When I step down on the gas in my 2007 Grand Prix 110,000 miles or 2013 Cadillac XTS they both push you back in the seat and move out. My 2001 XK8 105,000 miles does not in normal or S mode. If I floor my other 2 cars I get the dang, this is fast reaction. All I get with this Jagusr is, well its smooth, but dang it's slow. It doesn't feel like there is any issue such as missing...it just feels slow on pick up like why us this good size v8 so slow. I want to feel thst instant throw back in the seat, feel the power and watch the speed rise quickly. I'm not interested in electronic S changing shift points. I want to feel power from the engine vs shift points. I've adjusted the throttle cable, I saw no change.
Did I buy the wrong vehicle to feel this? Any things i can self check without spending hundreds of dollars in a shop to figure this out? I really like this car, but this is really disappointing. Thank you!!!

 

If you have adjusted your throttle cable, you may want to clean your throttle body to ensure the butterfly is operating correctly. But keep in mind that these are GT cars, not drag racers....

 

Adjust any slack in the throttle cable as a first step. These are GT cars and not drag racers , but they are not slow. 0-60 mph should be about 6.5 secs with a top speed of 155 mph ( fastest I have done is a shade over 130 when I chickened out )

 

You don't say of the gearbox is shifting down. If not, this is why it appears slow. I think there is no kickdown switch on your model year and kickdown is triggered by throttle position. So, if not achieving 100% throttle (or near to it), kickdown will not occur. What happens if you use the J Gate to select a lower gear?

 

I know the OP says the throttle slack has been adjusted out, but has the TPS been used to verify that 100% is being achieved when the accelerator is floored ?

it might be good to check that before going down the rabbit hole .

Z

 

Hi Barry, as I opened with I adjusted the cable and it did nothing. It seems that would only help if infloored it to wide open throttle anyway, right? I dont smash it to the floor. I just want to press the gas and feel the instant push back in the seat like I can in my 2007 grand prix or Cadillac. On the 0-60 at 6.5 thank you. That shocks me and I dont think this car is even close to thst. Idk how I could check that in my area, but I'll look into it. At least it's a benchmark I didn't have.
mark

 

Don’t know about the 4.2’s, but my 4.0 L XKR starts out in 2nd gear unless the Sport Mode is engaged, in which case 1st gear is used from the standing start.

Rate of acceleration definitely suffers when the car starts out in 2nd gear.

if no difference in acceleration is detected when the Sport Mode is selected then something is definitely amiss.


Z

 

It sounds like you just got the car. I would do a complete service on the car. I would change all filters including the fuel filter. Oil change, transmission service, new plugs fuel injection cleaner in the gas. Clean the throttle body and the MAF. Check all the connections for leaks and verify the alternator voltage, check tire pressure. If performance does not improve at least you know its not a maintenance issue. When I first drove my 2000 convertible it seems slow but as I took care of the maintenance issues the car responded well and performnace improved.

 

The crap acceleration matches the crap brakes. IM HO

 

I love how my xk8 gives me a nice lil BIT of a jump but a nice long band of smooth acceleration... there is nothing jarring, sudden or extreme about it, which is just the way i like it.

Ive noticed the difference in S or non S mode and either way,,, pretty much silky smooth weather 1st or 2nd gear start, and I likes. Then, its almost like the peddle is bottomless. This was true with the 215k engine and trans and the 36k engine and trans - of course the 36k is peppy-er AND smoother - but still silky smoooth...

I aint a fast driver at all. At the same time i have a 928 and have been STARTLED by what that thing can do... different car.

The car is heavy. So much to it (mass) i dont even think THE CAR would like hard core off the line take offs... Its not that kinda car. Got a big ol rubber shock absorber (basically) in the drive shaft.

I was driving with my lady the other day, last beach outing of the year sadly/maybe, and she commented on the feel of the car. Mind you, shes from Detroit and is/was a trained machinist with a physics mind. Commented on how much the XK is NOT the 928,,, i took the hint...lol

Anyways... It is what it is.

 

I thought that too but I noticed that the peddle has a long throw and pushing it further gave better acceleration. Most of my others are a little abrupt off idle mistaken for more power or responsiveness. As mentioned the Jag is not that kinda car. A little sporty but mostly luxury. It's still a sweet ride. Enjoy for what it is. TM

 

I had it slightly tighter and the idol rpm race, so I had to back off.

 

To me the feel is all sport, little luxury, that aside my gas pedal past a certain point is hard requiring crazy effort to push. My Cadillac XTS is luxury but easy petal push and it lays me back in the seat. I saw a 6.5 second time for my XK8 was standard. I dont have any way locally to test that, but I'm confident it's not close. Something I've also noticed, when completely letting off gas in idol, the RPMs drop almost to stall tgen recovers. Wondering if this is related to the slow acceleration?

 

Thabk you. Yes I just git it. The items you suggest are a large bill, but I completely understand most items and their relevance. Let me ask this, I use to in the 60s and 70s change points, plugs...but since all tge computers adjust spark for wear I've not even thought about plugs. Thus car has 105,000 miles and meticulously maintained. I'll be checking filter and expect it to look new. I've gotten some scoop on how to get to the plugs and the extra long extension needed for the 17mm plug socket. If I find old worn plugs, what kind would be best for replacement?
mark

 

I put these in my ‘02 XKR:

NGK laser iridium IFR5N-10

NGK Laser Iridium 7866 IFR5N-10 Laser Iridium Spark Plug, 4 Pack https://www.amazon.com/dp/B00BS3ZWF6/ref=cm_sw_r_cp_api_glt_fabc_3C1HSK48GVJRVPSWZ7JS

Z

 

Many responses are from second generation owners. 2003-2006 (or supercharged) are completely different cars. Torque kicks in lower.
Six speed is smooth but seems more precise even in auto mode. I've test driven an 04 and 06. Both felt much faster than my 00 with very little effort on my part.
I can make my first gen "feel fast" but have push the gas pedal harder, hit higher rev's and manual shift to make it happen. Reducing throttle cable slack def helps.

 

Yes you did.
It sounds as if you are expecting the type of torque you get from a usa v8, this isn't that.
If you want the xk8 to accelarate hard you will need to use the shifter and nail the throttle..it will surprise you.
The xkr would have been a better match for your expectations.
Sorry to rain on the parade.
wj

 

A trick of American auto manufacturers since the mid 60’s Mustangs was to engineer the seat back spring material so that it collapsed rapidly under modest acceleration, giving the impression of immense torque and acceleration.


The rpm dropping off, and the engine nearly dying circumstances, sound like a very dirty throttle body.

Z

 

Seriously on the seat material? If you engineer the pedal so 2" of travel (w/ minimal resistance) gets full throttle, it will also seem fast Undrivable of course.

 

of course serious, retired Ford engineers have confirmed the practice numerous times at vintage car functions . The early Mustang seat back also had some “give” built into the hinge which pitched the entire seat back backward a few degrees when the car was accelerated moderately. That, combined with the seat back spring engineering made the car a lot “faster “.

Automotive Engineers know all the tricks to dupe the gullible public into thinking their car is faster than it really is.


Z