My car is surging ahead when I am at a stop
 

My 2011 XF has been surging ahead when I have been at a dead stop. At first I thought perhaps my foot slipped off the brake, but I was certain it hadn't. It has happened 4 times in the past couple of months always at a stop. The last serious one was we were stopped at a drive thru window and the car was stopped, foot on brake and all of a sudden it reved down, and jumped ahead past the window. We had to put the car in N to get it to get back into D.

has anyone experienced this before?

Do an "Engine surging" search and you will see that you are not alone.

wow get that thing to the dealership! I have not had that experience in the Jag but our Toyota would sometimes bump up the idle at long lights and push against the brake pedal. It was always when the climate control was on and cooling the car. I attributed it to the AC engaging and the motor raising RPMs to compensate for the increased load? It never moved the car forward but it was hard enough that a few times I looked in the rear view mirror to see who had rear ended me.

this happens a lot. its a common issue

carzaddict, thanks for the comment. I had the car to the dealership for service, they told me there was nothing wrong with it, so we actually reported it to Jaguar Canada who again said there was no issue. Until we heard from the higher ups... So the car is back into the dealership.... hopefully they will find something. I don't want to run over someone.

You mentioned it was a common issue and all I could find was trouble with 2009's online.... any ideas where I would find more?
thank you

It could be the "adaptive transmission". Mine (2009) wasn't quite that bad but did something similar (felt like someone hit me from behind). They reset the adaptive transmission and good as new. Good luck!

Aaron

Who are the "higher ups" you are referring to? aguar Canada? How was this communicated to you?

My husband called Jag Canada, which in New Jersey... go figure. The first person he spoke to was not too interested, and after my husband mentioned the recalls and issues with Toyota she did escalate it up the chain to another department that called right back and contacted the dealership.... not sure what the role or who she was, but the car has been at the dealership for two days and they can't find anything. Ironically when I took it in the first time the service guy said well we have had a couple of other complaints like that but put it down to driver error.

normal within reason with the ZF. I get a little lurch sometimes.

https://www.jaguarforums.com/forum/x...topping-75417/

I often get a lurch forward when I put the car in park and let off the brake. I guess the solution is to put the parking brake on before taking foot off brake pedal or make sure there's enough room in front to accommodate the lurch forward. This is not related to a engine surge as engine is idling normally but is also somewhat annoying and can be dangerous. Of course dealer found no fault and recommended the parking brake solution. :icon_bump1:

Just an update, car is still at Jag. They have downloaded all of the computer info and have sent it off to Jaguar headoffice to review. Nice to see that they are taking this seriously. They will then send the data to the UK. So I suggest that anyone else that is having this problem to report it ASAP.

Sorry, but this defect simply isn't possible. It is unclear what is meant by "revved down" but, assuming what is actually meant is "revved up" then unless the electronic throttle has developed a mind of its own (itself impossible because the electronics are redundantly implemented) this engine surge is simply impossible.

Many people driving automatics simply do not put their foot on the correct pedal. This has been proven time and again when these unintended acceleration incidents are correctly investigated. It is a bizarre but all too human failure of perception. No amount of evidence or argument wil persuade the person who has deluded themselves into blaming their car.

You MUST become a more aware driver or you WILL have an accident.

As for the "lurch" when Park is engaged, all automatics do this as it takes a small rotation of the output shaft to engage the Park pawl. This "feature" is required for all automatics in order to duplicate the braking effect of being "in gear" available in all manually selected transmissions the torque converter can always slip so the output shaft is locked to the drive wheels instead. Technically, it is incorrect driving technique to park a car using only the Park pawl. One should ALWAYS engage the parking brake as well before leaving the car. I concede that I do not except when leaving the car parked on a slope.

When I had my '04 XJ8, the electronic parking brake automatically engaged when it was put into park and the engine was shut off. Is this the case with the XF? I don't see the park brake light come on in the XF.

No, the EPB must be applied by the driver. It releases automatically when the accelerator is depressed and the transmission is in gear.

Thank you for your comments......You know not of what you speak! I do know the difference between the gas and brake and do not drive with both feet. This has not only happened to me while driving but also my husband. It is a matter of time before my car jumps across an intersection or crosswalk and hits someone.

Well, OK, good luck with your driving until Jaguar can fix this. Post their diagnosis when you receive it, please. Obviously, this rare defect has serious potential consequences for the entire automotive industry, also the aircraft industry and any other industry using failsafe redundant drive by wire controls. Every single incident of this type previously reported has proved to be operator error. Yours will be the very first confirmed case of electronic failure.

Jagular.....I have to congratulate and admire your calm but persistent demeanor here. I have read your many previous posts and have learned a great deal and admire your knowledge. However, I would like to keep an open mind here since I too have experienced this problem. The first time it was when I had stopped the car in the garage and was in park with my foot on the brake when suddenly the engine rpm started racing (surge) and I did not know what to do when it finally decided to slow down to normal. The last time, I had just driven 500 miles from the mountains and was pulling into my driveway and started to take my foot off of the gas to brake and before I could get my foot to the brake the engine suddenly surged with the car still in gear and the car lurched forward towards the garage door.....I stomped on the brake and missed the garage door by inches. I have tried to blame this on my own failure somehow but just can not. Needless to say I am paying very close attention to this possible scenario in the future.. thanks

A good friend of mine was a driving instructor for a while when he was young. He informed me that pedal misapplication is very common and terrifying for the instructor, even with duplicate pedals. He relates many instances of learning drivers standing on the gas pedal firmly believing they are applying the brake. They even insist they are applying the brake. This type of problem is wired into our brains. We create explanations for observed events constantly. We constantly mistake correlation for cause and effect. We are even unable to properly process probability even when we are using the statistical mathematics! The attraction of gambling against stacked odds persists, just for example.

This is not to say that unintended acceleration is impossible, just that no verified instance has ever been proved to have happened.

Electronic throttles are operated by two independently controlled electric motors. The effective signals to both motors must produce the same result or the throttle will close itself. Even idle stabilization for changing engine loads is taken from the rpm input to the ECU and appropriate signals redundantly sent to the throttle motors.

Unless the throttle pedal is depressed there is no mechanism to open the throttle except an electrical fault which must occur concurrently, twice and in exactly the same way. Aircraft fly by wire controls use the same electronics, in principle. Modern fighter aircraft cannot be flown by humans without this software. They rarely crash and never because the electronics failed.

Jagular, sounds like you are very knowledgable about cars. It is fortunate or unfortunate that you have never experienced the issues I have with my car. The first time it happened I did think my foot slipped off the brake (while stopped at a light). But it didn't. The second time it happened again while I was firmly stopped with brake applied, third time we were at a drive thru window when the car lurched forward and the car geared down, my husband had to put it into N in order for it to stop reving. The 4th time it happened I was stopped at a traffic light, and ironically speaking with my Service Advisor (on blue tooth) at the very same time when it again lurched forward. Yes, my foot was firmly on the brake. There are people all over the internet and this very same forum that have the same issue with the car. If it were not a serious issue Jaguar would not be paying much attention to this. My car has been in the shop for a week now. Remember the Toyota recalls? Well it started with one complaint and accident. So your inferrance that it is driver error doesn't fly with me.

The Toyota accident was found to be due to operator error. Some similar " faults" we're found to be due to loose floor mats so those were redesigned. No actual fault with the Toyota ( or the Ford using similar throttles) was ever found. The throttle was redesigned but no engineer could say it was necessary to do so much less determine that any throttle of the earlier design actually malfunctioned.

These instances of unintended acceleration "occur" only in North America, itself noteworthy. Such reports are exceptionally rare in Canada.

The imaginary faults nearly destroyed Audi. Toyota and Ford wasted a ton of money tracing this non-existent problem.

As I say, your car may be faulty but it is extremely unlikely. If Jaguar finds and repairs a fault I would very much like to hear of it.

I do note you claim that the car geared down as it accelerated. The throttle position must change for the transmission to gear down. There is no physical way the transmission can gear down first. You may not believe it but you are stepping on the gas when you think you are stepping on the brake. There is no other possible explanation except an electronic throttle depressing itself, which is not possible from any conceivable fault. They just don't work that way, the throttle pedal itself is just a switch, it has no motors. The electronic throttle on the engine does not send any signals to the transmission, it can't do that.

I do note you attempt to strengthen your case when you mention that it happened while you were on the phone with your service advisor. You should know that there is extensive evidence that speaking or listening on a handsfree car phone is distracting to the point of being dangerous. Although it is not yet illegal to do so where phone use while driving is banned it probably should be. I also note the fault was not evident with a Jaguar expert actually in your car. I'm no gambling man but I'd bet serious money the reason Jaguar has had your car for a week is they can't duplicate the fault nor find any evidence of a fault.