First off, if this were a new car, you would have every reason to be upset. But your dealing with previously owned (how many owners and how well did they care for it?) car that is 16 yrs old, your going to have problems, age gets us all. So, here's a thread to review... https://www.jaguarforums.com/forum/x...-p1122-150560/ ...and let us know what you find in case this needs taken further. Chin up mate.

 

Maniqz, I’ve owned a 2000 XJ8 for about 13 years. It has 82K miles. I share your frustration, but reflecting back, I don’t think I’ve ever owned a car that long before. All and all, the 8 has never been towed and has always got me home.

But, to address your symptoms, had the same and I have a similar TB as your supercharged (SC), IIRC… 1999.5 thru 2003. The throttle body (TB) has a peddle position sensor (PPS) on the left and TBS on the right. I thought for a long time the TBS was on the left… So, just a thought, are you cleaning the left connection or the right?

Cleaning the PPS connection kept me on the road for a long time until cleaning didn’t work and I replace the TB with a used unit. All is fine now. The TB’s on our cars don’t last forever. TB’s and coil packs seem to fail randomly, IMHO.

However, you could have a bad battery as well… just search the fault codes…

You said you got P1122 twice. I think you meant P1122 and P 1222, which is PPS. If cleaning the left-side connection doesn’t work, best guess is the PPS in the TB is, slowly, failing. Remedy is a TB, used or rebuilt, or new.

What I'm unsure of is whether the SC and non-SC TBS and PPS are the same. If so, you could buy a XJ8 TB and switch out the TPS and PPS... Just a thought... I'm guessing that may be your problem....

Regards…Mark

 

Fair advice above but the XJ8 has a coolant plate that the XJR does not have, you will need to swap that part from the R TB onto the 8 TB for it to fit.

 

 

The only sure-fire cure is going to be a rebuild of your throttle body. Trust me, I feel your pain. I've been dealing with an 1121 for the last year and a half now, because I haven't had a spare car to use to free up the couple weeks for a rebuild of mine. In my case, I keep a bluetooth dongle plugged in full time with the Torque Pro app running whenever I drive - when the car cuts out and triggers the codes, I jump into the Faults and clear them in the app, even underway, and it clears and restores power. In my case (and many others I've read), it seems to happen most when coasting down from speed, foot off throttle. It does other times too, but that's the most common, so I always make sure I bring the app front and center whenever I know I'll be slowing down. It's a workaround, and a pain to deal with but it at least keeps me from having to suddenly have to pull over out of traffic and find a spot to stop and restart the car.

 

What I'm still wondering is, is the Pedal Position Sensor (PPS--left side of the TB) the same for the 8 and R? The PPS is removable and replaceable. It just has tamper-proof Torx screws, but, on the 8 at least, it can be removed w/o removing the TB-- (I've done it, but it's sealed and repairing it is above my pay-grade).

The codes you're getting sounds like the PPS. As far as I know, new PPS's are not available. However, used TB's for the XJ8 are out there. If the PPS is the same for the 8 and R, cheapest fix is to get a TB for an XJ8 and change out the PPS. You might even be able to find just the PPS for sale... Alternative is to take off the TB and get it rebuilt.

Just guessing, but bet that will stop the "limp home" curse...

Regards... Mark

 

It's always seemed to be conflicting information between which are the TPPS and the TPS sensors on the bodies. I know in my case, I did replace the adjustable sensor on the side that uses those tamper screws, and it made zero difference. That's when I realized that might be the TPS -the throttle position sensor, but that the pedal position sensor might be on the other side instead. Either way I know it hates me, and nothing's worked yet lol

 

 

Someone correct me if I’m wrong, but the PPS is on the left—driver’s side, USA. The TPS on the right has the adjustable screws—heard you don’t want to mess with those because they're calibrated and hard to get back correctly. The PPS has three tamper- proof screws and only goes on one way-- it's nonadjustable. You can take it off and replace without worrying about any adjustment, although, I’ve heard you should recalibrate by switching on the ignition, slowly depressing the peddle to the floor and slowly letting it back up before starting--- I think this has to do with the TPS and is irrelevant to the PPS-- but I'm just guessing here.

Also, I’m describing “limp home mode” as the condition where the car won’t move w/o basically flooring the accelerator. My guess is--and, again, somebody correct me if I'm wrong-- the PPS is not working and to get the car to move you have to manually, with the peddle, open the TB butterfly valve with the throttle cable. The PPS basically senses the peddle position and tells the TBS to open the valve. If it can’t, the “fail safe” is to allow you to open the valve manually by pressing the peddle all the way down???

I’m by no means an expert on this whole fly-by-wire system, but here's what I've observed: the “limp home mode” problem doesn’t become permanent AT FIRST. Cleaning the connectors or restarting works for quite a while. But, based on my experiences, it will eventually become so frequent that the car will go there continually—Ask me how I know.

My point is, even if restarting or clearing codes gets you back on the road, repairing the TB—I think it's mainly the PPS-- is necessary. If cleaning the connections works, great... but, I've looked at them and they seem air and water tight. I'd clean the connection once or twice and if the problem returns, it time to replace some parts...

Maniqz, I haven't used them but ASI says they rebuilt these TB’s... A used one worked for me but I have an 8 and you have an R... My only point is, if you can get the tamper-proof torx bits and get your hands on a PPS that fits, that might be a quick, not too cheap fix.... Hope someone will chime in if the 8 and R’s PPS are the same...

Regards… Mark

 

For review... JagRepair.com - Jaguar Repair Information Resource ...and... http://jagrepair.com/images/AutoRepa..._2001_OBD2.pdf

 

Yes they are, we are talking about the AJ27 throttle body. The TB's are the same unit, but the XJ8 has a coolant line that the R doesn't have. This coolant line attaches to the back of the TB on the XJ8. The R has a blanking plate, they can be interchanged so the TB fits either.

The external sensor is the TPS - this unit can be fine tuned - the internal is the PPS and cannot be tuned.

Both sensors work on duel tracks, as they wear the signal drops - car posts a code and goes restricted. Depending on the amount of internal wear the fault gets more frequent with more miles. People on this forum have searched long and hard for replacement TPS sensors - look at the XK8/R forum for examples. (same TB).

A low miles TB or sending the TB to ASI are the options available.

 

 

Car-Part.com--Used Auto Parts Market ...or check in the Marketplace and try to find Col Sandurz thread. He was cleaning out a lot of overage from his garage.

 

I can fully recommend the ASI rebuilt units. Not as cheap as they once were, but I have had zero issues with mine since it was done, and they guarantee their work