No doubt the title got you to click on this thread, my purely predictable male brothers...ha....ha....ha...

At least I didn't lie, as I think the attached pictures, the presence of 3 Big Cats, plus two of my wife's schizophrenic small cats justify the cathouse designation. Lothar asked for pictures of my Big Cats, so here they are.

Now, after an other day of driving the XKR, I have some questions;

At one point, I pulled away from a stop sign in 2nd gear and headed up a fairly steep hill.. Started out in Dynamic mode, S-mode, using paddle shifters. I gradually run the RPM up to 4000 and then applied full throttle. Throttle application for me is ALWAYS linear and analog, never stomping on the throttle. For me tire spin or chirp counts as a mistake.

When the car got near 6000 RPM it suddenly started violently jerking. The engine cut out and suddenly cut back, repeating it in very quick succession a number of times. I'm positive that I was not near the 6500 redline for the rev limiter to cut in. It felt rather violent, not like a controlled DSC or rev limiter would be expected.

I dropped my wife off at the house and went back out to a deserted highway to see what was going on. I was unable to replicate the symptoms but, I did not get to try it again on a steep uphill. What I did notice was that when I pulled the car to the 6500 redline under full throttle in both second and third gears and paddle-shifted for the next higher gear, there was a good, second+ long hesitation before the car when into the higher gear.

So, I tried to lower my shift-points, at which time the transmission shifted with the expected, normal quick shifts. It appears to me that the CPU or the TCU is anticipating the quick rev progress towards the redline and cuts power somewhat early. When I lowered my shifts points to 6000 and then to 6250, there was no hesitation in the upshift.

Anyone experienced any of this in a 5.0 XKR?

 

I have not experienced this yet in my (nearly identical) XKR... I would go out and try to replicate it for you, but I live in south Florida where the only hills are overpasses, and I don't think those are steep enough.

 

Nice car collection, looks like a small Jaguar used car lot, but beautiful place to park these babies. Looks nice, love the view.

 

I've been thinking about the acceleration/jerking issue.

I did experience something nearly identical years ago when I accidentally filled one of my cars with regular gas, instead of the "recommended" premium. I had 4 people in the car (heavy load) and attempted to pass an other car on an uphill stretch at nearly 4000' elevations. The car produced the same kind of jerking. Obviously the CPU must have detected "knock" and cut engine power. On my way downhill with the same 4 people, or over flat roads, it would NOT subsequently do it.

This time, full throttle, steep uphill, sounds very similar. Later no uphill, no issue. This time, of course I do have 91 CA premium in the car.

What I am wondering; Is there a 50 state STOCK tune for Jaguars or is there a 91 vs. 93 octane tune? I purchased the car from Texas where it was registered first. Is it tuned for 93 octane?

 

93 octane seems to be the recommended gas, but here in New Mexico I can only get 91 at local filling stations.

There is a thread on fuel octane. Premium Petrol....

https://www.jaguarforums.com/forum/x...essary-112317/

This might help.

 

There are two additional fuel pumps in a tank, which feeds a primary fuel pump.
If they are bad, or fuel level is low, then the fuel flow from a primary fuel pump to a high pressure fuel pump may be interrmetient. Under a heavy load, when the fuel consumption is bing enough,such a conditions may be followed with a various jerks (actually it's a missfires).
So, try to top up a fuel tank. If it doesn't help - remove a tank and check ventury pumps.
It's a first check. Also, i've had such a sympthoms when a pressure solenoid on a high pressure pump was failing. But if it is a failing solenoid, soon it will trigger a CEL.
Premium grade of fuel is a must for these cars - since it is a superchager vehicle, with a high temp. of air, coming into a cylinders, there's a risk of detonation under a heavy load or in a hot weather. Lower octane may destroy this engine in a few minutes, if you are unlucky. Older engines (like AJ-16, AJ-26, AJ-27 and AJ-34) were much stronger and they were able to use a regular gas w/o a problems, except a lack of perfomance.

 

The tank is nearly full, so that is not the issue. Fuel pump could be but, unlikely on a car with only 6000 original miles.

I can relate to what you describe as weak fuel pump jerking. When I had my XJ6L in the early 1980s it came with dual fuel pumps because one (Lucas, of course) always was failing. When it was failing the engine would "sputter" on uphill sections. This, much more forceful jerking was very different. As if the engine completely would cut out than come back at full power, then cut out.

I tried to reconstruct it at least in a dozen full throttle accelerations but, it would not act up again. Some of those attempts were at slight uphill but, not the steep uphill of the first attempt. Maybe next I will go back to that very steep hill and try to see if it happens again. My chief suspicion is the octane issue, just because I remembered having the exact same thing happen to me in an other car under nearly the same circumstances after I accidentally filled with low octane gasoline.

 

Thanks, Richard

I likely would not hesitate putting 87 octane gas in my normally aspirated modern Jaguar engines if I had to. Likely, the most you could lose would be a relatively few HP. But, forced induction is a different animal. I would NOT risk putting low octane in those cars. I still suspect that this is an octane issue.

 

I have to admit, I vomited a little when I saw the leaper on your XJ's hood. But otherwise, great collection. Thanks for sharing!

I accidentally filled up on regular in my XKR (nearly a full tank) but I never ran it up to 6000 rpms during that period.

 

I didn't have a choice, the dealer installed the leapers on all of his cars. Since, it kind of grew on me. I would say that most people think that it is factory original and actually like it.

 

I love the way your XKR's exhaust looks--sort of up-turned like on an F-Type (or E-Type for that matter)!

 

God Bless You...And I LOVE YOU!!

 

I've had that 'bunny hopping' symptom twice in the 75, once in Drive & once in Sport (auto shift in both modes). In both cases it was under hard acceleration from low speed. I put it down to DSC cutting in to prevent wheelspin, but I may have been wrong. It hasn't happened again, so I haven't had any reason to investigate further. I run on UK standard 95 RON (which appears to be equivalent to US 91) unless I'm 'bahnstorming, when I use 98 (US 94).

 

I believe it's effectively 'auto tuning', i.e. the ECM adjusts to the octane level it's given, presumably based on knock detection.

 

Same here. Great collection.

 

I have to admit, I'm not a fan of the leaper either on the newer vehicles as a few others have said, but I appreciate your point about it being preinstalled.

That being said, you have 3 gorgeous cars, you lucky devil and the scenery is beautiful too.

Thanks for sharing

 

Yes, I figured this NOT to be an entirely isolated issue. In my case I am nearly certain it was not the DSC, since I am rather skilled at preventing loss of traction. Besides, when I had the DSC cut-in on me once during the JaguarAlive autocross event, it was not jerking, it simply removed power for a period of traction recovery. Looks like to me that Jaguar set some protective engine parameters very tightly for it to come in occasionally under very heavy load-type acceleration and high RPMs only.

The risk of detonation always increases with RPM and, in my long experiences, not many people make a habit of taking their performance cars to redline to begin with. So, they likely not experiences this. I am not panicked about it either but, will keep a close eye on it in the future.

I always took my performance cars to redline, often and consistently. Never had ANY engine issues.

As a tid-bit, taken from yesterday's drive, I turned onto this wonderfully winding two lane country road in perfect condition. The only traffic on it was a pickup truck towing a small trailer. I patiently waited for one of the long straights with clear passing lines, downshifted to 3rd, got the RPMs to my favorite lunch speeds of 4000 and gradually but, firmly buried the pedal all the way to the redline, then into 4th and more.... I expected my wife to give me her somewhat negative feedback, like she did on the autobahn, but she was speechless during the onrush of acceleration.

Once I let up and let the car coast back down, she finally responded:

WOW!....JUST WOW!!!!....INCREDIBLE!!!!!! - while she had the same kind of grin on her face that you see from those pro-testers when they get their hands on some powerful machinery. But, true to her, she added;

"If you loose your licence for driving like this, the car is MINE"

Now that, my friends, IS a serious threat.

 

I love the pictures Albert.

Thanks for posting them. You've got a nice collection.

I normally don't like the leaper on the newer Jaguars, but it doesn't seem to be out of place on the XJ. It's probably the lighter color paint and all of the chrome up front.

 

When I saw the title of this thread, I thought, "finally, something I know about".

 

Nice collection, Albert. I'll guess knock response under high load due to insufficient octane. Any chance your car has an ECU flash that would push it closer to the threshold for pre-ignition? Glad to hear you're finding the opportunity to stretch its legs! And to think you didn't think you'd ever want the extra power...what were you thinking???