details. It is problematic to diagnose something that happens once every 6 months to a year and works so gloriously well the rest of the time. kc0pah |
Sooo....what now, kc0pah? Are you fixing this yourself, as a mechanic? Did you take it somewhere? Are you going to sell the Rover?
I'd love to hear the resolution of this issue. It's disconcerting. |
I am replacing the gas pedal and sensor first, but that is based on similar problems I have had with other non-Rover drive by wire systems.
This issue does not throw any codes in the computer itself and is most likely either a short, open or false resistance signal to the computer from the pedal sensor. New pedal with the position sensor are cheap ($50 salvage & $250 new) compared to computer brain boxes. I hate just throwing parts without a definitive cause. That is why it took three times to get me to doo something about it. The real problem is that because it only happens once every 6 months or so I have to go 6 or 8 months or more and not experience the issue and even then how long do you go before you call it cured? That is the problem long period intermittent issues. At least mine has never runaway while in motion only when idling. kc0pah |
True....what about the Throttle Position Sensor?
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Whoa, thread from the dead!
Anyhow, 2008 LR3 HSE V8 and I, too, have experienced this backing out of the garage on several occasions. |
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