Floor the gas pedal at 70mph on freeway, no acceleration
#1
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My XJR has 3 passengers(about 525lb extra weight) . I am going 70mph on the freeway, on Normal(not Sport) mode, on D, at regular cruising RPM, on CATS. I try to turn left to the inner lane and floor the gas pedal (still under 3500 rpm I think) but I'm not feeling any speed acceleration or seeing my speedometer moving up fast to 80mph. Only after I let off the gas pedal and step on it again does it moves up. Is it just the extra passenger weight that I'm imagining or is the transmission not ready to shift yet? I don't have a Check-Engine-Light, and have replaced with new spark plugs and ignition coils. And should I leave my car in Sports Mode all the time?. I drive it on weekends and only have the car for 9 months and driven it 5k miles so far. Car has 77k miles currently. Maybe I need more time experimenting with it? Today, if I leave it on Sports Mode, it might seem like I am getting better acceleration reaction from the car on the freeway but I could be imagining things versus Non-Sports? I at least expect it to be responsive like a non-M BMW.
Last edited by Thinkpad240; 01-28-2024 at 01:41 AM.
#2
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Don B (01-28-2024)
#4
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My 01 XJR refused to do much kicking down in non-sport mode when I first got it. Found out after while that my pedal position cable had been stretched significantly and I was barely getting 70% or so throttle with my foot on the floor and kickdown switch depressed. I readjusted the throttle up to about 98% WOT and the car really woke up.
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Don B (01-31-2024)
#5
#6
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How do I readjust the throttle on my XJR, just wondering not that may do it? When I first got the car, it won't go past 3k RPM cruising around 75MPH until I turn on Sports Mode so I can start making some passes. I also think I need to take a few weekends for 8 hours at least daily on the backroads, driving the car fully in manual J gate mode or with Sports mode button on. Should be fun? With my driving, I'm at half tank in one day or something like 15mpg worst or 19mpg on normal driving..
My 01 XJR refused to do much kicking down in non-sport mode when I first got it. Found out after while that my pedal position cable had been stretched significantly and I was barely getting 70% or so throttle with my foot on the floor and kickdown switch depressed. I readjusted the throttle up to about 98% WOT and the car really woke up.
#7
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In comfort mode, gearbox will only downshit one gear. It will never shift to engine full torque area. At 60kmh gearbox is in 5 gear. When floored the pedal, box will downshift to fourth gear and use engine torgue to speed up. In sport mode box will go down to second gear and engine up to 4k rpm. I use the sport fuction only when I know I have to use the full blast. In this way sport mode is always in hectic state and confort learns my soft driving style.
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#8
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How do I readjust the throttle on my XJR, just wondering not that may do it? When I first got the car, it won't go past 3k RPM cruising around 75MPH until I turn on Sports Mode so I can start making some passes. I also think I need to take a few weekends for 8 hours at least daily on the backroads, driving the car fully in manual J gate mode or with Sports mode button on. Should be fun? With my driving, I'm at half tank in one day or something like 15mpg worst or 19mpg on normal driving..
All of this is with the engine not running, just key on so your scanner can connect to the computer.
I'm not sure of the differences with the older AJ26 throttle body with the vacuum canister. I suspect its similar, but haven't touched one myself.
#9
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There is a good write-up with photos here on the throttle cable adjustment. Definitely need the scan tool, but it's about a five minute job, provided you don't have to run to the store to buy an OEM zip tie
The photos matched how it looked precisely on my '99. FWIW I never have sport mode off, in my car. The kickdown is heroic.
https://www.jaguarforums.com/forum/x...-03-xj8-72814/
**EDIT** Maybe not "precisely," as the engine in the thread doesn't have a supercharger. The throttle cable, etc., was all the same, though.
![Big Grin](https://www.jaguarforums.com/forum/images/smilies/biggrin.gif)
https://www.jaguarforums.com/forum/x...-03-xj8-72814/
**EDIT** Maybe not "precisely," as the engine in the thread doesn't have a supercharger. The throttle cable, etc., was all the same, though.
Last edited by SOCONN13; 01-31-2024 at 11:23 AM.
#10
#11
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So today, I drove on the freeway normally, on Auto, for about 1 hour. Afterwards, a coffee break for 1 hour. Then, I took the car on the nearby highway using the J gate (in Sports Mode\ Non-Sport Mode) for about 15 minutes. I was driving in the open hills, not steep and manually shift between 3rd or 4th gear at about 3.5 k to 5.5k rpm for about 10 . It was never red lined. After I parked and turn the engine off, I can see lots of grey gas fume coming out of the engine compartment area. Upon further inspection, it seems to vape from the bottom or mid section of the engine. I let the car cool for 5 minutes until the vapor were gone and then drove with the J gate for another 15 minutes but it never vape again after I turned off the engine . The oil temp gauge was in the middle reading(normal) during the entire trip and I always checked\refill my motor oil and coolant level each month. Is this vapor normal or could it be related to needing to replace the oil pan (and valve cover gasket has some seeping), as my mechanic told me months ago that there is some leak under the driver's side? Why did it vape only once? This is the first time I got my engine spinning near redline though only a few instances. From looking from the top , I can see no oil leaks or smear, from the engine, as before. And Yes, I did get the power surge from the downshift using the J gate from 4th to 3rd gear. It was a much smoother experience that I expected . And I do have live view on my ODBC reader but I don't think I need to adjust the throttle.
Last edited by Thinkpad240; 02-04-2024 at 02:06 AM.
#12
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[QUOTE=Thinkpad240;2718568 Is this vapor normal or could it be related to needing to replace the oil pan (and valve cover gasket has some seeping), as my mechanic told me months ago that there is some leak under the driver's side? Why did it vape only once? .[/QUOTE]
So the cam cover seals weep oil that flows directly down onto the exhaust manifolds, depending on how large or small the leak is directly related to how smoky it is. It only gets worse and any leak is a bad leak as these can cause fires in extreme failures.
So the cam cover seals weep oil that flows directly down onto the exhaust manifolds, depending on how large or small the leak is directly related to how smoky it is. It only gets worse and any leak is a bad leak as these can cause fires in extreme failures.
#14
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Let me look further into this. I'm thinking I need to get the valve cover gasket replaced first and have the voltage looked at about the same time. I've been driving after smelling that odorous exhaust fume from tailpipes coming on briefly after starting the car, for over 6 months now. It just does not smell like a normal car would.
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