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.

 

If you floor it, it drops a gear and goes. Engage kickdown. Switch under the accelerator pedal.

 

Do you know if the secondary fuel pump works? I know when I test drive customers R cars and if it doesn’t have much grunt at full throttle, I jump the secondary fuel pump with the key off and listen for FP operation.

 

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.

 

Mayhem, now that you mentioned about the cable, my daughter called me one late night and said her car wouldn’t accelerate. She was just a few miles away so when I got there, the floor mat got shoved up under the gas pedal. 98’ XJR.

 

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..

 

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.

 

You need a scan tool that will do live data reading. You start by baselining where you're at, so you connect to the car, go to live data and monitor throttle position, which is shown as a %. On mine when monitoring this I floored the throttle and found it stopped at something like 74%. Remove the left and center plastic covers under the hood and if you look at the throttle body you'll see the cable that connects to the pedal position sensor. The adjustment is made here. On my car, a 2001 which has the newer style throttle body, there is a clip that holds the pedal cable stable, you need to cut the zip tie securing it, pop the clip out of the holder and then the clip can be threaded in or out in order to give or take slack in the cable. I did mine in quarter turn increments until I topped out around 98% wide open throttle with the gas pedal floored and the kickdown switch engaged. Make sure its clipped into the holder properly and re-zip tie it so it can't come loose and button it all up. I think I also did a hard reset afterwards so the car did a throttle position re-learn.

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.

 

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.

 

Cheers for the link. Mine seems to 'not bother' kicking down occasionally in hot weather, so I'll check this at some point. My guess is the cable naturally expands when hot & gets just that little bit too long to work right.

 

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.

 

[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.

 

When you floor it what does downstream lambda voltages? Does them go up to 0.8V or plums down to 0V?

 

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.

 

It's important to replace the o-rings for the screws when replacing the gasket and not overtighten the screws. It's also possible that there are hairline cracks in the plastic cover and it will still leak.

 

Is the supercharger belt missing?