So, I was driving with a friend last evening, to a party in Pahrump, and since the car is "new" to me, along with the fact that my friend was admiring the smoothness, power and overall luxurious package of the new Cat, the inevitible question came up... "So, just how fast will it go?"

Well, inquiring minds prevailed over sanity and so, after a thorough check of the surroundings revealed no bogeys in sight (or any cars, for that matter) the throttle was placed firmly against lamb's wool and the big VDP dropped a couple of gears and leapt with authority from 85 mph to an indicated top-speed of 126 mph... and that's where the disappointment comes in.

Why? Why is there a governor in these things? I know, they're not sports cars but they are certainly capable of 150+ and I don't understand the rationale behind the decision to strangle the cars' top-end. Do the Super-8 and R-Type have speed-limiters too?

As a self-proclaimed speed freak, it's a bit disappointing. Having said that, so far, it's the only negative thing I can experess about this otherwise wonderful and beautiful car.

You know, if that's the only beef I can find in the XJ, I suppose it's not such a big deal but, I'd still like to flash the governor out of the computer and finally know the answer to that age-old question

Cheers!
Vance

 

They all do the same thing.
I think it's tire related, but not exactly sure.

My diesel truck stopped at 104. Got a super chip and it eliminated the governed top speed. Tried again and went 118. Fast enough. F350 btw.

 

That's so owners of earlier X308 XJR's can sucker a later model into a contest and know that they'll walk at exactly 126 mph.

 

Tyre pressure for speeds over 100 mph are much higher. On mine the car inside the fuel cap cover has them, but I don't know if it is different in the US. So your failure to reach max speed could be tyre friction. If it's not that then maybe Jaguar has limited the US cars more than the Europe spec.

 

Here is an interesting article that explains tire pressures and high speed driving.

Tire Tech Information - Air Pressure/Load Adjustment for High Speed Driving

 

My understanding....and I'm not swearing this is correct....is that Jaguar specified lower speed-rating tires on some models and lowered the speed-limiters to suit.

Rationale? The (very expensive) higher speed rating tires Jaguar specified were the source of customer complaints due to low tread life. This is not particularly unusual with "performance" tires. Apparently spending $1000+ for new tires at 12k-15k miles wasn't what people were expecting.

So.....some models (perhaps the luxury oriented VDPs?) were fitted with more conventional tires with a lower speed rating but much longer tread life. For safety/liability reasons the top speed limiter was adjusted downward.

Cheers
DD

 

Does anyone know how to disable the limiter? I know many other brands have the same issue and there are usually ways around it.

 

Yes the limiter is because of the tyres. Actually it was 121mph officially.

The only way to disable the speed limiter is by having the ECU remapped & the limiter removed from the program. This involves physically removing the ECU from the car and re-flashing it with a new program. I've been told that it cannot be done via the OBD port...

 

top speed was alledged to have been dropped with the recall 004 you need to talk to the tuners that are out there about removing it. from what I read around here thats $2k
small market and expensive cars
And yes reflashes are done through the OBD2 port, thats how we do them. problem is you have to have the car where the tuner is which in most instances lies the problem so you have to take out the ecu and send it off. But with the corrdct software and cable and tuner can send you a file to download through email and you load intot he ECU like I do with my Nissan

 

I too was disapppointed when I first learned my 04 XJ was limited to 120+ mph rather than the 155 I expected, even though I had no, ok maybe little, intention of reaching top end. BTW, my car is fitted with y-rated tires so tire capabilities isn't the issue. I have been unable to find a cost effective way to deal with the limiter. The programmer I have for my F-150 (Superchips - $400ish) does allow the limiter to be bypassed, so I was originally hopeful that a similar solution would be available for the Jag. No such luck. I did read a post some time ago that indicated the limiter could be bypassed if the shifter was left in fifth on the sport side of the J-gate. I haven't attempted it so I can't say if it's true or not.

 

Thanks, Jake. I'll give that a whirl at my next opportunity & post the results...

It is a bid odd, though. In comparison, my '06 GTO weighed 3700 lbs (nearly the same as a VDP) had IRS, 18" wheels and the tires were speed rated to Mach 3.1 or something like that... Yet, it was governed at 158 mph and hat LOTS of room left on the tach for more... Rumor has it (BBC's Top Gear) the Vauxhall Monaro, Britian's version of the GTO which, incidentally, are both versions of Australia's bare-bones but incredibly capable Holden Monaro, did a top-speed of 175mph. I don't know why Europe and that ''prison camp" down under got to stretch the legs of their machines but we unfortunate souls here in "the colonies" didn't...

Lord knows we have many roads capable of allowing it... Hell, 150 miles north of here we have a little shindig called the Silver State Classic which is a semi-annual race wherein a public highway is closed all day in order to allow entrants to run FLAT-OUT for 90 miles!!! The last race winner won with an average speed of 214 mph!

Maybe it's governed because there hasn't been an American F1 contender since Mario? I dunno...

The tires on my VDP (Michelin Pilot Sport) are rated to 149. So, I'm still pissed at the Jag brass who made this call.

Okay, enough whining. I'm off to find a Cat tuner... Wish me luck!

Cheers,
Vance

 

Not sure about that 5th Gear thing, i've seen an indicated 160mph & one of the members on the UK forum has seen 165mph, both times in Drive. So the 155mph limiter seems a little flexible. Before anyone starts both events occured in Germany on unrestricted Autobahns (he's in France, I'm in Switzerland).

According to my calculations a standard geared X350 XJR could do 193mph in 5th if you got it to 6000rpm. For sure you would need the speed limiter removed (and a hell of a long road) to acheive that...

How to remove the limiter? Well the only possibility is to have the ECU remapped, and the limiter removed in the new program. I've been in contact with a remapper in the UK, it seems the first time you re-write the Denso ECU it has to come out of the car & be re-flashed on the bench. (his words, not mine) Subsequent maps can apparently be loaded via the OBD port, at least on the 2.7L diesels, the V8 is yet to be confirmed. It's not the same as using an IDS to re-flash a factory file, so they say...

This guy in the UK quotes £199 ($315) for a remap. Which is a fraction of what the closest guy to me is asking without a dyno run, just loading the new map & aufwiedersehen! So the UK option is looking feasible to me. Pull out the ECM & get it in the post. I guess if enough people were interested then it might be worth getting an exchange program going, assuming of course that you could simply plug in a new ECU and it doesn't need the VIN in the chip...

FWIW the electronic tooling to do the re-flashing goes for around €1200 ($1475) in the UK plus the cost of buying the individual maps. So you need to do a number of cars before the investment pays off...

Oh and by-the-way, i'm from that "prison camp" down under, so you'd better watch your mouth smart-****...

The speed limit in Oz is 110km/h (68.3mph) what's the speed limit in Nevada? You'd be surprised the number of prosecutions that've used the defendants comments on internet forums as evidence in court...

 

Wooah! Easy there, big fella! I'm not trying to ruffle your feathers! While it's certainly historical fact that on 26 January, 1788, the first 736 convicts of approximately 50,000 (over the next 60 years) from England landed in Botany Bay, I'm simply making light of it. Kinda' like the way I called the USA "the colonies", you see. It's simply humor, not malice. So, cool your jets, Mr. Australian Switzerlander! It's only been 164 years since the practice of banishing British criminals to Oz stopped. Too soon for my joke?

The speed limit in Nevada is 65 to 75 mph, depending on the type of freeway.

Thanks for the advice on the ECU.

Cheers!
Vance

 

You've just posted on a public forum, which anyone can read, that you've done 126mph, on the way from Vegas to Pahrump yesterday evening, where the speed limit is no more than 75mph. That's the 160 right? Looks like a nice straight road in the middle of the desert.

You've got all your vehicles in your signature, given your first name, and where you live. And you're cracking jokes...?

 

Folks boast about flaunting speed limits here regularly. I am surprised an Internet Brands site allows it. They usually have Gestapo mods.

 

Well, I'm certainly not paranoid, if that's what you're getting at... I hope the Speed ****'s don't come and take me away or maybe some inbalanced Aussie with no sense of humor and a chip on his or her shoulder over the events of 200 years ago will come calling, packing a bag full of whoop-*** and some serious anger management issues... (Can you taste the sarcasm here?)

Really. I appreciate your concern for the possible consequences of my cavalier postings, kind sir. Allow me to put your mind at ease... You see, in the good old US of A, the Speed ****'s stay on the roadways (with lidar guns) and they don't lurk on message boards hunting for lawless speeders like myself. Such activities by police would voilate an American citizens' constitutional right to privacy and free speech. Now, in case you didn't catch that, it would be illegal. Getting clocked at 126 mph, or admitting to speeding 126 mph in a court of law would lead to a big fine and possibly a lost license, admitting to doing so on a message board on this here inter-web-thingy, not admissable in court.

On another interesting legislative note, threatening or aggressive behavior from strangers can legally be met with deadly force. So don't worry, my friend. This is America and Nevada is still the "wild west", if you will. Most of us are armed to the teeth out here and are well prepared for any and all threats.

I think your concern for my well-bieng, while very much appreciated, is unwarranted.

Thank you, nontheless.

Vance

 

Vance LEARN to use more SMILEYS or youll get taken too literally
Sarcasm is many times my FIRST language and my offbeat at times sense of humor. But then thats why they call me, MR TIBBS, er BRUTAL

 

Vespa, he may be a little touchy about the 'armed to the teeth' thing since Aussies allowed their government to take their guns from the public. Not from criminals or police, mind you. Just the commom serfs, as our government would dearly like to do.
Bobby

 

Time for a cold beer or a cup of tea and settle down guys.
Brutal's suggestion of more smileys is a good one, it is often difficult to decipher how a comment is intended when it is written a smiley often helps.
See that wasn't at all Gestapo like was it?

 

I'm smilin', I'm smilin'!!!

I think Mr. Cambo351 and I got off on the wrong foot. I'm willing to kiss and make up if he is... no tongue, of course :-)

RagJag, who's Vespa?