Just purchased a 2000 XKR and unfortunately have an issue with it. The car will barely accelerate over 2k rpm, even with your foot to the floor. It will run at 70-80mph just fine on the highway, but takes quite a while to get there. From a stop it goes normally but just hits a wall at 2k rpm. Shifts fine and goes through the gears.

Haven't looked at it in depth yet, but also don't really know where to start. Here is some more info:

-No codes at all, stored, pending, or active. Just the P1111 Jag readiness code.
-With car off/ignition on TPS goes from 4.7%-89.6% so while I could adjust the cable a bit I don't think that's causing my issue.
-I did get a Restricted Performance message blink once or twice, but only for a second and again didn't store any codes.
-Engine starts and idles great, no misses or hesitation at all even with my foot to the floor and it struggling to get over 2k rpm.

Without any codes or hesitation I'm struggling where to start with this? If anyone has any suggestions I'd greatly appreciate it. I want to say something with the throttle body since the car just doesn't respond, its as if the car has no clue I am trying to accelerate but not sure how to properly look into or diagnose if that is the case.

 

First, adjust the cable so it has a 1 to a 100 percent travel.

until that’s done you can’t really begin to properly troubleshoot anything.

Z

 

This morning I adjusted the throttle cable and getting 100% on the scan tool. Also cleaned the MAF (it was pretty dirty), and cleaned the electrical connections on the throttle body. Car runs fantastic now, very relieved! Not sure if it was the MAF or cable adjustment but very happy at this point.

It's odd, nearly every x308 XJR I've ever had needed throttle cable adjustment and have had cars with as low as 70% at full pedal travel, but they never acted like this car. Either way glad its fixed and lesson learned, do the easy stuff first and go from there. I'll take it on a longer drive later and make sure she's good, but it definitely feels like 300+hp now where as previously it felt more like a loaded down pickup truck.

 

Any owner who has never done the very simple throttle cable adjustment needs to do so immediately. That often makes a world of difference in overall performance....

 

Have you verified both fuel pumps are operational?

 

Yes, absolutely. It was on my list of things to do anyway since every XJR I've owned of this vintage had a similar issue. Funny thing is, it was not as noticeable as this car. This would absolutely refuse to rev over 2000 and would barely climb a hill. I wonder if cleaning the MAF or even reseating/cleaning the TB connections had something to do with it. I'm just relieved its fixed and there's nothing seriously wrong with it. Now on to the fun stuff; maintenance, cosmetics, tires, etc.

 

Car is all good now, but I do plan on checking that. I had a 98 XJR with a dead second pump and never noticed until I tested it. Is the procedure the same on the XK? I remember jumping pins on the 2nd pump relay, think I have a diagram somewhere.

 

wasn’t your tps, either your maf was super dirty and way underreporting airflow or still can be a major fuel pressure issue, been there done that.

it gets real bad if the car sits and the in tank rubber lines get pinholes in them.

 

Interesting. The car sat around a lot over the past 10-15 years before I took it. I thought it would be weird for the tps to cause that since I've had it read low in the past but never affect driveability like this. The MAF sensor wires were nearly black so hopefully that was the issue, but if it acts up again I'll put a fuel pressure gauge on it and check that. Have driven it two separate times since the incident so far and has been running great. Fingers crossed...

 

What wires on the MAF are you looking at ? The wire on the small bulb is for air temp reading . Deep inside the MAF you can see 2 wires that do the actual MAF determination.

Just a clarification for those as uninformed as I was ….

Z

 

The wire on the small bulb was filthy, went from black to bare metal after cleaning. I knew the other two wires were in there so I sprayed all the way down to make sure I cleaned the others as well. I did not see them before or after, but I assume they were cleaned at least somewhat by the process.

I won't have much time to mess with the car this evening, but tomorrow I plan on taking it for a decent drive to see how it acts. The 10-15 miles I did this morning were great, but that's not to say the problem won't resurface. Felt like a completely different car after the "fix", I can see its going to be a fun toy once I get everything else done that needs doing.