Hey All,

My first post here...

2002 X-Type Sport 3.0 Manual. I have owned the car since new and it's still going strong with over 219K miles. I am a spirited driver and I have never babied my X-Type. I frequently accelerate hard off the line and every summer I am disappointed with the lack of response of the throttle.

Over all of these years, I have noticed that when the outside air temperature is hot, 90F+, the throttle response is rather sluggish. With the X-Type, I have always noticed a slight delay all year long with throttle response, but during the summer it's extremely annoying.

I know everything is computer controlled and throttle by wire with multiple sensors. I have noticed this sluggish throttle at all stages of the vehicles life, new, old spark plugs, after complete servicing....etc. I know there are aftermarket companies with add-on modules to increase throttle response, but I have never tried them and I doubt I will. Is this something that can be programmed out of the PCM?

Has anyone else experienced this sluggish throttle when hot outside temperatures? What have you done to compensate/fix?

Thanks,

Henri

 

Welcome to the site!

I'm surprised to hear that there's such a marked difference in warmer conditions but a 'chip' or add-on widget won't do anything for you. They're the modern day electronic equivalent of snake oil.

If what you're saying is that car feels low on power- that's normal. Hot air is 'thinner' than cold air with less oxygen molecules per cubic measure to burn with the fuel. There's no way around that, unless you want to get into supercharging or turbos.

Maybe I've misunderstood?

 

Mikey is correct, another option besides a supercharger/turbo is a cold air intake.
I'm not an expert or anything, but a cold air intake would solve the problem what it does is air is sucked in through this device and is super chilled to produce cold air which provides more oxygen hence more power.

however your next question is: Will it fit?

I do not know.

~Boss

 

I have a 2002 w/ auto, and have noticed some of what you are experiencing - at least the initial acceleration "lag" of maybe 3/4 of a second.

My thoughts on it are that it is actually a design feature. When I punch the pedal to the metal it waits that 3/4 of a second as if it is asking "Are you really sure you want to do this???" , and then it goes bat-outta-hell for me.

Possibly one of the Jaguar Engineers suffered from Restless Leg Syndrome, and coded that into the computer for the occassional spastic leg jerks that can cause.

What would be nice is if the computer notices the drivers window down about half-way (as to be able to hear the kitty snarl when you punch it) that the lag is disabled. The forum here has yet to gain a member that can give us specific directions to "tweaking" the on-board Dorito (computer chip) via a laptop with an OBDII connection, a straight road and a six-pack of beer, so methinks we are S.O.L. with that.

My best suggestion is to save the thrill for the corners. Since you're not going to find it with acceleration, entering a hard corner about 40 mph faster than you should might give you the excitement you are looking for.

Having noticed that you are a new member with few posts, may I also suggest youi do some searching and reading here about how poorly the Transfer Case reacts to "hot off the line" usage. The 2002 Transfer Case is right on the top of the list for needing replacement with that kind of "performance expectation" (read: abuse).

As for the hot weather poor performance, I would blame the gasoline refineries. When they re-assemble the molecules to make/expand gasoline, the make it just want to stay liquid. They screw with every aspect of it -all in the name of profit, trust me - and the summer gas is MUCH different than the winter gas. As Mikey alluded to, "summer air" is thinner than "winter air", and that means a different gasoline composition. It is blended to not cause engine knock, but the result is it doesn't knock your socks off with performance, either.

The only place you will find the summer fuel you want for the performance you require is a small, local airport. It is HIGHLY unlikely they will let you pump AVGAS straight into your car, but for a $20 under the table plus the cost of the AVGAS they might let you fill a few 5 gallon tanks to take home and top off your tank with.

PS - DO read the forum posts about the transfer case in the 2002. At 219K miles on yours, and driving it like you describe, you will find those posts "informative". Best 'o luck!

 

Sorry to disagree, but putting a Avgas in a modern car is a serious and potentially costly mistake. 100LL has relatively high levels of TEL (lead) and will kill the catalytic converters in short order.

This fuel will also do nothing to address the OP's issue of throttle lag as it has nothing to do with octane levels. While we're on the subject- the main difference between summer and winter gas is the point at which the gas will vaporize, as expressed by Reid Vapour Pressure and mandated by your EPA to minimize air pollution. Any difference in performance between winter and summer blends is minimal, and actually favourable in the summer blends.

 

The X-Type already has air filter box snorkels in front of the radiator, so it is already getting in pretty much the coldest air possible. A cold air intake is just an intake routed so that it gets the intake air from the coldest place possible, but it doesn't the air in any way.

It's really just an aesthetic/acoustics mod (might even slightly worsen performance since a cone filter gets the air from inside the engine bay), nice thread here:
https://www.jaguarforums.com/forum/x...r-%2475-36481/

I can't think of anything to help poor performance due to the thinner summer air. Intercoolers only help turbocharged cars (perhaps supercharged as well?) because they cool the compressed air back to near-ambient levels.

 

I must seriously agree with you, Mikey, about the hazards of Avgas. I forget that I come from the "old school", where we would rod out the cat converters on the "new" cars with a long spud bar, and use a cold chisel to open the the hole in the fuel filler neck to accomodate the old leaded gas nozzle.

The added octane does indeed give things a bit of a boost, though.

The lag time with the gas pedal seems to be a built-in feature, and yes: no type of fuel is going to change that. Maybe a Holley Double-Pumper Four Barrel would help, but:

1) I doubt a manifold and linkage has been made for such a conversion, and;
2) Henniness's Transfer Case all splayed out on the road might present a hazard to other drivers.

As far as performance, I do indeed find that all the math, chemistry and science of fuel blending aside - I do find better performance in cold, high-humidity weather regardless of where purchased or what brand gasoline I fill the tank with.

I stand firmly by my comment that the X-Type gives much more thrill hitting a corner about 40 mph faster than you should, over the thrill of accelerating off the line. That bit of under-steer is more fun than the under-performance!

I think we should make book on how many more miles Henniness's Transfer Case is going to last, but I have to admit his present milage is impressive! Maybe just an Octance Booster additive and a heavier foot is all he needs, I dunno.

 

Hey All,

thanks for the responses. With my jag at over 219K and I put 600+ miles a week and it still runds strong, I can't see spending more money on it in terms of add-ons. I haven't had them all this time and I doubt any of them actually do as promised. Also, I know that summer fuel is modified by the refineries. My father was a lead chemist for one developing formulations for fuel and oil for almost 40 years before retiring. He always told me about how the fuel is different in the summer. Unfortunately, I am at the mercy of the pumps and can only fill with that they give me.

In regards to the TC exploding, I searched the forums and came across the various posts. Thanks for the heads up! So far, knock on wood, I haven't experienced any TC issues and honestly, the TC fluid has never been changed. I vaguely remember years ago when I used to go to the dealer, while under warranty, asking about the TC and the Tranny fluid and I was told "sealed for life and not needed." I thought that was a strange response, but I ran with it. I now have concern over the TC, so I'll replace the fluid for peace of mind.

For the past few years, I thought about getting something new. Not because I don't love my baby jag, but there are many times where I wish I had more cargo space and my wife can't drive stick. I take after my father in this respect that if the car isn't broken or too costly to fix, why by a new one? If the TC explodes, I think it will finally be a good reason to get a new vehicle...hopefully not too soon!

Thanks,

Henri

 

The performance difference you've noted is due to the colder, denser air- not the fuel blend. 'Winter' fuel in fact is a worse blend than 'summer' blend from a performance point of view.

Octane boosters, in addition to being mostly snake oil, would not make any difference. If an engine is not detonating, increasing the octane rating of the fuel is wasted money. Common misconception.