Actually, the true reason for the foot on the brake to start is for separation of the numerous 'power modes' the electronics use. For instance 'crank' is power mode 9, 'ignition on' is power mode 6. The only way to separate 'crank' from 'ignition on' with one button, is to require the foot on the brake so it knows the driver wants to start the engine, not just turn on the ignition.

The assumed safety aspect is just a bonus.

Cheers,

 

It's not over yet....

Let the real experts weigh in....

Toyota's Sudden Acceleration Problem May Have Been Triggered By Tin Whiskers

 

That tin whisker thing is a fact for sure, it does happen. But that idea took on a near Y2K [year 2000 computer scare] quality several years ago. Planes were gonna crash, the Shuttle was gonna crash, bank computers were gonna crash, cars were gonna go crazy. Turns out the vulnerability is pretty restricted to extremely low power [current], highly sensitive circuits. I remember reading about the Toyota determination last summer, NASA tech guys discounted the tin whisker thing as contributing, I'm pretty sure.

My 2nd thought........the Huffington Post would like nothing more than to destroy the fossil fuel auto industry. Chevy Volt, anyone?? My two cents.....

Cheers,

 

The Huffington Post is hardly a model of balanced journalism.

Furthermore, this interesting quote from the article in question:

So, if you lift your foot off the gas it stops accelerating ... how surprising. And if you press the accelerator even harder, it accelerates harder ... even more stunning news.

Her original complaint was that it took more gas to get the car going because it hesitated when accelerating from a standstill. That points to an engine problem, perhaps something like a vacuum leak. Then, you have someone who is deficient in driving skills compensating by pressing harder on the gas pedal and not knowing to lift off.

That is a lack of driving skill, not unintended sudden acceleration. The car wasn't out of control, she was.

Nominated for a Darwin Award.

 

I have owned an XJ with no problems, wonderful to drive and to me, one of the best looking sedans on the road. I was looking at getting another, but after doing some research, I won't. I think based on what I have read, that sudden acceleration is real and the Jaguar people need to quite sweeping this under the rug and do something about it, figure it out, and save these otherwise great cars. I have read posts on this forum about "fat foot". I agree that it can and does happen, but I encourage you to read the link provided and then tell me that all these incidents and stories (48 in all) are the result of "fat foot".

Jaguar XJ-Series: Sudden Acceleration - Car Forums - Edmunds

 

My wife's XK has just been fixed for high reving with not feet on the accelelotor, it was a software issue and needed reprogramming. It has been fine ever since. Apparently the car did not know where the throttle position was so dicided by itself.

 

I had that happen a number of years ago in an American car. The thottle linkage would go wide open as soon as you start to press the thottle pedal. What is was. was a brocken motor mount. The linkage was on the side of the broken mount and the torque from the engine caused the motor to rise higher than would normally happen. This result in the linkage being pulled to the full extent. It was a wild ride until I figured it out.

 

My car self accelerates and almost killed me today!!! Bought it used from British Motors....... Called them today and they said you pay to diagnose it and tow it. Hmmmmmm? Anyone in the same boat?

 

If you just bought it, the dealer should show some consideration by towing it and then diagnosing the problem..

The internet is a big space and bad press for a dealer will only cost the dealer money in the long run

I learned a long time ago that: You can get more with a kind word and a "gun" than with a kind word. The dealer would be wise to realize that

 

Please add detail like how much, when, ...?

Commonish cause on many cars is mat or the like affecting the pedal.

Another is an air leak, which revs the engine a little. Check fuel trims.

The jags were designed in a way that avoids the faults like Toyotas etc.

 

Also -- it's important to note that Toyota was indemnified for those 'sudden acceleration' cases. There were no actual documented cases of malfunction, but Toyota did alter their ECUs to automatically cut throttle if the brake was on -- something that other MFGs like Nissan have been doing for years (my 03 350Z auto cuts throttle if you stomp the brake).

The XKRs are all throttle by wire (the 5.0L are, and I believe the 4.2L are too) so, it's unlikely that a physical linkage due to something like a broken motor mount would be suspect. Not to say that the engine didn't surge, but there are a fair amount of safety nets to prevent that.

 

Who knew there were so many cases with Jaguars. Given how very few Jags there are compared to, say, Toyotas, this is pretty alarming!

 

So how does one heel/toe blip the throttle in those cars? Or is this only a feature in automatic trans vehicles?


Rich

 

Well, it might be if there were any credible ones. Are there? If so, which ones on which models & years? Are any of them the newer drive-by-wire ones? I think not but surprise me

 

You can heel/toe just fine, but you can't hot brake -- which really isn't something you do at HPDEs or the track, but you DO do in AutoX. <shrugs> There were a number of complaints about it on the Z Forums when it was initially discovered way back when, as it was an unusual feature at the time, I think, but hot braking was really only done to keep the motor at a boil and as the Z had adequate torque anyway, it was kind of a moot point.

 

One thing to think about is that it may make a big difference in RWD versus FWD vehicles for these "sudden acceleration cases". If you have a high-power RWD car, such as a Jag, it could be much more dangerous. The rear brakes on any car are much less powerful than the front brakes. I could easily see a 400 horsepower Jag engine being able to easily overcome the rear brakes. Even if the engine did not overcome the front brakes, it could definitely create a "burnout" situation and would make the car incredibly hard to control under braking.

Compare that to a Toyota Camry, which is front wheel drive. If you stomp on the brakes, you are fully negating the engine's force since it is front wheel drive and the front brakes are robust. It would not create any balance or controllability issues...

 

One thing I've always wondered in these situations: why not just switch it off? With no spark, the car might 'diesel' along a bit (compression ignition) if you're at speed, but surely it's going to grind to a halt. Obviously, not quite so straightforward if it's actually a diesel, but unless the fuel pump is mechanical, it's going to starve. From the 5.0 manual:

Am I missing something?

 

The only flaw in that, Alan, is that on the rear drive Jag you mentioned, the front wheels are still on the ground in front of those rear wheels, with their brakes still fully locked. Even IF the engine over-drives the rear brakes, they are still a formidable force in keeping the car stopped.
I will tell you this, from personal experience I know that no Jaguar since the Series III will over-drive its brakes. I have tried that with every model since then personally, and not a one will move with the throttle floored, SO LONG AS THE BRAKES [INCLUDING POWER ASSIST SYSTEM] ARE IN PROPER WORKING ORDER. I spent ten years with GM [Oldsmobile] before that, and not a one of them would either.

I don't think you are missing anything, I think it's just a case where you have to consider how the mind works. When something like this happens, and it has happened to me, instinct takes over, not clear thought. My work boots straddled the pedals in an XJS and pressed both at the same time. Car took off unexpectedly, I swore it was the car that accelerated. Instinct made me slam my left foot on the brake to stop the car. Someone asked me why I didn't just shut the key off. In the moment, that isn't what came to mind, stomping the brake did.

When panic sets in, it's hard to say what the mind is gonna tell you to do.

Cheers,

 

Oh, I agree, if it's a brief sudden thing, your brain doesn't really comprehend what's occurring. I've done the reverse - stomped on the brake thinking it was the clutch.

It's more these situations where people are already in motion and then can't slow down. I just can't believe that there was nothing they could do. Turn it off, put it in neutral; if all else fails, scrub speed off along the armco.

 

Twice my 2007 S-type, 4.2 non turbo, went into full throttle while I was almost stopped. Once while backing out of a parking space, the second time at a stop light. I immediately turned off the car and restarted it. It ran fine then. Any clue why this happened. I would like to add, the second time when I stopped the car at my destination, I put my gauge on the car. No error codes.