Not doing a lot of work or kilometeres on my car, due to bad health. About 6-700 km's this year. Had an operation two days ago and as you will all understand, my first walk outside today was of course to the XJR Drove to a local car wash, and filled the tank afterwards. When going home, I switched off the tracktion control and floored it when the lights turned green. No loss of traction, only a rather ok acceleration. Is this normal, or should the XJR6 be able to break traction no matter what? Been wondering about this for some time and finally decided to ask.

-It's a sunny day with 21 degrees celcius. Completely dry roads. If there's a few drops of rain or the steering wheel is turned slightly, it breaks traction right away.
-One week ago the car was through MOT with no remarks, so polution levels seem fine. Thinking o2 sensors and catalysts here.
-The idle is almost perfect at just below 700 rpm ever since I replaced the tps last year.
-The car feels agile and there are no flat spots during acceleration.
-No hanging brakes, as all wheels are the same temperature after a drive.
-Fuel comsumption is a bit on the heavy side with 7.2 km/l (14 litres/100 km) at best, sometimes half that. But I live right in the middle of a city. 7-8 (always!) red lights within the first 1-2 kilometeres. The 7.2 quote is mostly highway.
-New Falken FK452 tires 255/45 17" with only a few hundred km's on.
-Andy's adapter installed.
-95 RON octane, as higher is hard to come by here.
-No error messages on the OBDII.

My head got heavy after the drive, of course from the operation, but hopefully this text isn't too messy. Don't know when (if?) I'll be able to do anything physically to the car, but all thoughts are very welcome.

 

Tires and road surface can make quite a difference.

I am presently running 225/60x16 tires on my XJR. No problem at all to "light the hides" at full throttle. I can leave a cloud of smoke and two black marks on the road for 40 feet.....probably more if I really wanted to.

When I was running the original 255/45x17 tires it was much harder to break traction....which of course is the whole idea of the bigger tires. Depending on conditions sometimes I couldn't do it all all but usually only 10-15 feet of wheelspin.

I wouldn't suggest too much experimenting. The limited slip on these cars won't take too much abuse.

Make sure your supercharger belt is tight. Also make sure the coolant topped off and the intercooler pump is working. Low coolant, an air pocket, or dead intercooler pump *will* make a difference in engine power.

With engine cold remove the hex-headed plug at the front of the intercooler/inlet manifold. Do you see coolant? If not, top-off using a small funnel to trickle in coolant a bit at a time while squeezing the inlet and outlet hoses to help burp the bubbles

Cheers
DD

 

My experience is that the intake air box is very restrictive and your sc will even cut out due to air starvation. Easy remedy is to replace air box with large air filter, it bolts right on with large hose clamp to the maf sensor and takes about 5 min. I think some people call it a pod filter, im not sure of the proper name. After install the car seemed 500 lbs lighter, faster acceleration and no sc cut off.

 

How does one know if the intercooler pump is fuctioning properly?

 

Take one of the hoses off the intercooler and turn the key "on". If coolant starts gushing out, the pump is working

Working *properly* is another matter. I don't know the flow rate specs to test for that

Cheers
DD

 

This could be a myriad of things my car was like that

I did al sorts of things remapped computer cold air induction every sensor and I mean every sensor new coils twice air flow meter twice custom headers and system even changed diff gears a hell of a lot of money as well in the end I just thought this is how they must go

Then last year I needed a new water pump and the lower crank seal was weeping so had the seal replaced at the same time well low and behold the crank shaft pulley /harmonic balancer needed to be destroyed to get it of that's when we found that the bolt must have come loose at some time and the key had slipped wedging itself
inside the balancer it had just been tightened by the previous owners workshop and a very well known and expensive shop as well that's the reason I bought the car its full specialist service history

A good second hand balancer and new key and bolt and holy cow its like I have picked up 100 HP

Goes fantastic now

I did learn about the car though thanks to this forum

I kept persevering otherwise I would have sold it earlier lesson look at everything

These cars are getting old now so the cost of doing all this was very expensive I could have bought another XJR6 for what I spent on this one

 

Another thought might be the throttle cable is misadjusted. There is an adjuster mid way on the cable to take up slack. When I first got my car I plugged in my OBDII reader and brought up the data stream for throttle position. Put my foot to the floor (engine off) and it only went to 64%.

After adjustment it now goes to 97%. That was the most I could get without bringing the throttle plate off idle. It certainly makes a difference!

 

Checked the throttle position. 10,6% at idle. 75% when the pedal touches the kick down switch and 85% with the kd fully depressed. Adjusted the cable, but unable to go beyond 91,4%. Not sure if I should back off a bit, so it only hits 91,4% with the kd depressed, or if it's ok to hit that mark before the button?

 

Hi guys, my XJR-6 also underpowered. when i plugged my obd scanner, TP position only at 37% on wide open throttle..removed throttle and accelarator cable slack and still 37%....idles smoothly on 12.9% Throttle opening at about 700 rpm.

Do i need to replace my TPS or have it calibrated to restore engine power?

 

My gut says "yes", replace the TPS

But just for the heck of it....


Are you sure that the throttle is mechanically opening all the way? This might not be easy to visually verify given the location of the XJR/6 throttle body....but I'd want to do so before replacing the TPS.

Even though you've removed the slack form the cables I have to wonder if the traction control unit (I think all XJR/6s were so equipped) might somehow be hindering full travel/full cable pull?

Cheers
DD

 

thanks doug, im gonna check cable operation this week,youre right, there might be something hindering its operation..will turn the throttle plate by hand and see what reading will i get on the scanner..will update you. thanks again