I have a 2000 XK8 Coupe, which I love, but recently I am experiencing the car suddenly lunging ahead, running the rpms up to around 2000. This has been happening for awhile, though at first it was so subtle that I thought I was imagining it. It seemed to at first do it only when I the car was cold and I was backing out of my parking spot. As it became more overt, I made sure that my foot was not on the pedal and made sure the cruise control was off. Now, the other day I was pulling out with a bit of room and was able to take my foot off of the pedal and let it accelerate to 2000 rpm, when it finally relented. It is happening so frequently now that I am afraid to drive the car. It doesn't seem to matter if the cruise is engaged or not. The other day I was at a light and thankfully my foot was on the brake when it decided to accelerate. I read to posts and saw a discussion about taking it into the dealer to have the trans/cruise reflashed? Do I need to take it to a dealership? Or is this something my regular mechanic can take care of? Thank you...

Is the 'check-engine' light on?? Maybe there are codes stored in the engine module?

bob

Likely to be an air leak but without an OBD tool to read the data you could only guess and swap parts - gets expensive very quickly, many times the cost of the tool.

Welcome to the forum jetway,

As you have found with the coil replacement, throwing parts at a Jaguar is an expensive and rarely effective method of troubleshooting. The first step should always be having the codes read.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some information about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

TSBs might help. You need to read as many as you can. Jaguar issued info about known or suspected faults.

bob

Happens to mine sometimes. Clean the MAS and all connections to it. Also cleaning the connectors to it, and to the TBS. Should be fine then.

First thing I would try is a reset.

Two ways of doing it. Disconnect the battery leads then touch one lead to the other to discharge anything in the system. Never been brave enough to try that method myself, just does not feel right.
The other way is to disconnect the negative lead and leave for quite a while, say overnight. If you do disconnect the battery a frank tip. Put a towel etc over the boot/trunk latch so you do not accidentally lock yourself out of the boot/trunk after the battery is disconnected.

This should reset your system. Could help?

You may need your radio code and to reset your windows afterwards. Windows are easy. Sit inside car. On each window push the down button and hold it down till you hear a faint click. Then all the way up and hold it there till you hear another faint click. Jobs done!

Hi Bob, Yeah, I have been dealing with continual ck engine lights that always led to a coil misfire(s) after we put the OBD tool to it. After we replaced two coils and the MASS, I went ahead and just replaced all the plugs, and as long as we were at it, all the coils because we were concerned about toasting the computer (ECU?) Reading the OBD tool while chasing this issue, we never saw anything that indicated a problem that would lead to this unintended acceleration issue...but then again, we weren't looking for it either.

I see you referencing a TSB...Service bulletins? Is there a source where I can access them? larueb references cleaning the connectors to it, which would not indicate a service bulletin...

My first car was an English car (MGA), and you do get used to the process...I currently own a 1967 Triumph GT6 and suffered happily thru an XKE and a Healy 3000...I was hoping that Ford might have mitigated the gremlins....we will see...When I get done with this issue, I need to address the growl in the rear end...Sure is a sexy car! I love the coupe.

Thx all for the assistance.

The most complete site I've found is Gus' - Jagrepair.com
Another is - X100 Large file area

The TSB I posted is for the CAN bus fault due to the INST PK solder joint.
As stated, Gus has all that I have (I sent him all I have) plus more. They are compiled on his site for easy access.
If you read, study and understand all the TSBs Jaguar issued, you would be able to answer most questions posted here and be held in AWE as to the vast knowledge you posses.

Most people only want to know enough to repair what is broken and not much else. (until the next time) That is human nature.

bob

Without access to the car, my best guess is that you have a bad throttle body. These cars are drive by wire, there is no direct cable connection between the accelerator and the throttle plate. The throttle cable has an interpreter that signals the ECU to send a signal to the throttle motor as to pedal position. The Throttle position sensor (TPS) on the throttle body also sends data to the ECU as part of this system. The TPS is a known failure, and when it goes bad, you get the multiple messages in the instrument pack. The ECU could also be the culprit, but the TPS is the most common fault.

Thanks a lot Bob...I love to learn...beyond English cars...I love German and do most of the work myself. BTW...I am pretty able around a website but as of yet, I haven't figured out how to ad my different cars to my profile...have a shortcut? :O) Poked around quite a bit today and ran out of time. ~S

Ah...that make sense...I did install a new throttle body but the TPS sounds interesting...I bought a rebuilt throttle body, would the TPS be an additional part to purchase, or would it have come with the new throttle body?

I don't see how a bad TPS would cause the acceleration let alone not throw the car into limp or similar mode, because the PCM knows from the accel pedal what you're asking by way of air flow, then the TB is told what to do and if it reports something else then you get codes/limp mode.

Also, on the drive-by-wire cars Jaguar fit 2 sensors on the accel pedal and 2 to measure TPS and if any are weird it flags codes (and limp mode).

It's not hard to read the fuel trims!

Well...the car is going into fail safe/limp home mode...maybe there is something to ck out. I will dive into the service bulletins today...and Amazon has just let me know that my code reader is in my mailbox. Thank you for your input...

Generally, a rebuilt throttle body will get a new TPS,but shops can vary.